Effects of collision cascade density on radiation defect dynamics in 3C-SiC
Bayu Aji, L. B.; Wallace, J. B.; Kucheyev, S. O.
2017-01-01
Effects of the collision cascade density on radiation damage in SiC remain poorly understood. Here, we study damage buildup and defect interaction dynamics in 3C-SiC bombarded at 100 °C with either continuous or pulsed beams of 500 keV Ne, Ar, Kr, or Xe ions. We find that bombardment with heavier ions, which create denser collision cascades, results in a decrease in the dynamic annealing efficiency and an increase in both the amorphization cross-section constant and the time constant of dynamic annealing. The cascade density behavior of these parameters is non-linear and appears to be uncorrelated. These results demonstrate clearly (and quantitatively) an important role of the collision cascade density in dynamic radiation defect processes in 3C-SiC. PMID:28304397
Effects of collision cascade density on radiation defect dynamics in 3C-SiC
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bayu Aji, L. B.; Wallace, J. B.; Kucheyev, S. O.
Effects of the collision cascade density on radiation damage in SiC remain poorly understood. We study damage buildup and defect interaction dynamics in 3C-SiC bombarded at 100 °C with either continuous or pulsed beams of 500 keV Ne, Ar, Kr, or Xe ions. Here, we find that bombardment with heavier ions, which create denser collision cascades, results in a decrease in the dynamic annealing efficiency and an increase in both the amorphization cross-section constant and the time constant of dynamic annealing. The cascade density behavior of these parameters is non-linear and appears to be uncorrelated. Our results demonstrate clearly (andmore » quantitatively) an important role of the collision cascade density in dynamic radiation defect processes in 3C-SiC.« less
Effects of collision cascade density on radiation defect dynamics in 3C-SiC
Bayu Aji, L. B.; Wallace, J. B.; Kucheyev, S. O.
2017-03-17
Effects of the collision cascade density on radiation damage in SiC remain poorly understood. We study damage buildup and defect interaction dynamics in 3C-SiC bombarded at 100 °C with either continuous or pulsed beams of 500 keV Ne, Ar, Kr, or Xe ions. Here, we find that bombardment with heavier ions, which create denser collision cascades, results in a decrease in the dynamic annealing efficiency and an increase in both the amorphization cross-section constant and the time constant of dynamic annealing. The cascade density behavior of these parameters is non-linear and appears to be uncorrelated. Our results demonstrate clearly (andmore » quantitatively) an important role of the collision cascade density in dynamic radiation defect processes in 3C-SiC.« less
Displacement Cascade Damage Production in Metals
DOE Office of Scientific and Technical Information (OSTI.GOV)
Stoller, Roger E; Malerba, Lorenzo; Nordlund, Kai
Radiation-induced changes in microstructure and mechanical properties in structural materials are the result of a complex set of physical processes initiated by the collision between an energetic particle (neutron or ion) and an atom in the lattice. This primary damage event is called an atomic displacement cascade. The simplest description of a displacement cascade is to view it as a series of many billiard-ball-like elastic collisions among the atoms in the material. This chapter describes the formation and evolution of this primary radiation damage mechanism to provide an overview of how stable defects are formed by displacement cascades, as wellmore » as the nature and morphology of the defects themselves. The impact of the relevant variables such as cascade energy and irradiation temperature is discussed, and defect formation in different materials is compared.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Stoller, Roger E; Nordlund, Kai; Melerba, L
The processes that give rise to changes in the microstructure and the physical and mechanical properties of materials exposed to energetic particles are initiated by essentially elastic collisions between atoms in what has been called an atomic displacement cascade. The formation and evolution of this primary radiation damage mechanism are described to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the primary variables cascade energy and irradiation temperature are discussed, along with a range of secondary factors that can influence damage formation.Radiation-inducedmore » changes in microstructure and mechanical properties in structural materials are the result of a complex set of physical processes initiated by the collision between an energetic particle (neutron or ion) and an atom in the lattice. This primary damage event is called an atomic displacement cascade. The simplest description of a displacement cascade is to view it as a series of many billiard-ball-like elastic collisions among the atoms in the material. This chapter describes the formation and evolution of this primary radiation damage mechanism to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the relevant variables such as cascade energy and irradiation temperature is discussed, and defect formation in different materials is compared.« less
Radiation damage in WC studied with MD simulations
NASA Astrophysics Data System (ADS)
Träskelin, P.; Björkas, C.; Juslin, N.; Vörtler, K.; Nordlund, K.
2007-04-01
Studying radiation damage in tungsten carbide (WC) is of importance due to its applications in fusion reactors. We have used molecular dynamics to study both deuterium induced sputtering and modification of WC surfaces and collision cascades in bulk WC. For collision cascades in bulk WC we note a massive recombination and major elemental asymmetry for the damage. Studying the erosion of WC surfaces, we find that C can erode through swift chemical sputtering, while W does not sputter more easily than from pure W. The amorphization of the surface and the D-content due to the D bombardment is important for the damage production and sputtering process.
NASA Astrophysics Data System (ADS)
Lang, Lin; Tian, Zean; Xiao, Shifang; Deng, Huiqiu; Ao, Bingyun; Chen, Piheng; Hu, Wangyu
2017-02-01
Molecular dynamics simulations have been performed to investigate the structural evolution of Cu64.5Zr35.5 metallic glasses under irradiation. The largest standard cluster analysis (LSCA) method was used to quantify the microstructure within the collision cascade regions. It is found that the majority of clusters within the collision cascade regions are full and defective icosahedrons. Not only the smaller structures (common neighbor subcluster) but also primary clusters greatly changed during the collision cascades; while most of these radiation damages self-recover quickly in the following quench states. These findings indicate the Cu-Zr metallic glasses have excellent irradiation-resistance properties.
Accurate classical short-range forces for the study of collision cascades in Fe–Ni–Cr
Béland, Laurent Karim; Tamm, Artur; Mu, Sai; ...
2017-05-10
The predictive power of a classical molecular dynamics simulation is largely determined by the physical validity of its underlying empirical potential. In the case of high-energy collision cascades, it was recently shown that correctly modeling interactions at short distances is necessary to accurately predict primary damage production. An ab initio based framework is introduced for modifying an existing embedded-atom method FeNiCr potential to handle these short-range interactions. Density functional theory is used to calculate the energetics of two atoms approaching each other, embedded in the alloy, and to calculate the equation of state of the alloy as it is compressed.more » The pairwise terms and the embedding terms of the potential are modi ed in accordance with the ab initio results. Using this reparametrized potential, collision cascades are performed in Ni 50Fe 50, Ni 80Cr 20 and Ni 33Fe 33Cr 33. The simulations reveal that alloying Ni and NiCr to Fe reduces primary damage production, in agreement with some previous calculations. Alloying Ni and NiFe to Cr does not reduce primary damage production, in contradiction with previous calculations.« less
Deterministic Role of Collision Cascade Density in Radiation Defect Dynamics in Si
NASA Astrophysics Data System (ADS)
Wallace, J. B.; Aji, L. B. Bayu; Shao, L.; Kucheyev, S. O.
2018-05-01
The formation of stable radiation damage in solids often proceeds via complex dynamic annealing (DA) processes, involving point defect migration and interaction. The dependence of DA on irradiation conditions remains poorly understood even for Si. Here, we use a pulsed ion beam method to study defect interaction dynamics in Si bombarded in the temperature range from ˜-30 ° C to 210 °C with ions in a wide range of masses, from Ne to Xe, creating collision cascades with different densities. We demonstrate that the complexity of the influence of irradiation conditions on defect dynamics can be reduced to a deterministic effect of a single parameter, the average cascade density, calculated by taking into account the fractal nature of collision cascades. For each ion species, the DA rate exhibits two well-defined Arrhenius regions where different DA mechanisms dominate. These two regions intersect at a critical temperature, which depends linearly on the cascade density. The low-temperature DA regime is characterized by an activation energy of ˜0.1 eV , independent of the cascade density. The high-temperature regime, however, exhibits a change in the dominant DA process for cascade densities above ˜0.04 at.%, evidenced by an increase in the activation energy. These results clearly demonstrate a crucial role of the collision cascade density and can be used to predict radiation defect dynamics in Si.
Deterministic Role of Collision Cascade Density in Radiation Defect Dynamics in Si.
Wallace, J B; Aji, L B Bayu; Shao, L; Kucheyev, S O
2018-05-25
The formation of stable radiation damage in solids often proceeds via complex dynamic annealing (DA) processes, involving point defect migration and interaction. The dependence of DA on irradiation conditions remains poorly understood even for Si. Here, we use a pulsed ion beam method to study defect interaction dynamics in Si bombarded in the temperature range from ∼-30 °C to 210 °C with ions in a wide range of masses, from Ne to Xe, creating collision cascades with different densities. We demonstrate that the complexity of the influence of irradiation conditions on defect dynamics can be reduced to a deterministic effect of a single parameter, the average cascade density, calculated by taking into account the fractal nature of collision cascades. For each ion species, the DA rate exhibits two well-defined Arrhenius regions where different DA mechanisms dominate. These two regions intersect at a critical temperature, which depends linearly on the cascade density. The low-temperature DA regime is characterized by an activation energy of ∼0.1 eV, independent of the cascade density. The high-temperature regime, however, exhibits a change in the dominant DA process for cascade densities above ∼0.04 at.%, evidenced by an increase in the activation energy. These results clearly demonstrate a crucial role of the collision cascade density and can be used to predict radiation defect dynamics in Si.
Effects of the electron-phonon coupling activation in collision cascades
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zarkadoula, Eva; Samolyuk, German; Weber, William J.
Using the two-temperature (2T-MD) model in molecular dynamics simulations, here we investigate the condition of switching the electronic stopping term off when the electron-phonon coupling is activated in the damage production due to 50 keV Ni ion cascades in Ni and equiatomic NiFe. Additionally we investigate the effect of the electron-phonon coupling activation time in the damage production. We find that the switching condition has negligible effect in the produced damage, while the choice of the activation time of the electron-phonon coupling can affect the amount of surviving damage.
Effects of the electron-phonon coupling activation in collision cascades
Zarkadoula, Eva; Samolyuk, German; Weber, William J.
2017-04-20
Using the two-temperature (2T-MD) model in molecular dynamics simulations, here we investigate the condition of switching the electronic stopping term off when the electron-phonon coupling is activated in the damage production due to 50 keV Ni ion cascades in Ni and equiatomic NiFe. Additionally we investigate the effect of the electron-phonon coupling activation time in the damage production. We find that the switching condition has negligible effect in the produced damage, while the choice of the activation time of the electron-phonon coupling can affect the amount of surviving damage.
NASA Astrophysics Data System (ADS)
Beirau, Tobias; Nix, William D.; Pöllmann, Herbert; Ewing, Rodney C.
2018-05-01
Several different models are known to describe the structure-dependent radiation-induced damage accumulation process in materials (e.g. Gibbons Proc IEEE 60:1062-1096, 1972; Weber Nuc Instr Met Phys Res B 166-167:98-106, 2000). In the literature, two different models of damage accumulation due to α-decay events in natural ZrSiO4 (zircon) have been described. The direct impact damage accumulation model is based on amorphization occurring directly within the collision cascade. However, the double cascade-overlap damage accumulation model predicts that amorphization will only occur due to the overlap of disordered domains within the cascade. By analyzing the dose-dependent evolution of mechanical properties (i.e., Poisson's ratios, compliance constants, elastic modulus, and hardness) as a measure of the increasing amorphization, we provide support for the double cascade-overlap damage accumulation model. We found no evidence to support the direct impact damage accumulation model. Additionally, the amount of radiation damage could be related to an anisotropic-to-isotropic transition of the Poisson's ratio for stress along and perpendicular to the four-fold c-axis and of the related compliance constants of natural U- and Th-bearing zircon. The isotropification occurs in the dose range between 3.1 × and 6.3 × 1018 α-decays/g.
NASA Astrophysics Data System (ADS)
Beirau, Tobias; Nix, William D.; Pöllmann, Herbert; Ewing, Rodney C.
2017-11-01
Several different models are known to describe the structure-dependent radiation-induced damage accumulation process in materials (e.g. Gibbons Proc IEEE 60:1062-1096, 1972; Weber Nuc Instr Met Phys Res B 166-167:98-106, 2000). In the literature, two different models of damage accumulation due to α-decay events in natural ZrSiO4 (zircon) have been described. The direct impact damage accumulation model is based on amorphization occurring directly within the collision cascade. However, the double cascade-overlap damage accumulation model predicts that amorphization will only occur due to the overlap of disordered domains within the cascade. By analyzing the dose-dependent evolution of mechanical properties (i.e., Poisson's ratios, compliance constants, elastic modulus, and hardness) as a measure of the increasing amorphization, we provide support for the double cascade-overlap damage accumulation model. We found no evidence to support the direct impact damage accumulation model. Additionally, the amount of radiation damage could be related to an anisotropic-to-isotropic transition of the Poisson's ratio for stress along and perpendicular to the four-fold c-axis and of the related compliance constants of natural U- and Th-bearing zircon. The isotropification occurs in the dose range between 3.1 × and 6.3 × 1018 α-decays/g.
NASA Astrophysics Data System (ADS)
Delaye, J. M.; Ghaleb, D.
1998-02-01
We have performed some molecular dynamics calculations of displacement cascades in a simplified nuclear glass (SiO 2 + B 2O 3 + Na 2O + Al 2O 3 + ZrO 2). We have observed that the damaged volume at the end of the collision sequence can be divided into a so called highly damaged volume and lightly damaged volume. The aim of this paper is to propose an explanation of this phenomenon by considering that some regions are easy to cross by the projectile and others are difficult to cross by the projectile. Regions which are easy to cross correspond to those containing Na atoms with a low level of polymerisation, and regions which are difficult to cross are areas no containing Na atoms with a high level of polymerisation.
Multi-scale Modeling of Radiation Damage: Large Scale Data Analysis
NASA Astrophysics Data System (ADS)
Warrier, M.; Bhardwaj, U.; Bukkuru, S.
2016-10-01
Modification of materials in nuclear reactors due to neutron irradiation is a multiscale problem. These neutrons pass through materials creating several energetic primary knock-on atoms (PKA) which cause localized collision cascades creating damage tracks, defects (interstitials and vacancies) and defect clusters depending on the energy of the PKA. These defects diffuse and recombine throughout the whole duration of operation of the reactor, thereby changing the micro-structure of the material and its properties. It is therefore desirable to develop predictive computational tools to simulate the micro-structural changes of irradiated materials. In this paper we describe how statistical averages of the collision cascades from thousands of MD simulations are used to provide inputs to Kinetic Monte Carlo (KMC) simulations which can handle larger sizes, more defects and longer time durations. Use of unsupervised learning and graph optimization in handling and analyzing large scale MD data will be highlighted.
Atomic scale modeling of defect production and microstructure evolution in irradiated metals
DOE Office of Scientific and Technical Information (OSTI.GOV)
Diaz de la Rubia, T.; Soneda, N.; Shimomura, Y.
1997-04-01
Irradiation effects in materials depend in a complex way on the form of the as-produced primary damage state and its spatial and temporal evolution. Thus, while collision cascades produce defects on a time scale of tens of picosecond, diffusion occurs over much longer time scales, of the order of seconds, and microstructure evolution over even longer time scales. In this report the authors present work aimed at describing damage production and evolution in metals across all the relevant time and length scales. They discuss results of molecular dynamics simulations of displacement cascades in Fe and V. They show that interstitialmore » clusters are produced in cascades above 5 keV, but not vacancy clusters. Next, they discuss the development of a kinetic Monte Carlo model that enables calculations of damage evolution over much longer time scales (1000`s of s) than the picosecond lifetime of the cascade. They demonstrate the applicability of the method by presenting predictions on the fraction of freely migrating defects in {alpha}Fe during irradiation at 600 K.« less
Stochastic annealing simulations of defect interactions among subcascades
DOE Office of Scientific and Technical Information (OSTI.GOV)
Heinisch, H.L.; Singh, B.N.
1997-04-01
The effects of the subcascade structure of high energy cascades on the temperature dependencies of annihilation, clustering and free defect production are investigated. The subcascade structure is simulated by closely spaced groups of lower energy MD cascades. The simulation results illustrate the strong influence of the defect configuration existing in the primary damage state on subsequent intracascade evolution. Other significant factors affecting the evolution of the defect distribution are the large differences in mobility and stability of vacancy and interstitial defects and the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. Annealing simulations are also performedmore » on high-energy, subcascade-producing cascades generated with the binary collision approximation and calibrated to MD results.« less
NASA Astrophysics Data System (ADS)
Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin
2017-06-01
The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.
NASA Astrophysics Data System (ADS)
Borodin, V. A.; Vladimirov, P. V.
2017-12-01
The determination of primary damage production efficiency in metals irradiated with fast neutrons is a complex problem. Typically, the majority of atoms are displaced from their lattice positions not by neutrons themselves, but by energetic primary recoils, that can produce both single Frenkel pairs and dense localized cascades. Though a number of codes are available for the calculation of displacement damage from fast ions, they commonly use binary collision (BC) approximation, which is unreliable for dense cascades and thus tend to overestimate the number of created displacements. In order to amend the radiation damage predictions, this work suggests a combined approach, where the BC approximation is used for counting single Frenkel pairs only, whereas the secondary recoils able to produce localized dense cascades are stored for later processing, but not followed explicitly. The displacement production in dense cascades is then determined independently from molecular dynamics (MD) simulations. Combining contributions from different calculations, one gets the total number of displacements created by particular neutron spectrum. The approach is applied here to the case of beryllium irradiation in a fusion reactor. Using a relevant calculated energy spectrum of primary knocked-on atoms (PKAs), it is demonstrated that more than a half of the primary point defects (˜150/PKA) is produced by low-energy recoils in the form of single Frenkel pairs. The contribution to the damage from the dense cascades as predicted using the mixed BC/MD scheme, i.e. ˜110/PKA, is remarkably lower than the value deduced from uncorrected SRIM calculations (˜145/PKA), so that in the studied case SRIM tends to overpredict the total primary damage level.
Features of primary damage by high energy displacement cascades in concentrated Ni-based alloys
Béland, Laurent Karim; Lu, Chenyang; Osetskiy, Yuri N.; ...
2016-02-25
Alloying of Ni with Fe or Co reduces primary damage production under ion irradiation. Similar results have been obtained from classical molecular dynamics simulations of 1, 10, 20, and 40 keV collision cascades in Ni, NiFe, and NiCo. In all cases, a mix of imperfect stacking fault tetrahedra, faulted loops with a 1/3 {111} Burgers vector, and glissile interstitial loops with a 1/2 {110} Burgers vector were formed, along with small sessile point defect complexes and clusters. Primary damage reduction occurs by three mechanisms. First, Ni-Co, Ni-Fe, Co-Co, and Fe-Fe short-distance repulsive interactions are stiffer than Ni-Ni interactions, which leadmore » to a decrease in damage formation during the transition from the supersonic ballistic regime to the sonic regime. This largely controls final defect production. Second, alloying decreases thermal conductivity, leading to a longer thermal spike lifetime. The associated annealing reduces final damage production. These two mechanisms are especially important at cascades energies less than 40 keV. Third, at the higher energies, the production of large defect clusters by subcascades is inhibited in the alloys. A number of challenges and limitations pertaining to predictive atomistic modeling of alloys under high-energy particle irradiation are discussed.« less
NASA Astrophysics Data System (ADS)
Schenkel, T.; Persaud, A.; Gua, H.; Seidl, P. A.; Waldron, W. L.; Gilson, E. P.; Kaganovich, I. D.; Davidson, R. C.; Friedman, A.; Barnard, J. J.; Minior, A. M.
2014-10-01
We report results from the 2nd generation Neutralized Drift Compression Experiment at Berkeley Lab. NDCX-II is a pulsed, linear induction accelerator designed to drive thin foils to warm dense matter (WDM) states with peak temperatures of ~ 1 eV using intense, short pulses of 1.2 MeV lithium ions. Tunability of the ion beam enables pump-probe studies of radiation effects in solids as a function of excitation density, from isolated collision cascades to the onset of phase-transitions and WDM. Ion channeling is an in situ diagnostic of damage evolution during ion pulses with a sensitivity of <0.1% displacements per atom. We will report results from damage evolution studies in thin silicon crystals with Li + and K + beams. Detection of channeled ions tracks lattice disorder evolution with a resolution of ~ 1 ns using fast current measurements. We will discuss pump-probe experiments with pulsed ion beams and the development of diagnostics for WDM and multi-scale (ms to fs) access to the materials physics of collision cascades e.g. in fusion reactor materials. Work performed under auspices of the US DOE under Contract No. DE-AC02-05CH11231.
HELIUM EFFECTS ON DISPLACEMENT CASCADE IN TUNGSTEN
DOE Office of Scientific and Technical Information (OSTI.GOV)
Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.
2013-09-30
Molecular dynamics (MD) simulations were performed to investigate He effects on displacement cascades in W. Helium content, proportion of interstitial and substitutional He and temperature were varied to reveal the various effects. The effect of interstitial He on the number of self-interstitial atoms (SIAs) produced during cascade damage appears to be insignificant. However, interstitial He tends to fill a vacancy (V). Nevertheless, this process is less favorable than SIA-V recombination particularly when excess SIAs are present before a cascade. The efficiency of He filling and SIA-V recombination increases as temperature increases due to increased point defect mobility. Likewise, substitutional Hemore » is more susceptible to displacement during a collision cascade than W. This susceptibility increases towards higher temperatures. Consequently, the number of surviving V is governed by the interplay between displaced substitutional He and SIA-V recombination. The temperature dependence of these processes results in a minimum number of V reached at an intermediate temperature.« less
NASA Astrophysics Data System (ADS)
Friedland, E.
2017-01-01
At ion energies with inelastic stopping powers less than a few keV/nm, radiation damage is thought to be due to atomic displacements by elastic collisions only. However, it is well known that inelastic processes and non-linear effects due to defect interaction within collision cascades can significantly increase or decrease damage efficiencies. The importance of these processes changes significantly along the ion trajectory and becomes negligible at some distance beyond the projected range, where damage is mainly caused by slowly moving secondary recoils. Hence, in this region amorphization energies should become independent of the ion type and only reflect the properties of the target lattice. To investigate this, damage profiles were obtained from α-particle channeling spectra of 6H-SiC wafers implanted at room temperature with ions in the mass range 84 ⩽ M ⩽ 133, employing the computer code DICADA. An average amorphization dose of (0.7 ± 0.2) dpa and critical damage energy of (17 ± 6) eV/atom are obtained from TRIM simulations at the experimentally observed boundary positions of the amorphous zones.
NASA Astrophysics Data System (ADS)
Seitov, D. D.; Nekrasov, K. A.; Kupryazhkin, A. Ya.; Gupta, S. K.; Akilbekov, A. T.
2017-09-01
The interaction of xenon clusters with the collision cascades in the PuO2 crystals is investigated using the molecular dynamics simulation and the approximation of the pair interaction potentials. The potentials of interaction of Xe atoms with the surrounding particles in the crystal lattice are suggested, that are valid in the range of high collision energies. The cascades created by the recoil 235U ions formed as the plutonium α-decay product are considered, and the influence of such cascades on the structure of the xenon clusters is analyzed. It is shown, that the cascade-cluster interaction leads to release of the xenon atoms from the clusters and their subsequent re-solution in the crystal bulk.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Karabeshkin, K. V., E-mail: yanikolaus@yandex.ru; Karaseov, P. A.; Titov, A. I.
2016-08-15
The depth distributions of structural damage induced in Si at room temperature by the implantation of P and PF{sub 4} with energies from 0.6 to 3.2 keV/amu are experimentally studied in a wide range of doses. It is found that, in all cases, the implantation of molecular PF{sub 4} ions forms practically single-mode defect distributions, with maximum at the target surface. This effect is caused by an increase in the generation of primary defects at the surface of the target. Individual cascades formed by atoms comprising molecule effectively overlap in the surface vicinity; this overlap gives rise to nonlinear processesmore » in combined cascades due to a high density of displacements in such cascades. Quantitative estimation of increase of effectiveness of point defect generation by PF{sub 4} ions in respect to P ions is done on the base of experimental data.« less
Electronic effects in high-energy radiation damage in tungsten
Zarkadoula, Eva; Duffy, Dorothy M.; Nordlund, Kai; ...
2015-03-13
Even though the effects of the electronic excitations during high-energy radiation damage processes are not currently understood, it is shown that their role in the interaction of radiation with matter is important. We perform molecular dynamics simulations of high-energy collision cascades in bcc-tungsten using the coupled two-temperature molecular dynamics (2T-MD) model that incorporates both the effects of electronic stopping and electron–phonon interaction. We compare the combination of these effects on the induced damage with only the effect of electronic stopping, and conclude in several novel insights. In the 2T-MD model, the electron–phonon coupling results in less damage production in themore » molten region and in faster relaxation of the damage at short times. We show these two effects lead to a significantly smaller amount of the final damage at longer times.« less
The role of electronic energy loss in ion beam modification of materials
Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; ...
2014-10-05
The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less
Engineering and Technology Challenges for Active Debris Removal
NASA Technical Reports Server (NTRS)
Liou, Jer-Chyi
2011-01-01
After more than fifty years of space activities, the near-Earth environment is polluted with man-made orbital debris. The collision between Cosmos 2251 and the operational Iridium 33 in 2009 signaled a potential collision cascade effect, also known as the "Kessler Syndrome", in the environment. Various modelling studies have suggested that the commonly-adopted mitigation measures will not be sufficient to stabilize the future debris population. Active debris removal must be considered to remediate the environment. This paper summarizes the key issues associated with debris removal and describes the technology and engineering challenges to move forward. Fifty-four years after the launch of Sputnik 1, satellites have become an integral part of human society. Unfortunately, the ongoing space activities have left behind an undesirable byproduct orbital debris. This environment problem is threatening the current and future space activities. On average, two Shuttle window panels are replaced after every mission due to damage by micrometeoroid or orbital debris impacts. More than 100 collision avoidance maneuvers were conducted by satellite operators in 2010 to reduce the impact risks of their satellites with respect to objects in the U.S. Space Surveillance Network (SSN) catalog. Of the four known accident collisions between objects in the SSN catalog, the last one, collision between Cosmos 2251 and the operational Iridium 33 in 2009, was the most significant. It was the first ever accidental catastrophic destruction of an operational satellite by another satellite. It also signaled the potential collision cascade effect in the environment, commonly known as the "Kessler Syndrome," predicted by Kessler and Cour-Palais in 1978 [1]. Figure 1 shows the historical increase of objects in the SSN catalog. The majority of the catalog objects are 10 cm and larger. As of April 2011, the total objects tracked by the SSN sensors were more than 22,000. However, approximately 6000 of them had yet to be fully processed and entered into the catalog. This population had been dominated by fragmentation debris throughout history. Before the anti-satellite test (ASAT) conducted by China in 2007, the fragmentation debris were almost all explosion fragments. After the ASAT test and the collision between Iridium 33 and Cosmos 2251, the ratio of collision fragments to explosion fragments was about one-to-one. It is expected that accidental collision fragments will further dominate the environment in the future.
NASA Astrophysics Data System (ADS)
Verniero, J. L.; Howes, G. G.
2018-02-01
In space and astrophysical plasmas, violent events or instabilities inject energy into turbulent motions at large scales. Nonlinear interactions among the turbulent fluctuations drive a cascade of energy to small perpendicular scales at which the energy is ultimately converted into plasma heat. Previous work with the incompressible magnetohydrodynamic (MHD) equations has shown that this turbulent energy cascade is driven by the nonlinear interaction between counterpropagating Alfvén waves - also known as Alfvén wave collisions. Direct numerical simulations of weakly collisional plasma turbulence enables deeper insight into the nature of the nonlinear interactions underlying the turbulent cascade of energy. In this paper, we directly compare four cases: both periodic and localized Alfvén wave collisions in the weakly and strongly nonlinear limits. Our results reveal that in the more realistic case of localized Alfvén wave collisions (rather than the periodic case), all nonlinearly generated fluctuations are Alfvén waves, which mediates nonlinear energy transfer to smaller perpendicular scales.
Radiation defect dynamics in Si at room temperature studied by pulsed ion beams
NASA Astrophysics Data System (ADS)
Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.; Myers, M. T.; Shao, L.; Kucheyev, S. O.
2015-10-01
The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ˜4-13 ms and a diffusion length of ˜15-50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wampler, William R., E-mail: wrwampl@sandia.gov; Myers, Samuel M.
A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers,more » and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.« less
Improving atomic displacement and replacement calculations with physically realistic damage models
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nordlund, Kai; Zinkle, Steven J.; Sand, Andrea E.
Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during primary displacement events. The current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model, has nowadays several well-known limitations. In particular, the number of radiation defects produced in energetic cascades in metals is only ~1/3 the NRT-dpa prediction, while the number of atoms involved in atomic mixing is about a factor ofmore » 30 larger than the dpa value. Here we propose two new complementary displacement production estimators (athermal recombination corrected dpa, arc-dpa) and atomic mixing (replacements per atom, rpa) functions that extend the NRT-dpa by providing more physically realistic descriptions of primary defect creation in materials and may become additional standard measures for radiation damage quantification.« less
Improving atomic displacement and replacement calculations with physically realistic damage models
Nordlund, Kai; Zinkle, Steven J.; Sand, Andrea E.; ...
2018-03-14
Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during primary displacement events. The current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model, has nowadays several well-known limitations. In particular, the number of radiation defects produced in energetic cascades in metals is only ~1/3 the NRT-dpa prediction, while the number of atoms involved in atomic mixing is about a factor ofmore » 30 larger than the dpa value. Here we propose two new complementary displacement production estimators (athermal recombination corrected dpa, arc-dpa) and atomic mixing (replacements per atom, rpa) functions that extend the NRT-dpa by providing more physically realistic descriptions of primary defect creation in materials and may become additional standard measures for radiation damage quantification.« less
Improving atomic displacement and replacement calculations with physically realistic damage models.
Nordlund, Kai; Zinkle, Steven J; Sand, Andrea E; Granberg, Fredric; Averback, Robert S; Stoller, Roger; Suzudo, Tomoaki; Malerba, Lorenzo; Banhart, Florian; Weber, William J; Willaime, Francois; Dudarev, Sergei L; Simeone, David
2018-03-14
Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during primary displacement events. The current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model, has nowadays several well-known limitations. In particular, the number of radiation defects produced in energetic cascades in metals is only ~1/3 the NRT-dpa prediction, while the number of atoms involved in atomic mixing is about a factor of 30 larger than the dpa value. Here we propose two new complementary displacement production estimators (athermal recombination corrected dpa, arc-dpa) and atomic mixing (replacements per atom, rpa) functions that extend the NRT-dpa by providing more physically realistic descriptions of primary defect creation in materials and may become additional standard measures for radiation damage quantification.
Radiation defect dynamics in Si at room temperature studied by pulsed ion beams
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wallace, J. B.; Myers, M. T.; Charnvanichborikarn, S.
The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependencemore » of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ∼4–13 ms and a diffusion length of ∼15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.« less
Radiation defect dynamics in Si at room temperature studied by pulsed ion beams
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.
The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here in this paper, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length ismore » revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ~4–13 ms and a diffusion length of ~15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.« less
Radiation defect dynamics in Si at room temperature studied by pulsed ion beams
Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.; ...
2015-10-06
The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here in this paper, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length ismore » revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ~4–13 ms and a diffusion length of ~15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Abdel-Waged, Khaled; Benha University, Faculty of Science, Physics Department; Felemban, Nuha
2011-07-15
We describe how various hadronic cascade models, which are implemented in the geant4 toolkit, describe proton and charged pion transverse momentum spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c, recently measured in the hadron production (HARP) experiment at CERN. The Binary, ultrarelativistic quantum molecular dynamics (UrQMD) and modified FRITIOF (FTF) hadronic cascade models are chosen for investigation. The first two models are based on limited (Binary) and branched (UrQMD) binary scattering between cascade particles which can be either a baryon or meson, in the three-dimensional space of the nucleus, while the latter (FTF) considersmore » collective interactions between nucleons only, on the plane of impact parameter. It is found that the slow (p{sub T}{<=}0.3 GeV/c) proton spectra are quite sensitive to the different treatments of cascade pictures, while the fast (p{sub T}>0.3 GeV/c) proton spectra are not strongly affected by the differences between the FTF and UrQMD models. It is also shown that the UrQMD and FTF combined with Binary (FTFB) models could reproduce both proton and charged pion spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c with the same accuracy.« less
Lycett-Brown, Daniel; Luo, Kai H
2016-11-01
A recently developed forcing scheme has allowed the pseudopotential multiphase lattice Boltzmann method to correctly reproduce coexistence curves, while expanding its range to lower surface tensions and arbitrarily high density ratios [Lycett-Brown and Luo, Phys. Rev. E 91, 023305 (2015)PLEEE81539-375510.1103/PhysRevE.91.023305]. Here, a third-order Chapman-Enskog analysis is used to extend this result from the single-relaxation-time collision operator, to a multiple-relaxation-time cascaded collision operator, whose additional relaxation rates allow a significant increase in stability. Numerical results confirm that the proposed scheme enables almost independent control of density ratio, surface tension, interface width, viscosity, and the additional relaxation rates of the cascaded collision operator. This allows simulation of large density ratio flows at simultaneously high Reynolds and Weber numbers, which is demonstrated through binary collisions of water droplets in air (with density ratio up to 1000, Reynolds number 6200 and Weber number 440). This model represents a significant improvement in multiphase flow simulation by the pseudopotential lattice Boltzmann method in which real-world parameters are finally achievable.
NASA Astrophysics Data System (ADS)
Sahi, Qurat-ul-ain; Kim, Yong-Soo
2018-04-01
The understanding of radiation-induced microstructural defects in body-centered cubic (BCC) iron is of major interest to those using advanced steel under extreme conditions in nuclear reactors. In this study, molecular dynamics (MD) simulations were implemented to examine the primary radiation damage in BCC iron with displacement cascades of energy 1, 5, 10, 20, and 30 keV at temperatures ranging from 100 to 1000 K. Statistical analysis of eight MD simulations of collision cascades were carried out along each [110], [112], [111] and a high index [135] direction and the temperature dependence of the surviving number of point defects and the in-cascade clustering of vacancies and interstitials were studied. The peak time and the corresponding number of defects increase with increasing irradiation temperature and primary knock-on atom (PKA) energy. However, the final number of surviving point defects decreases with increasing lattice temperature. This is associated with the increase of thermal spike at high PKA energy and its long timespan at higher temperatures. Defect production efficiency (i.e., surviving MD defects, per Norgett-Robinson-Torrens displacements) also showed a continuous decrease with the increasing irradiation temperature and PKA energy. The number of interstitial clusters increases with both irradiation temperature and PKA energy. However, the increase in the number of vacancy clusters with PKA energy is minimal-to-constant and decreases as the irradiation temperature increases. Similarly, the probability and cluster size distribution for larger interstitials increase with temperature, whereas only smaller size vacancy clusters were observed at higher temperatures.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Heinisch, H.L.
1997-04-01
The intracascade evolution of the defect distributions of cascades in copper is investigated using stochastic annealing simulations applied to cascades generated with molecular dynamics (MD). The temperature and energy dependencies of annihilation, clustering and free defect production are determined for individual cascades. The annealing simulation results illustrate the strong influence on intracascade evolution of the defect configuration existing in the primary damage state. Another factor significantly affecting the evolution of the defect distribution is the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. This phenomenon introduces a cascade energy dependence of defect evolution that is apparentmore » only beyond the primary damage state, amplifying the need for further study of the annealing phase of cascade evolution and for performing many more MD cascade simulations at higher energies.« less
Singh, Jai
2013-01-01
The objective of this study was a thorough reconsideration, within the framework of Newtonian mechanics and work-energy relationships, of the empirically interpreted relationships employed within the CRASH3 damage analysis algorithm in regards to linearity between barrier equivalent velocity (BEV) or peak collision force magnitude and residual damage depth. The CRASH3 damage analysis algorithm was considered, first in terms of the cases of collisions that produced no residual damage, in order to properly explain the damage onset speed and crush resistance terms. Under the modeling constraints of the collision partners representing a closed system and the a priori assumption of linearity between BEV or peak collision force magnitude and residual damage depth, the equations for the sole realistic model were derived. Evaluation of the work-energy relationships for collisions at or below the elastic limit revealed that the BEV or peak collision force magnitude relationships are bifurcated based upon the residual damage depth. Rather than being additive terms from the linear curve fits employed in the CRASH3 damage analysis algorithm, the Campbell b 0 and CRASH3 AL terms represent the maximum values that can be ascribed to the BEV or peak collision force magnitude, respectively, for collisions that produce zero residual damage. Collisions resulting in the production of non-zero residual damage depth already account for the surpassing of the elastic limit during closure and therefore the secondary addition of the elastic limit terms represents a double accounting of the same. This evaluation shows that the current energy absorbed formulation utilized in the CRASH3 damage analysis algorithm extraneously includes terms associated with the A and G stiffness coefficients. This sole realistic model, however, is limited, secondary to reducing the coefficient of restitution to a constant value for all cases in which the residual damage depth is nonzero. Linearity between BEV or peak collision force magnitude and residual damage depth may be applicable for particular ranges of residual damage depth for any given region of any given vehicle. Within the modeling construct employed by the CRASH3 damage algorithm, the case of uniform and ubiquitous linearity cannot be supported. Considerations regarding the inclusion of internal work recovered and restitution for modeling the separation phase change in velocity magnitude should account for not only the effects present during the evaluation of a vehicle-to-vehicle collision of interest but also to the approach taken for modeling the force-deflection response for each collision partner.
Cascading costs: an economic nitrogen cycle.
Moomaw, William R; Birch, Melissa B L
2005-09-01
The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrified to N(2). We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single ton of nitrogen can cascade through the system, the costs also cascade. Therefore evaluating the benefits of mitigating a ton of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that ton would cascade. The analysis reveals that it is most cost effective to remove a ton of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.
Cascading costs: an economic nitrogen cycle.
Moomaw, William R; Birch, Melissa B L
2005-12-01
The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrified to N2. We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single tonne of nitrogen can cascade through the system, the costs also cascade. Therefore evaluating the benefits of mitigating a tonne of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that tonne would cascade. The analysis reveals that it is most cost effective to remove a tonne of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.
Béland, Laurent Karim; Osetsky, Yuri N.; Stoller, Roger E.
2016-06-23
Previous experimental and theoretical studies suggest that the production of extended defect structures by collision cascades is inhibited in equiatomic NiFe, in comparison to pure Ni. It is also known that the production of such extend defect structures results from the formation of subcascades by high-energy recoils and their subsequent interaction. A detailed analysis of the ballistics of 40 keV cascades in Ni and NiFe is performed to identify the formation of such subcascades and to assess their spatial distribution. It is found that subcascades in Ni and NiFe are created with nearly identical energies and distributed similarly in space.more » This suggests that the differences in production of extended defect structures is not related to processes taking place in the ballistic phase of the collision cascade. Lastly, these results can be generalized to other, more chemically complex, concentrated alloys where the elements have similar atomic numbers, such as many high-entropy alloys.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Béland, Laurent Karim; Osetsky, Yuri N.; Stoller, Roger E.
Previous experimental and theoretical studies suggest that the production of extended defect structures by collision cascades is inhibited in equiatomic NiFe, in comparison to pure Ni. It is also known that the production of such extend defect structures results from the formation of subcascades by high-energy recoils and their subsequent interaction. A detailed analysis of the ballistics of 40 keV cascades in Ni and NiFe is performed to identify the formation of such subcascades and to assess their spatial distribution. It is found that subcascades in Ni and NiFe are created with nearly identical energies and distributed similarly in space.more » This suggests that the differences in production of extended defect structures is not related to processes taking place in the ballistic phase of the collision cascade. Lastly, these results can be generalized to other, more chemically complex, concentrated alloys where the elements have similar atomic numbers, such as many high-entropy alloys.« less
Toward understanding dynamic annealing processes in irradiated ceramics
NASA Astrophysics Data System (ADS)
Myers, Michael Thomas
High energy particle irradiation inevitably generates defects in solids in the form of collision cascades. The ballistic formation and thermalization of cascades occur rapidly and are believed to be reasonably well understood. However, knowledge of the evolution of defects after damage cascade thermalization, referred to as dynamic annealing, is quite limited. Unraveling the mechanisms associated with dynamic an- nealing is crucial since such processes play an important role in the formation of stable post-irradiation disorder in ion-beam-processed semiconductors and determines the "radiation tolerance" of many nuclear materials. The purpose of this dissertation is to further our understanding of the processes involved in dynamic annealing. In order to achieve this, two main tasks are undertaken. First, the effects of dynamic annealing are investigated in ZnO, a technologically relevant material that exhibits very high dynamic defect annealing at room temper- ature. Such high dynamic annealing leads to unusual defect accumulation in heavy ion bombarded ZnO. Through this work, the puzzling features that were observed more than a decade ago in ion-channeling spectra have finally been explained. We show that the presence of a polar surface substantially alters damage accumulation. Non-polar surface terminations of ZnO are shown to exhibit enhanced dynamic an- nealing compared to polar surface terminated ZnO. Additionally, we demonstrate one method to reduce radiation damage in polar surface terminated ZnO by means of a surface modification. These results advance our efforts in the long-sought-after goal of understanding complex radiation damage processes in ceramics. Second, a pulsed-ion-beam method is developed and demonstrated in the case of Si as a prototypical non-metallic target. Such a method is shown to be a novel experimental technique for direct extraction of dynamic annealing parameters. The relaxation times and effective diffusion lengths of mobile defects during the dynamic annealing process play a vital role in damage accumulation. We demonstrate that these parameters dominate the formation of stable post-irradiation disorder. In Si, a defect lifetime of ˜ 6 ms and a characteristic defect diffusion length of ˜ 30 nm are measured. These results should nucleate future pulsed-beam studies of dynamic defect interaction processes in technologically relevant materials. In particular, un- derstanding length- and time-scales of defect interactions are essential for extending laboratory findings to nuclear material lifetimes and to the time-scales of geological storage of nuclear waste.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mishra, P.; Ghose, D.
The sputter ripple formation in polycrystalline metal thin films of Al, Co, Cu, and Ag has been studied by 16.7 keV Ar{sup +} and O{sub 2}{sup +} ion bombardment as a function of angle of ion incidence. The experimental results show the existence of a critical angle of ion incidence ({theta}{sub c}) beyond which the ripples of wave vectors perpendicular to the projected ion beam direction appear. Monte Carlo simulation (SRIM) is carried out to calculate the depth, longitudinal and lateral straggling widths of energy deposition as these values are crucial in determining the critical angle {theta}{sub c}. It ismore » found that the radial energy distribution of the damage cascade has the maximum slightly away from the ion path in contradiction to the Gaussian distribution and the distribution is better characterized by an exponential function. The lower values of lateral straggling widths as those extracted from the measured critical angles using the Bradley and Harper theory indicate a highly anisotropic deposited-energy distribution.« less
Radiation damage by light- and heavy-ion bombardment of single-crystal LiNbO₃
Huang, Hsu-Cheng; Zhang, Lihua; Malladi, Girish; ...
2015-04-14
In this work, a battery of analytical methods including in situ RBS/C, confocal micro-Raman, TEM/STEM, EDS, AFM, and optical microscopy were used to provide a comparative investigation of light- and heavy-ion radiation damage in single-crystal LiNbO₃. High (~MeV) and low (~100s keV) ion energies, corresponding to different stopping power mechanisms, were used and their associated damage events were observed. In addition, sequential irradiation of both ion species was also performed and their cumulative depth-dependent damage was determined. It was found that the contribution from electronic stopping by high-energy heavy ions gave rise to a lower critical fluence for damage formationmore » than for the case of low-energy irradiation. Such energy-dependent critical fluence of heavy-ion irradiation is two to three orders of magnitude smaller than that for the case of light-ion damage. In addition, materials amorphization and collision cascades were seen for heavy-ion irradiation, while for light ion, crystallinity remained at the highest fluence used in the experiment. The irradiation-induced damage is characterized by the formation of defect clusters, elastic strain, surface deformation, as well as change in elemental composition. In particular, the presence of nanometric-scale damage pockets results in increased RBS/C backscattered signal and the appearance of normally forbidden Raman phonon modes. The location of the highest density of damage is in good agreement with SRIM calculations. (author)« less
Radiation damage by light- and heavy-ion bombardment of single-crystal LiNbO₃
DOE Office of Scientific and Technical Information (OSTI.GOV)
Huang, Hsu-Cheng; Zhang, Lihua; Malladi, Girish
In this work, a battery of analytical methods including in situ RBS/C, confocal micro-Raman, TEM/STEM, EDS, AFM, and optical microscopy were used to provide a comparative investigation of light- and heavy-ion radiation damage in single-crystal LiNbO₃. High (~MeV) and low (~100s keV) ion energies, corresponding to different stopping power mechanisms, were used and their associated damage events were observed. In addition, sequential irradiation of both ion species was also performed and their cumulative depth-dependent damage was determined. It was found that the contribution from electronic stopping by high-energy heavy ions gave rise to a lower critical fluence for damage formationmore » than for the case of low-energy irradiation. Such energy-dependent critical fluence of heavy-ion irradiation is two to three orders of magnitude smaller than that for the case of light-ion damage. In addition, materials amorphization and collision cascades were seen for heavy-ion irradiation, while for light ion, crystallinity remained at the highest fluence used in the experiment. The irradiation-induced damage is characterized by the formation of defect clusters, elastic strain, surface deformation, as well as change in elemental composition. In particular, the presence of nanometric-scale damage pockets results in increased RBS/C backscattered signal and the appearance of normally forbidden Raman phonon modes. The location of the highest density of damage is in good agreement with SRIM calculations. (author)« less
Collisional cascading - The limits of population growth in low earth orbit
NASA Technical Reports Server (NTRS)
Kessler, Donald J.
1991-01-01
Random collisions between made-made objects in earth orbit will lead to a significant source of orbital debris, but there are a number of uncertainties in these models, and additional analysis and data are required to fully characterize the future environment. However, the nature of these uncertainties are such that while the future environment is uncertain, the fact that collisions will control the future environment is less uncertain. The data that already exist is sufficient to show that cascading collisions will control the future debris environment with no, or very minor increases in the current low-earth-orbit population. Two populations control this process: explosion fragments and expended rocket bodies and payloads. Practices are already changing to limit explosions in low earth orbit; it is necessary to begin limiting the number of expended rocket bodies and payloads in orbit.
Lattice thermal conductivity of multi-component alloys
Caro, Magdalena; Béland, Laurent K.; Samolyuk, German D.; ...
2015-06-12
High entropy alloys (HEA) have unique properties including the potential to be radiation tolerant. These materials with extreme disorder could resist damage because disorder, stabilized by entropy, is the equilibrium thermodynamic state. Disorder also reduces electron and phonon conductivity keeping the damage energy longer at the deposition locations, eventually favoring defect recombination. In the short time-scales related to thermal spikes induced by collision cascades, phonons become the relevant energy carrier. In this paper, we perform a systematic study of phonon thermal conductivity in multiple component solid solutions represented by Lennard-Jones (LJ) potentials. We explore the conditions that minimize phonon meanmore » free path via extreme alloy complexity, by varying the composition and the elements (differing in mass, atomic radii, and cohesive energy). We show that alloy complexity can be tailored to modify the scattering mechanisms that control energy transport in the phonon subsystem. Finally, our analysis provides a qualitative guidance for the selection criteria used in the design of HEA alloys with low phonon thermal conductivity.« less
Molecular dynamics simulations of damage production by thermal spikes in Ge
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lopez, Pedro; Pelaz, Lourdes; Santos, Ivan
2012-02-01
Molecular dynamics simulation techniques are used to analyze damage production in Ge by the thermal spike process and to compare the results to those obtained for Si. As simulation results are sensitive to the choice of the inter-atomic potential, several potentials are compared in terms of material properties relevant for damage generation, and the most suitable potentials for this kind of analysis are identified. A simplified simulation scheme is used to characterize, in a controlled way, the damage generation through the local melting of regions in which energy is deposited. Our results show the outstanding role of thermal spikes inmore » Ge, since the lower melting temperature and thermal conductivity of Ge make this process much more efficient in terms of damage generation than in Si. The study is extended to the modeling of full implant cascades, in which both collision events and thermal spikes coexist. Our simulations reveal the existence of bigger damaged or amorphous regions in Ge than in Si, which may be formed by the melting and successive quenching induced by thermal spikes. In the particular case of heavy ion implantation, defect structures in Ge are not only bigger, but they also present a larger net content in vacancies than in Si, which may act as precursors for the growth of voids and the subsequent formation of honeycomb-like structures.« less
Current and Future Impact Risks from Small Debris to Operational Satellites
NASA Technical Reports Server (NTRS)
Liou, Jer-Chyi; Kessler, Don
2011-01-01
The collision between Iridium 33 and Cosmos 2251 in 2009 signaled the potential onset of the collision cascade effect, commonly known as the "Kessler Syndrome", in the low Earth orbit (LEO) region. Recent numerical simulations have shown that the 10 cm and larger debris population in LEO will continue to increase even with a good implementation of the commonly-adopted mitigation measures. This increase is driven by collisions involving large and massive intacts, i.e., rocket bodies and spacecraft. Therefore, active debris removal (ADR) of large and massive intacts with high collision probabilities has been argued as a direct and effective means to remediate the environment in LEO. The major risk for operational satellites in the environment, however, comes from impacts with debris just above the threshold of the protection shields. In general, these are debris in the millimeter to centimeter size regime. Although impacts by these objects are insufficient to lead to catastrophic breakup of the entire vehicle, the damage is certainly severe enough to cause critical failure of the key instruments or the entire payload. The focus of this paper is to estimate the impact risks from 5 mm and 1 cm debris to active payloads in LEO (1) in the current environment and (2) in the future environment based on different projection scenarios, including ADR. The goal of the study is to quantify the benefits of ADR in reducing debris impact risks to operational satellites.
NASA Astrophysics Data System (ADS)
Verniero, J. L.; Howes, G. G.; Klein, K. G.
2018-02-01
In space and astrophysical plasmas, turbulence is responsible for transferring energy from large scales driven by violent events or instabilities, to smaller scales where turbulent energy is ultimately converted into plasma heat by dissipative mechanisms. The nonlinear interaction between counterpropagating Alfvén waves, denoted Alfvén wave collisions, drives this turbulent energy cascade, as recognized by early work with incompressible magnetohydrodynamic (MHD) equations. Recent work employing analytical calculations and nonlinear gyrokinetic simulations of Alfvén wave collisions in an idealized periodic initial state have demonstrated the key properties that strong Alfvén wave collisions mediate effectively the transfer of energy to smaller perpendicular scales and self-consistently generate current sheets. For the more realistic case of the collision between two initially separated Alfvén wavepackets, we use a nonlinear gyrokinetic simulation to show here that these key properties persist: strong Alfvén wavepacket collisions indeed facilitate the perpendicular cascade of energy and give rise to current sheets. Furthermore, the evolution shows that nonlinear interactions occur only while the wavepackets overlap, followed by a clean separation of the wavepackets with straight uniform magnetic fields and the cessation of nonlinear evolution in between collisions, even in the gyrokinetic simulation presented here which resolves dispersive and kinetic effects beyond the reach of the MHD theory.
Atomistic material behavior at extreme pressures
Beland, Laurent K.; Osetskiy, Yury N.; Stoller, Roger E.
2016-08-05
Computer simulations are routinely performed to model the response of materials to extreme environments, such as neutron (or ion) irradiation. The latter involves high-energy collisions from which a recoiling atom creates a so-called atomic displacement cascade. These cascades involve coordinated motion of atoms in the form of supersonic shockwaves. These shockwaves are characterized by local atomic pressures >15 GPa and interatomic distances <2 Å. Similar pressures and interatomic distances are observed in other extreme environment, including short-pulse laser ablation, high-impact ballistic collisions and diamond anvil cells. Displacement cascade simulations using four different force fields, with initial kinetic energies ranging frommore » 1 to 40 keV, show that there is a direct relationship between these high-pressure states and stable defect production. An important shortcoming in the modeling of interatomic interactions at these short distances, which in turn determines final defect production, is brought to light.« less
INCAS: an analytical model to describe displacement cascades
NASA Astrophysics Data System (ADS)
Jumel, Stéphanie; Claude Van-Duysen, Jean
2004-07-01
REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricité de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.
Impact of nuclear transmutations on the primary damage production: The example of Ni based steels
NASA Astrophysics Data System (ADS)
Luneville, Laurence; Sublet, Jean Christphe; Simeone, David
2018-07-01
The recent nuclear evaluations describe more accurately the elastic and inelastic neutron-atoms interactions and allow calculating more realistically primary damage induced by nuclear reactions. Even if these calculations do not take into account relaxation processes occurring at the end of the displacement cascade (calculations are performed within the Binary Collision Approximation), they can accurately describe primary and recoil spectra in different reactors opening the door for simulating aging of nuclear materials with Ion Beam facilities. Since neutrons are only sensitive to isotopes, these spectra must be calculated weighting isotope spectra by the isotopic composition of materials under investigation. To highlight such a point, primary damage are calculated in pure Ni exhibiting a meta-stable isotope produced under neutron flux by inelastic neutron-isotope processes. These calculations clearly point out that the instantaneous primary damage production, the displacement per atom rate (dpa/s), responsible for the micro-structure evolution, strongly depends on the 59N i isotopic fractions closely related to the inelastic neutron isotope processes. Since the isotopic composition of the meta-stable isotope vanishes for large fluences, the long term impact of this isotope does not largely modify drastically the total dpa number in Ni based steels materials irradiate in nuclear plants.
Synchronous parallel spatially resolved stochastic cluster dynamics
Dunn, Aaron; Dingreville, Rémi; Martínez, Enrique; ...
2016-04-23
In this work, a spatially resolved stochastic cluster dynamics (SRSCD) model for radiation damage accumulation in metals is implemented using a synchronous parallel kinetic Monte Carlo algorithm. The parallel algorithm is shown to significantly increase the size of representative volumes achievable in SRSCD simulations of radiation damage accumulation. Additionally, weak scaling performance of the method is tested in two cases: (1) an idealized case of Frenkel pair diffusion and annihilation, and (2) a characteristic example problem including defect cluster formation and growth in α-Fe. For the latter case, weak scaling is tested using both Frenkel pair and displacement cascade damage.more » To improve scaling of simulations with cascade damage, an explicit cascade implantation scheme is developed for cases in which fast-moving defects are created in displacement cascades. For the first time, simulation of radiation damage accumulation in nanopolycrystals can be achieved with a three dimensional rendition of the microstructure, allowing demonstration of the effect of grain size on defect accumulation in Frenkel pair-irradiated α-Fe.« less
NASA Technical Reports Server (NTRS)
Dudkin, V. E.; Kovalev, E. E.; Nefedov, N. A.; Antonchik, V. A.; Bogdanov, S. D.; Ostroumov, V. I.; Benton, E. V.; Crawford, H. J.
1995-01-01
Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM).
Photoexcitation cascade and quantum-relativistic jet formation in graphene
NASA Astrophysics Data System (ADS)
Lewandowski, Cyprian; Levitov, Leonid
Interactions between ultra-relativistic particles can lead to striking behavior in which a high-energy particle creates showers of softer particles characterized by a collimated angular distribution aligned with the particle velocity. These showers, known as jets, are a generic phenomenon relevant for all quantum cascades of linearly dispersing particles. This talk will discuss jets formed upon photoexcitation in graphene, which due to its linear dispersion provides an appealing medium for exploring quantum-relativistic phenomena. We will study the cascade generated by carrier-carrier collisions in photon absorption, wherein a single photon creates an electron-hole (e-h) excitation that decays producing multiple near-collinear secondary e-h excitations. We will argue that the cascade can occur through an off-shell mechanism such that all the particles and holes involved reside outside the energy-momentum dispersion manifold, relieving the bottleneck arising in the on-shell process due to energy and momentum conservation. The characteristics of the jets such as the angular and energy distribution of the particles will be discussed. Photogenerated jets provide an interesting setting to investigate the carrier-carrier collision processes in graphene and other Dirac materials. We acknowledge support of the Center for Integrated Quantum Materials (CIQM) under NSF award DMR-1231319.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.
2015-12-28
We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. We found that taking the electronic energy loss out as a friction term results in reducedmore » damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.« less
Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.
2015-12-29
We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. As a result, we found that taking the electronic energy loss out as a frictionmore » term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.« less
The Ultimate Strength of Double Hull Oil Tanker Due to Grounding and Collision
NASA Astrophysics Data System (ADS)
Izaak Latumahina, Samuel; Zubair Muis Alie, Muhammad; Sitepu, Ganding
2018-02-01
The damaged tanker by grounding and collision may totally collapse if loss its buoyancy, stability and suffer structural failure. The objective of the present study is to investigate the ultimate strength of double hull oil tanker under vertical bending moments due to grounding and collision. The damages are modelled by removing the elements consist of stiffened and unstiffened plates from the damages part. One-frame space of the double hull oil tanker is taken to be analysed. Two damages cases are considered in the analyses those are grounding and collision. The transversal damage extent for grounding are 10%, 25%, 40% and 55%. The groundings are placed at symmetric position on the outer bottom part. For the case of collision, the vertical damage extent are taken as 10%, 20%, 40% and 60%. The transversal damages extent is taken to be B/16 and it is constant for all collision damages. The investigation of the ultimate strength is performed by the Non-Linear Finite Element Analysis method under moment control. The boundary condition is applied with fully constrained on all nodes at the aft-end, while the rigid linked on all nodes is attached at the fore-end with respect to the reference point on the neutral axis. The initial imperfection, welding residual stress and crack are not considered in the analyses. The results obtained by Non-Linear Finite Element Analyses for the ultimate strength are compared with the in-house program using Smith’s method implemented in HULLST. The stress distribution and deformation for every case of damages including intact are also discussed in the present study.
Comments on QCD confinement, DTU model, and hadron-nucleus collisions. [Flux tube model
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chiu, C.B.
1981-04-01
Complementary discussions on the QCD flux tube model and the DTU model in connection with our previous work are given. It is also shown that the recent hadron-nucleus collision model has two important suppression mechanisms for particle production. Within the projectile cascade approximation, the model leads to the prediction of approximate anti ..nu.. universality.
The Assessment of the Ultimate Hull Girder Strength of RO-RO Ship after Damages
NASA Astrophysics Data System (ADS)
Zubair Muis Alie, Muhammad; Sitepu, Ganding; Izaak Latumahin, Samuel
2018-03-01
Many accidents of Ro-Ro ships happen in Indonesia such as collision and grounding. When the collision or grounding takes place on the Ro-Ro ship, the ultimate strength of hull structure after damage becomes decrease. Car and passenger decks are critical location since collision and/or grounding occur. In the present study, the assessment of the ultimate hull girder strength is conducted. The cross section of Ro-Ro ship is taken to be analyzed. The collision and grounding damages are assumed to be palced on the side and bottom area, respectively. The damages are created by removing the element from the side shell and bottom part. Finally, the result obtained is compared with one another.
Enhancement of deuterium retention in damaged tungsten by plasma-induced defect clustering
NASA Astrophysics Data System (ADS)
Jin, Younggil; Roh, Ki-Baek; Sheen, Mi-Hyang; Kim, Nam-Kyun; Song, Jaemin; Kim, Young-Woon; Kim, Gon-Ho
2017-12-01
The enhancement of deuterium retention was investigated for tungsten in the presence of both 2.8 MeV self-ion induced cascade damage and fuel hydrogen isotope plasma. Vacancy clustering in cascade damaged polycrystalline tungsten occurred due to deuterium irradiation and was observed near the grain boundary by using all-step transmission electron microscopy analysis. Analysis of the highest desorption temperature peak using thermal desorption spectroscopy supports reasonable evidence of defect clustering in the damaged polycrystalline tungsten. The defect clustering was neither observed on the damaged polycrystalline tungsten without deuterium irradiation nor on the damaged single-crystalline tungsten with deuterium irradiation. This result implies the synergetic role of deuterium and grain boundary on defect clustering. This study proposes a path for the defect transform from point defect to defect cluster, by the agglomeration between irradiated deuterium and cascade damage-induced defect. This agglomeration may induce more severe damage on the tungsten divertor at which the high fuel hydrogen ions, fast neutrons, and self-ions are irradiated simultaneously and it would increase the in-vessel tritium inventory.
A cascading failure model for analyzing railway accident causation
NASA Astrophysics Data System (ADS)
Liu, Jin-Tao; Li, Ke-Ping
2018-01-01
In this paper, a new cascading failure model is proposed for quantitatively analyzing the railway accident causation. In the model, the loads of nodes are redistributed according to the strength of the causal relationships between the nodes. By analyzing the actual situation of the existing prevention measures, a critical threshold of the load parameter in the model is obtained. To verify the effectiveness of the proposed cascading model, simulation experiments of a train collision accident are performed. The results show that the cascading failure model can describe the cascading process of the railway accident more accurately than the previous models, and can quantitatively analyze the sensitivities and the influence of the causes. In conclusion, this model can assist us to reveal the latent rules of accident causation to reduce the occurrence of railway accidents.
Stewart, James A.; Brookman, G.; Price, Patrick Michael; ...
2018-04-25
In this study, the evolution and characterization of single-isolated-ion-strikes are investigated by combining atomistic simulations with selected-area electron diffraction (SAED) patterns generated from these simulations. Five molecular dynamics simulations are performed for a single 20 keV primary knock-on atom in bulk crystalline Si. The resulting cascade damage is characterized in two complementary ways. First, the individual cascade events are conventionally quantified through the evolution of the number of defects and the atomic (volumetric) strain associated with these defect structures. These results show that (i) the radiation damage produced is consistent with the Norgett, Robinson, and Torrens model of damage productionmore » and (ii) there is a net positive volumetric strain associated with the cascade structures. Second, virtual SAED patterns are generated for the resulting cascade-damaged structures along several zone axes. The analysis of the corresponding diffraction patterns shows the SAED spots approximately doubling in size, on average, due to broadening induced by the defect structures. Furthermore, the SAED spots are observed to exhibit an average radial outward shift between 0.33% and 0.87% depending on the zone axis. Finally, this characterization approach, as utilized here, is a preliminary investigation in developing methodologies and opportunities to link experimental observations with atomistic simulations to elucidate microstructural damage states.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Stewart, James A.; Brookman, G.; Price, Patrick Michael
In this study, the evolution and characterization of single-isolated-ion-strikes are investigated by combining atomistic simulations with selected-area electron diffraction (SAED) patterns generated from these simulations. Five molecular dynamics simulations are performed for a single 20 keV primary knock-on atom in bulk crystalline Si. The resulting cascade damage is characterized in two complementary ways. First, the individual cascade events are conventionally quantified through the evolution of the number of defects and the atomic (volumetric) strain associated with these defect structures. These results show that (i) the radiation damage produced is consistent with the Norgett, Robinson, and Torrens model of damage productionmore » and (ii) there is a net positive volumetric strain associated with the cascade structures. Second, virtual SAED patterns are generated for the resulting cascade-damaged structures along several zone axes. The analysis of the corresponding diffraction patterns shows the SAED spots approximately doubling in size, on average, due to broadening induced by the defect structures. Furthermore, the SAED spots are observed to exhibit an average radial outward shift between 0.33% and 0.87% depending on the zone axis. Finally, this characterization approach, as utilized here, is a preliminary investigation in developing methodologies and opportunities to link experimental observations with atomistic simulations to elucidate microstructural damage states.« less
NASA Astrophysics Data System (ADS)
Stewart, J. A.; Brookman, G.; Price, P.; Franco, M.; Ji, W.; Hattar, K.; Dingreville, R.
2018-04-01
The evolution and characterization of single-isolated-ion-strikes are investigated by combining atomistic simulations with selected-area electron diffraction (SAED) patterns generated from these simulations. Five molecular dynamics simulations are performed for a single 20 keV primary knock-on atom in bulk crystalline Si. The resulting cascade damage is characterized in two complementary ways. First, the individual cascade events are conventionally quantified through the evolution of the number of defects and the atomic (volumetric) strain associated with these defect structures. These results show that (i) the radiation damage produced is consistent with the Norgett, Robinson, and Torrens model of damage production and (ii) there is a net positive volumetric strain associated with the cascade structures. Second, virtual SAED patterns are generated for the resulting cascade-damaged structures along several zone axes. The analysis of the corresponding diffraction patterns shows the SAED spots approximately doubling in size, on average, due to broadening induced by the defect structures. Furthermore, the SAED spots are observed to exhibit an average radial outward shift between 0.33% and 0.87% depending on the zone axis. This characterization approach, as utilized here, is a preliminary investigation in developing methodologies and opportunities to link experimental observations with atomistic simulations to elucidate microstructural damage states.
Calculation of shear viscosity using Green-Kubo relations within a parton cascade
NASA Astrophysics Data System (ADS)
Wesp, C.; El, A.; Reining, F.; Xu, Z.; Bouras, I.; Greiner, C.
2011-11-01
The shear viscosity of a gluon gas is calculated using the Green-Kubo relation. Time correlations of the energy-momentum tensor in thermal equilibrium are extracted from microscopic simulations using a parton cascade solving various Boltzmann collision processes. We find that the perturbation-QCD- (pQCD-) based gluon bremsstrahlung described by Gunion-Bertsch processes significantly lowers the shear viscosity by a factor of 3 to 8 compared to elastic scatterings. The shear viscosity scales with the coupling as η˜1/[αs2log(1/αs)]. For constant αs the shear viscosity to entropy density ratio η/s has no dependence on temperature. Replacing the pQCD-based collision angle distribution of binary scatterings by an isotropic form decreases the shear viscosity by a factor of 3.
DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN AT 1025 K
DOE Office of Scientific and Technical Information (OSTI.GOV)
Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.
2013-09-30
Molecular dynamics simulation was employed to investigate the irradiation damage properties of bulk tungsten at 1025 K (0.25 melting temperature). A comprehensive data set of primary cascade damage was generated up to primary knock-on atom (PKA) energies 100 keV. The dependence of the number of surviving Frenkel pairs (NFP) on the PKA energy (E) exhibits three different characteristic domains presumably related to the different cascade morphologies that form. The low-energy regime < 0.2 keV is characterized by a hit-or-miss type of Frenkel pair (FP) production near the displacement threshold energy of 128 eV. The middle regime 0.3 – 30 keVmore » exhibits a sublinear dependence of log(NFP) vs log(E) associated with compact cascade morphology with a slope of 0.73. Above 30 keV, the cascade morphology consists of complex branches or interconnected damage regions. In this extended morphology, large interstitial clusters form from superposition of interstitials from nearby damage regions. Strong clustering above 30 keV results in a superlinear dependence of log(NFP) vs log(E) with a slope of 1.365. At 100 keV, an interstitial cluster of size 92 and a vacancy cluster of size 114 were observed.« less
NASA Astrophysics Data System (ADS)
Zhusubaliyev, Zhanybai T.; Avrutin, Viktor; Rubanov, Vasily G.; Bushuev, Dmitry A.; Titov, Dmitry V.; Yanochkina, Olga O.
2018-05-01
The paper describes a new scenario for the transition to complex dynamics in a vibrating system with an unbalanced rotor and a relay feedback control. We show that the transition from a regular dynamics without switching events in the relay element to an irregular dynamics which takes place completely in the hysteresis region occurs via a cascade of persistence border collisions.
Energy behavior on side structure in event of ship collision subjected to external parameters.
Prabowo, Aditya Rio; Bae, Dong Myung; Sohn, Jung Min; Cao, Bo
2016-11-01
The safety of ships in regards to collisions and groundings, as well as the navigational and structural aspects of ships, has been improved and developed up to this day by technical, administrative and nautical parties. The damage resulting from collisions could be reduced through several techniques such as designing appropriate hull structures, ensuring tightness of cargo tanks as well as observation and review on structural behaviors, whilst accounting for all involved parameters. The position during a collision can be influenced by the collisions' location and angle as these parts are included in the external dynamics of ship collisions. In this paper, the results of several collision analyses using the finite element method were used and reviewed regarding the effect of location and angle on energy characteristic. Firstly, the capabilities of the structure and its ability to resist destruction in a collision process were presented and comparisons were made to other collision cases. Three types of collisions were identified based on the relative location of contact points to each other. From the results, it was found that the estimation of internal energy by the damaged ships differed in range from 12%-24%. In the second stage, the results showed that a collision between 30 to 60 degrees produced higher level energy than a collision in the perpendicular position. Furthermore, it was concluded that striking and struck objects in collision contributed to energy and damage shape.
NASA Technical Reports Server (NTRS)
Sako, H.; Ahle, L.; Akiba, Y.; Ashktorab, K.; Baker, M. D.; Beavis, D.; Britt, H. C.; Chang, J.; Chasman, C.; Chen, Z.;
1997-01-01
Antiproton production in heavy ion collisions reflects subtle interplay between initial production and absorption by nucleons. Because the AGS energies (10--20 A(center-dot)GeV/c) are close to the antiproton production threshold, antiproton may be sensitive to cooperative processes such as QGP and hadronic multi-step processes. On the other hand, antiproton has been proposed as a probe of baryon density due to large N(anti N) annihilation cross sections. Cascade models predict the maximum baryon density reaches about 10 times the normal nucleus density in central Au+Au collisions, where the strong antiproton absorption is expected. In this paper, the authors show systematic studies of antiproton production from p+A to Au+Au collisions.
On the Treatment of l-changing Proton-hydrogen Rydberg Atom Collisions
NASA Astrophysics Data System (ADS)
Vrinceanu, Daniel; Onofrio, Roberto; Sadeghpour, Hossein
2018-01-01
Energy-conserving, angular momentum-changing collisions between protons and highly excited Rydberg hydrogen atoms are important for precise understanding of the primordial recombination cascade, and the elemental abundance.Early approaches to l-changing collisions used perturbation theory for only dipole-allowed (Δl = ±1) transitions. An exact non-perturbative quantum mechanical treatment is possible, but it comes at computational cost for highly excited Rydberg states. In this note we show how to obtain a semi-classical limit that is accurate and simple, and develop further physical insights afforded by the non-perturbative quantum mechanical treatment.
A time-dependent probabilistic seismic-hazard model for California
Cramer, C.H.; Petersen, M.D.; Cao, T.; Toppozada, Tousson R.; Reichle, M.
2000-01-01
For the purpose of sensitivity testing and illuminating nonconsensus components of time-dependent models, the California Department of Conservation, Division of Mines and Geology (CDMG) has assembled a time-dependent version of its statewide probabilistic seismic hazard (PSH) model for California. The model incorporates available consensus information from within the earth-science community, except for a few faults or fault segments where consensus information is not available. For these latter faults, published information has been incorporated into the model. As in the 1996 CDMG/U.S. Geological Survey (USGS) model, the time-dependent models incorporate three multisegment ruptures: a 1906, an 1857, and a southern San Andreas earthquake. Sensitivity tests are presented to show the effect on hazard and expected damage estimates of (1) intrinsic (aleatory) sigma, (2) multisegment (cascade) vs. independent segment (no cascade) ruptures, and (3) time-dependence vs. time-independence. Results indicate that (1) differences in hazard and expected damage estimates between time-dependent and independent models increase with decreasing intrinsic sigma, (2) differences in hazard and expected damage estimates between full cascading and not cascading are insensitive to intrinsic sigma, (3) differences in hazard increase with increasing return period (decreasing probability of occurrence), and (4) differences in moment-rate budgets increase with decreasing intrinsic sigma and with the degree of cascading, but are within the expected uncertainty in PSH time-dependent modeling and do not always significantly affect hazard and expected damage estimates.
Nanodust released in interplanetary collisions
NASA Astrophysics Data System (ADS)
Lai, H. R.; Russell, C. T.
2018-07-01
The lifecycle of near-Earth objects (NEOs) involves a collisional cascade that produces ever smaller debris ending with nanoscale particles which are removed from the solar system by radiation pressure and electromagnetic effects. It has been proposed that the nanodust clouds released in collisions perturb the background interplanetary magnetic field and create the interplanetary field enhancements (IFEs). Assuming that this IFE formation scenario is actually operating, we calculate the interplanetary collision rate, estimate the total debris mass carried by nanodust, and compare the collision rate with the IFE rate. We find that to release the same amount of nanodust, the collision rate is comparable to the observed IFE rate. Besides quantitatively testing the association between the collisions evolving large objects and giant solar wind structures, such a study can be extended to ranges of smaller scales and to investigate the source of moderate and small solar wind perturbations.
Renormalization of the fragmentation equation: exact self-similar solutions and turbulent cascades.
Saveliev, V L; Gorokhovski, M A
2012-12-01
Using an approach developed earlier for renormalization of the Boltzmann collision integral [Saveliev and Nanbu, Phys. Rev. E 65, 051205 (2002)], we derive an exact divergence form for the fragmentation operator. Then we reduce the fragmentation equation to the continuity equation in size space, with the flux given explicitly. This allows us to obtain self-similar solutions and to find the integral of motion for these solutions (we call it the bare flux). We show how these solutions can be applied as a description of cascade processes in three- and two-dimensional turbulence. We also suggested an empirical cascade model of impact fragmentation of brittle materials.
DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN UP TO 200 KEV OF DAMAGE ENERGY AT 300, 1025, AND 2050 K
DOE Office of Scientific and Technical Information (OSTI.GOV)
Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.
2015-09-22
We generated molecular dynamics database of primary defects that adequately covers the range of tungsten recoil energy imparted by 14-MeV neutrons. During this semi annual period, cascades at 150 and 200 keV at 300 and 1025 K were simulated. Overall, we included damage energy up to 200 keV at 300 and 1025 K, and up to 100 keV at 2050 K. We report the number of surviving Frenkel pairs (NF) and the size distribution of defect clusters. The slope of the NF curve versus cascade damage energy (EMD), on a log-log scale, changes at a transition energy (μ). For EMDmore » > μ, the cascade forms interconnected damage regions that facilitate the formation of large clusters of defects. At 300 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 266 and 335, respectively. Similarly, at 1025 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 296 and 338, respectively. At 2050 K, large interstitial clusters also routinely form, but practically no large vacancy clusters do« less
Evaluation of Repair Techniques for Impact-Damaged Prestressed Beams
DOT National Transportation Integrated Search
2018-05-01
Collisions between over-height vehicles and bridges occur about 1,000 times per year in the United States. Collision damage to bridges can range from minor to catastrophic, potentially requiring repair or replacement of a bridge beam. For prestressed...
ERIC Educational Resources Information Center
Ontario Ministry of Skills Development, Toronto.
This manual presents training standards for auto body and collision damage repairers (branch 1) and is intended to be used by apprentice/trainees, instructors, and companies in Ontario, Canada as a blueprint for training or as a prerequisite for accreditation/certification. The training standards identify skills required for this occupation and…
Evaluation of repair techniques for impact-damaged prestressed beams : final report.
DOT National Transportation Integrated Search
2017-04-01
Collisions between over height vehicles and bridges occur about 1,000 times per year in the United States. Collision damage to : bridges can range from minor to catastrophic, potentially requiring repair or replacement of a bridge beam. For prestress...
NASA Astrophysics Data System (ADS)
Tsirkunov, Yu. M.; Romanyuk, D. A.; Panfilov, S. V.
2011-10-01
Time-dependent two-dimensional (2D) flow of dusty gas through a set of two cascades of airfoils (blades) has been studied numerically. The first cascade was assumed to move (rotor) and the second one to be immovable (stator). Such a flow can be considered, in some sense, as a flow in the inlet stage of a turbomachine, for example, in the inlet compressor of an aircraft turbojet engine. Dust particle concentration was assumed to be very low, so that the interparticle collisions and the effect of the dispersed phase on the carrier gas were negligible. Flow of the carrier gas was described by full Navier-Stokes equations. In calculations of particle motion, the particles were considered as solid spheres. The particle drag force, transverse Magnus force, and damping torque were taken into account in the model of gas-particle interaction. The impact interaction of particles with blades was considered as frictional and partly elastic. The effects of particle size distribution and particle scattering in the course of particle-blade collisions were investigated. Flow fields of the carrier gas and flow patterns of the particle phase were obtained and discussed.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Matthews, D.L.; Fortner, R.J.; Schneider, D.
Recent measurements of the x-ray and Auger line strengths in Li-like neon produced by 45-MeV Cl/sup 13+/ ..-->.. Ne collisions are compared with theoretical values. We assume that in the collision there is a statistical population of configurations and multiplet states. An overpopulation of the 1s2s/sup 2/ and 1s2s2p configurations (relative to the 1s2p/sup 2/) is observed. We suggest cascade feeding as a likely mechanism for producing this effect. (AIP)
Production of Pions in pA-collisions
NASA Technical Reports Server (NTRS)
Moskalenko, I. V.; Mashnik, S. G.
2003-01-01
Accurate knowledge of pion production cross section in PA-collisions is of interest for astrophysics, CR physics, and space radiation studies. Meanwhile, pion production in pA-reactions is often accounted for by simple scaling of that for pp-collisions, which is not enough for many real applications. We evaluate the quality of existing parameterizations using the data and simulations with the Los Alamos version of the Quark-Gluon String Model code LAQGSM and the improved Cascade-Exciton Model code CEM2k. The LAQGSM and CEM2k models have been shown to reproduce well nuclear reactions and hadronic data in the range 0.01-800 GeV/nucleon.
Momentum loss in proton-nucleus and nucleus-nucleus collisions
NASA Technical Reports Server (NTRS)
Khan, Ferdous; Townsend, Lawrence W.
1993-01-01
An optical model description, based on multiple scattering theory, of longitudinal momentum loss in proton-nucleus and nucleus-nucleus collisions is presented. The crucial role of the imaginary component of the nucleon-nucleon transition matrix in accounting for longitudinal momentum transfer is demonstrated. Results obtained with this model are compared with Intranuclear Cascade (INC) calculations, as well as with predictions from Vlasov-Uehling-Uhlenbeck (VUU) and quantum molecular dynamics (QMD) simulations. Comparisons are also made with experimental data where available. These indicate that the present model is adequate to account for longitudinal momentum transfer in both proton-nucleus and nucleus-nucleus collisions over a wide range of energies.
Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC
Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; ...
2015-06-18
Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombinationmore » when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.« less
Nucleon shadowing effects in Cu + Cu and Au + Au collisions at RHIC within the HIJING code
NASA Astrophysics Data System (ADS)
Abdel-Waged, Khaled; Felemban, Nuha
2018-02-01
The centrality dependence of pseudorapidity density of charged particles ({{{d}}{N}}{{ch}}/{{d}}η ) in Cu + Cu (Au + Au) collisions at Relativistic Heavy Ion Collider energy of \\sqrt{{s}{{NN}}}=22.4, 62.4 and 200 (19.6, 62.4 and 200) GeV, is investigated within an improved HIJING code. The standard HIJING model is enhanced by a prescription for collective nucleon-nucleon (NN) interactions and more modern parton distribution functions. The collective NN-interactions are used to induce both cascade and nucleon shadowing effects. We find collective cascade broadens the pseudorapidity distributions in the tails (at | η | > {y}{beam}) above 25%-30% collision centrality to be consistent with the {{{d}}{N}}{{ch}}/{{d}}η data at \\sqrt{{s}{{NN}}} =19.6,22.4,62.4 {GeV}. The overall contribution of nucleon shadowing is shown to depress the whole shape of {{{d}}{N}}{{ch}}/{{d}}η in the primary interaction region (at | η | < {y}{beam}) for semiperipheral (20%-25%) and peripheral (≥slant 35 % {--}40 % ) Cu + Cu (Au + Au) interactions at \\sqrt{{s}{{NN}}}=200 {GeV}, in accordance with the PHOBOS data.
Cascade morphology transition in bcc metals
DOE Office of Scientific and Technical Information (OSTI.GOV)
Setyawan, Wahyu; Selby, A.; Juslin, Niklas
2015-06-10
Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent,more » $b$, in the defect production curve as a function of cascade energy ($$N_F$$$ \\sim$$$E_{MD}^b$$). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, $$\\mu$$, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of $$\\mu$$ as a function of displacement threshold energy, $$E_d$$, is presented for bcc metals.« less
Renormalization of the fragmentation equation: Exact self-similar solutions and turbulent cascades
NASA Astrophysics Data System (ADS)
Saveliev, V. L.; Gorokhovski, M. A.
2012-12-01
Using an approach developed earlier for renormalization of the Boltzmann collision integral [Saveliev and Nanbu, Phys. Rev. E1539-375510.1103/PhysRevE.65.051205 65, 051205 (2002)], we derive an exact divergence form for the fragmentation operator. Then we reduce the fragmentation equation to the continuity equation in size space, with the flux given explicitly. This allows us to obtain self-similar solutions and to find the integral of motion for these solutions (we call it the bare flux). We show how these solutions can be applied as a description of cascade processes in three- and two-dimensional turbulence. We also suggested an empirical cascade model of impact fragmentation of brittle materials.
Cascade morphology transition in bcc metals
Setyawan, Wahyu; Selby, Aaron P.; Juslin, Niklas; ...
2015-05-18
Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (N-F similar to E-MD(b)). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, mu, between the high-and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of mu as a function of displacement threshold energy, E-d,more » is presented for bcc metals.« less
Effects of electronic excitation on cascade dynamics in nickel–iron and nickel–palladium systems
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zarkadoula, Eva; Samolyuk, German; Weber, William J.
Using molecular dynamics simulations and the two-temperature model, we provide in this paper a comparison of the surviving damage from single ion irradiation events in nickel-based alloys, for cascades with and without taking into account the effects of the electronic excitations. We find that including the electronic effects impacts the amount of the resulting damage and the production of isolated defects. Finally, irradiation of nickel–palladium systems results in larger numbers of defects compared to nickel–iron systems, with similar numbers of isolated defects. We additionally investigate the mass effect on the two-temperature model in molecular dynamics simulations of cascades.
Effects of electronic excitation on cascade dynamics in nickel–iron and nickel–palladium systems
Zarkadoula, Eva; Samolyuk, German; Weber, William J.
2017-06-10
Using molecular dynamics simulations and the two-temperature model, we provide in this paper a comparison of the surviving damage from single ion irradiation events in nickel-based alloys, for cascades with and without taking into account the effects of the electronic excitations. We find that including the electronic effects impacts the amount of the resulting damage and the production of isolated defects. Finally, irradiation of nickel–palladium systems results in larger numbers of defects compared to nickel–iron systems, with similar numbers of isolated defects. We additionally investigate the mass effect on the two-temperature model in molecular dynamics simulations of cascades.
Intermittency in heavy ion collisions
NASA Astrophysics Data System (ADS)
Murray, Michael; HELIOS Collaboration
1991-04-01
This paper describes a study of multiplicity and transverse energy fluctuations using factorial moments for sulphur collisions with silver — bromide emulsion and platinium targets at 200 GeV/A. The data were taken with the HELIOS experiment at CERN. Bialas and Peschanski [1] predicted a power law dependence of the moments on the rapidity bin size if the fluctuations are invariant over a range of scales. This pattern is known as intermittency in the theory of turbulence, and indicates a fractal structure. Fluctuations were studied for a range of pseudorapidity scales using scaled factorial moments. Correlated fluctuations were studied using correlated scaled factorial moments. For peripheral collisions the data are weakly intermittent and consistent with a simple cascading mechanism, the a model. For central collisions no clear signal of intermittency was seen.
Intermittency in heavy ion collisions
NASA Astrophysics Data System (ADS)
1991-04-01
This paper describes a study of multiplicity and transverse energy fluctuations using factorial moments for sulphur collisions with silver - bromide emulsion and platinium targets at 200 GeV/A. The data were taken with the HELIOS experiment at CERN. Bialas and Peschanski [1] predicted a power law dependence of the moments on the rapidity bin size if the fluctuations are invariant over a range of scales. This pattern is known as intermittency in the theory of turbulence, and indicates a fractal structure. Fluctuations were studied for a range of pseudorapidity scales using scaled factorial moments. Correlated fluctuations were studied using correlated scaled factorial moments. For peripheral collisions the data are weakly intermittent and consistent with a simple cascading mechanism, the a model. For central collisions no clear signal of intermittency was seen.
NASA Technical Reports Server (NTRS)
Dudkin, V. E.; Kovalev, E. E.; Nefedov, N. A.; Antonchik, V. A.; Bogdanov, S. D.; Kosmach, V. F.; Likhachev, A. YU.; Benton, E. V.; Crawford, H. J.
1995-01-01
A method is proposed for finding the dependence of mean multiplicities of secondaries on the nucleus-collision impact parameter from the data on the total interaction ensemble. The impact parameter has been shown to completely define the mean characteristics of an individual interaction event. A difference has been found between experimental results and the data calculated in terms of the cascade-evaporation model at impact-parameter values below 3 fm.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wampler, William R.; Myers, Samuel M.
2014-02-01
A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defectsmore » within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.« less
Computer simulations of disordering kinetics in irradiated intermetallic compounds
DOE Office of Scientific and Technical Information (OSTI.GOV)
Spaczer, M.; Caro, A.; Victoria, M.
1994-11-01
Molecular-dynamics computer simulations of collision cascades in intermetallic Cu[sub 3]Au, Ni[sub 3]Al, and NiAl have been performed to study the nature of the disordering processes in the collision cascade. The choice of these systems was suggested by the quite accurate description of the thermodynamic properties obtained using embedded-atom-type potentials. Since melting occurs in the core of the cascades, interesting effects appear as a result of the superposition of the loss (and subsequent recovery) of the crystalline order and the evolution of the chemical order, both processes being developed on different time scales. In our previous simulations on Ni[sub 3]Al andmore » Cu[sub 3]Au [T. Diaz de la Rubia, A. Caro, and M. Spaczer, Phys. Rev. B 47, 11 483 (1993)] we found a significant difference between the time evolution of the chemical short-range order (SRO) and the crystalline order in the cascade core for both alloys, namely the complete loss of the crystalline structure but only partial chemical disordering. Recent computer simulations in NiAl show the same phenomena. To understand these features we study the liquid phase of these three alloys and present simulation results concerning the dynamical melting of small samples, examining the atomic mobility, the relaxation time, and the saturation value of the chemical short-range order. An analytic model for the time evolution of the SRO is given.« less
DOT National Transportation Integrated Search
2016-07-31
This report presents a novel framework for promptly assessing the probability of barge-bridge : collision damage of piers based on probabilistic-based classification through machine learning. The main : idea of the presented framework is to divide th...
77 FR 62435 - Inland Waterways Navigation Regulations
Federal Register 2010, 2011, 2012, 2013, 2014
2012-10-15
... collisions and groundings. (See 33 CFR 162.130(a)). Second, it is intended to limit wake damage to vessels... D33 stationary light is not necessary to prevent wake damage or to prevent collisions and groundings... Justice Reform, to minimize litigation, eliminate ambiguity, and reduce burden. 9. Protection of Children...
Fragmentation of displacement cascades into subcascades: A molecular dynamics study
Antoshchenkova, E.; Luneville, L.; Simeone, D.; ...
2014-12-12
The fragmentation of displacement cascades into subcascades in copper and iron has been investigated through the molecular dynamics technique. A two-point density correlation function has been used to analyze the cascades as a function of the primary knock-on (PKA) energy. This approach is used as a tool for detecting subcascade formation. The fragmentation can already be identified at the end of the ballistic phase. Its resulting evolution in the peak damage state discriminates between unconnected and connected subcascades. The damage zone at the end of the ballistic phase is the precursor of the extended regions that contain the surviving defects.more » A fractal analysis of the cascade exhibits a dependence on both the stage of the cascade development and the PKA energy. This type of analysis enables the minimum and maximum displacement spike energies together with the subcascade formation threshold energy to be determined. (C) 2014 Elsevier B.V. All rights reserved.« less
Fragmentation of displacement cascades into subcascades: A molecular dynamics study
DOE Office of Scientific and Technical Information (OSTI.GOV)
Antoshchenkova, E.; Luneville, L.; Simeone, D.
The fragmentation of displacement cascades into subcascades in copper and iron has been investigated through the molecular dynamics technique. A two-point density correlation function has been used to analyze the cascades as a function of the primary knock-on (PKA) energy. This approach is used as a tool for detecting subcascade formation. The fragmentation can already be identified at the end of the ballistic phase. Its resulting evolution in the peak damage state discriminates between unconnected and connected subcascades. The damage zone at the end of the ballistic phase is the precursor of the extended regions that contain the surviving defects.more » A fractal analysis of the cascade exhibits a dependence on both the stage of the cascade development and the PKA energy. This type of analysis enables the minimum and maximum displacement spike energies together with the subcascade formation threshold energy to be determined. (C) 2014 Elsevier B.V. All rights reserved.« less
Effects of two-temperature model on cascade evolution in Ni and NiFe
Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; ...
2016-07-05
We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic effects are more profound in the higher-energy cascades, and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than in Ni.
Lu, Chenyang; Jin, Ke; Béland, Laurent K; Zhang, Feifei; Yang, Taini; Qiao, Liang; Zhang, Yanwen; Bei, Hongbin; Christen, Hans M; Stoller, Roger E; Wang, Lumin
2016-02-01
Energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters far exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance.
Lu, Chenyang; Jin, Ke; Béland, Laurent K.; Zhang, Feifei; Yang, Taini; Qiao, Liang; Zhang, Yanwen; Bei, Hongbin; Christen, Hans M.; Stoller, Roger E.; Wang, Lumin
2016-01-01
Energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters far exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance. PMID:26829570
Fabrication of phonon-based metamaterial structures using focused ion beam patterning
NASA Astrophysics Data System (ADS)
Bassim, Nabil D.; Giles, Alexander J.; Ocola, Leonidas E.; Caldwell, Joshua D.
2018-02-01
The focused ion beam (FIB) is a powerful tool for rapid prototyping and machining of functional nanodevices. It is employed regularly to fabricate test metamaterial structures but, to date, has been unsuccessful in fabricating metamaterial structures with features at the nanoscale that rely on surface phonons as opposed to surface plasmons because of the crystalline damage that occurs with the collision cascade associated with ion sputtering. In this study, we employ a simple technique of protecting the crystalline substrate in single-crystal 4H-SiC to design surface phonon polariton-based optical resonance structures. By coating the material surface with a thin film of chromium, we have placed a material of high sputter resistance on the surface, which essentially absorbs the energy in the beam tails. When the beam ultimately punches through the Cr film, the hard walls in the film have the effect of channeling the beam to create smooth sidewalls. This demonstration opens the possibility of further rapid-prototyping of metamaterials using FIB.
A toolkit of measures for reducing animal-vehicle collisions.
DOT National Transportation Integrated Search
2006-01-01
Animal-vehicle collisions are a growing concern in terms of human safety; costs related to injury, property damage, and disposal; and the viability of wildlife populations. These collisions are rapidly increasing throughout the United States, and Vir...
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gerboth, Matthew D.; Setyawan, Wahyu; Henager, Charles H.
2014-01-07
A method is established and validated using molecular dynamics (MD) to determine the displacement threshold energies as Ed in nanolayered, multilayered systems of dissimilar metals. The method is applied to specifically oriented nanolayered films of Al-Ti where the crystal structure and interface orientations are varied in atomic models and Ed is calculated. Methods for defect detection are developed and discussed based on prior research in the literature and based on specific crystallographic directions available in the nanolayered systems. These are compared and contrasted to similar calculations in corresponding bulk materials, including fcc Al, fcc Ti, hcp Al, and hcp Ti.more » In all cases, the calculated Ed in the multilayers are intermediate to the corresponding bulk values but exhibit some important directionality. In the nanolayer, defect detection demonstrated systematic differences in the behavior of Ed in each layer. Importantly, collision cascade damage exhibits significant defect partitioning within the Al and Ti layers that is hypothesized to be an intrinsic property of dissimilar nanolayered systems. This type of partitioning could be partly responsible for observed asymmetric radiation damage responses in many multilayered systems. In addition, a pseudo-random direction was introduced to approximate the average Ed without performing numerous simulations with random directions.« less
Microscope collision protection apparatus
DeNure, Charles R.
2001-10-23
A microscope collision protection apparatus for a remote control microscope which protects the optical and associated components from damage in the event of an uncontrolled collision with a specimen, regardless of the specimen size or shape. In a preferred embodiment, the apparatus includes a counterbalanced slide for mounting the microscope's optical components. This slide replaces the rigid mounts on conventional upright microscopes with a precision ball bearing slide. As the specimen contacts an optical component, the contacting force will move the slide and the optical components mounted thereon. This movement will protect the optical and associated components from damage as the movement causes a limit switch to be actuated, thereby stopping all motors responsible for the collision.
Comparison of heavy-ion transport simulations: Collision integral in a box
NASA Astrophysics Data System (ADS)
Zhang, Ying-Xun; Wang, Yong-Jia; Colonna, Maria; Danielewicz, Pawel; Ono, Akira; Tsang, Manyee Betty; Wolter, Hermann; Xu, Jun; Chen, Lie-Wen; Cozma, Dan; Feng, Zhao-Qing; Das Gupta, Subal; Ikeno, Natsumi; Ko, Che-Ming; Li, Bao-An; Li, Qing-Feng; Li, Zhu-Xia; Mallik, Swagata; Nara, Yasushi; Ogawa, Tatsuhiko; Ohnishi, Akira; Oliinychenko, Dmytro; Papa, Massimo; Petersen, Hannah; Su, Jun; Song, Taesoo; Weil, Janus; Wang, Ning; Zhang, Feng-Shou; Zhang, Zhen
2018-03-01
Simulations by transport codes are indispensable to extract valuable physical information from heavy-ion collisions. In order to understand the origins of discrepancies among different widely used transport codes, we compare 15 such codes under controlled conditions of a system confined to a box with periodic boundary, initialized with Fermi-Dirac distributions at saturation density and temperatures of either 0 or 5 MeV. In such calculations, one is able to check separately the different ingredients of a transport code. In this second publication of the code evaluation project, we only consider the two-body collision term; i.e., we perform cascade calculations. When the Pauli blocking is artificially suppressed, the collision rates are found to be consistent for most codes (to within 1 % or better) with analytical results, or completely controlled results of a basic cascade code. In orderto reach that goal, it was necessary to eliminate correlations within the same pair of colliding particles that can be present depending on the adopted collision prescription. In calculations with active Pauli blocking, the blocking probability was found to deviate from the expected reference values. The reason is found in substantial phase-space fluctuations and smearing tied to numerical algorithms and model assumptions in the representation of phase space. This results in the reduction of the blocking probability in most transport codes, so that the simulated system gradually evolves away from the Fermi-Dirac toward a Boltzmann distribution. Since the numerical fluctuations are weaker in the Boltzmann-Uehling-Uhlenbeck codes, the Fermi-Dirac statistics is maintained there for a longer time than in the quantum molecular dynamics codes. As a result of this investigation, we are able to make judgements about the most effective strategies in transport simulations for determining the collision probabilities and the Pauli blocking. Investigation in a similar vein of other ingredients in transport calculations, like the mean-field propagation or the production of nucleon resonances and mesons, will be discussed in the future publications.
Mechanisms of cell damage in agitated microcarrier tissue culture reactors
NASA Technical Reports Server (NTRS)
Cherry, Robert S.; Papoutsakis, E. Terry
1986-01-01
Cells growing on microcarriers may be damaged by collisions of the microcarrier against another microcarrier or the reactor agitator. Bead-bead collisions are caused by small-scale turbulence, which can also cause high local shear stress on the cells. The cells are also exposed to 10-20 Hz cyclic shear stress by bead rotation.
Three-dimensional particle-in-cell simulation on gain saturation effect of microchannel plate
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Qiangqiang; Yuan, Zheng; Cao, Zhurong, E-mail: cao33jin@aliyun.com
We present here the results of the simulation work, using the three-dimensional particle-in-cell method, on the performance of the lead glass microchannel plate under saturated state. We calculated the electron cascade process with different DC bias voltages under both self-consistent condition and non-self-consistent condition. The comparative results have demonstrated that the strong self-consistent field can suppress the cascade process and make the microchannel plate saturated. The simulation results were also compared to the experimental data and good agreement was obtained. The simulation results also show that the electron multiplication process in the channel is accompanied by the buildup process ofmore » positive charges in the channel wall. Though the interactions among the secondary electron cloud in the channel, the positive charges in the channel wall, and the external acceleration field can make the electron-surface collision more frequent, the collision energy will be inevitably reduced, thus the electron gain will also be reduced.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Geiger, K.; Longacre, R.; Srivastava, D.K.
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 inmore » 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.« less
OBJECT KINETIC MONTE CARLO SIMULATIONS OF CASCADE ANNEALING IN TUNGSTEN
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.
2014-03-31
The objective of this work is to study the annealing of primary cascade damage created by primary knock-on atoms (PKAs) of various energies, at various temperatures in bulk tungsten using the object kinetic Monte Carlo (OKMC) method.
Development of FB-MultiPier dynamic vessel-collision analysis models, phase 2 : [summary].
DOT National Transportation Integrated Search
2014-07-01
When collisions between large vessels and bridge : supports occur, they can result in significant : damage to bridge and vessel. These collisions : are extremely hazardous, often taking lives on : the vessel and the bridge. Direct costs of repair : a...
Energy transfer, pressure tensor, and heating of kinetic plasma
NASA Astrophysics Data System (ADS)
Yang, Yan; Matthaeus, William H.; Parashar, Tulasi N.; Haggerty, Colby C.; Roytershteyn, Vadim; Daughton, William; Wan, Minping; Shi, Yipeng; Chen, Shiyi
2017-07-01
Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade, and convert kinetic energy into heat are hotly debated. Here, we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spatial filtering on the Vlasov equation, we extract information at prescribed scales and introduce several energy transfer functions. This approach allows highly inhomogeneous energy cascade to be quantified as it proceeds down to kinetic scales. The pressure work, - ( P . ∇ ) . u , can trigger a channel of the energy conversion between fluid flow and random motions, which contains a collision-free generalization of the viscous dissipation in collisional fluid. Both the energy transfer and the pressure work are strongly correlated with velocity gradients.
Collision-spike sputtering of Au nanoparticles
Sandoval, Luis; Urbassek, Herbert M.
2015-08-06
Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; themore » remainder is transported away by the transmitted projectile and the ejecta. As a result, the sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.« less
A study and comparison of the effects of low speed change vehicle collisions on the human body.
Hoyes, Philip; Henderson, Brian
2013-03-01
In motor vehicle collisions there is a well-established relationship between the level of damage sustained by the vehicle, its change in speed during the collision period, the movement of occupants and the potential for their injury. Greater damage, with respect to structure, means a greater potential for injury. In terms of rear-end impacts, speed change thresholds for injury have been suggested in previous literature. This research uses human test subjects and three full-scale vehicle, rear-end collisions to investigate the correlation between speed change and occupant movement and uses it to test the suggestion of a second threshold where the accelerations are similar to an everyday activity. Copyright © 2012 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Farnan, I.; Trachenko, K.
2003-04-01
29Si nuclear magnetic resonance (NMR) is a one of the most useful probes of the local structure of silicates. One of the results of recent studies of naturally radiation damaged zircons is that there is an evolution of the local structure in both crystalline and amorphous fractions of partially metamict zircon as a function of accumulated α-dose. We have examined the evolution of this local structure within the framework of several models of damage accumulation. The total number of displaced atoms produced per α-decay as function of accumulated dose, as measured by NMR, is not consistent with the idea of multiple overlap events being responsible for the evolution of the total damaged fraction. However, increased connectivity in the damaged region as the number of α-events increases is correlated to the degree of cascade overlap. The results of large scale atomistic (MD) simulations of heavy nuclei recoils at realistic energies (70keV) are consistent with the NMR quantification and also with TEM estimates of the diameters of damaged regions. The local heterogeneity (density and bonding) in the damaged area in the simulations is consistent with the existence of connected silicate tetrahedra. Detailed experiments on the annealing of damaged zircons at 500 and 600^oC have been performed. These show that a significant energetic barrier to the recrystallisation exists at these temperatures once a small fraction of damaged material has been recrystallised. This correlates well with the degree of cascade overlap. Indicating that the more connected SiO_4 tetrahedra present this barrier. A sample with very little cascade overlap can be annealed to ˜97% crystallinity at these temperatures.
RNF168 forms a functional complex with RAD6 during the DNA damage response
Liu, Chao; Wang, Degui; Wu, Jiaxue; Keller, Jennifer; Ma, Teng; Yu, Xiaochun
2013-01-01
Summary Protein ubiquitination plays an important role in initiating the DNA damage response. Following DNA damage, E2 ubiquitin conjugating enzymes are crucial for catalyzing substrate ubiquitination that recruits downstream DNA repair factors to DNA lesions. To identify novel E2 conjugating enzymes important for initiating the DNA-damage-induced ubiquitination cascade, we screened most of the known E2 enzymes and found that RAD6A and RAD6B function together with RNF168 in the ionizing radiation (IR)-induced DNA damage response. Similarly to RNF168-deficient cells, RAD6A- or RAD6B-deficient cells exhibit a reduction in DNA-damage-induced protein ubiquitination. Correspondingly, DNA-damage-induced foci formation of DNA damage repair proteins, such as BRCA1 and 53BP1, is impaired in the absence of RAD6A or RAD6B. Moreover, the RNF168–RAD6 complex targeted histone H1.2 for ubiquitination in vitro and regulated DNA-damage-induced histone H1.2 ubiquitination in vivo. Collectively, these data demonstrate that RNF168, in complex with RAD6A or RAD6B, is activated in the DNA-damage-induced protein ubiquitination cascade. PMID:23525009
Lu, Chenyang; Jin, Ke; Béland, Laurent K.; ...
2016-02-01
We report that energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters farmore » exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance.« less
Solar System Evolution through Planetesmial Collisions
NASA Astrophysics Data System (ADS)
Trierweiler, Isabella; Laughlin, Greg
2018-01-01
Understanding planet formation is crucial to unraveling the history of our Solar System. Refining our theory of planet formation has become particularly important as the discovery of exoplanet systems through missions like Kepler have indicated that our system is incredibly unique. Compared to other systems around Sun-like stars, we are missing a significant amount of mass in the inner region of our solar system.A leading explanation for the low mass of the terrestrial planets is Jupiter’s Grand Tack. In this theory, the existence of the rocky planets is thought to be the result of the migration of Jupiter through the inner solar system. This migration could spark a collisional cascade of planetesimals, allowing planetesimals to drift inwards and shepherd an original set of massive planets into the Sun, thus explaining the absence of massive planets in our current system. The remnants of the planetesimals would them become the building blocks for a new generation of smaller, rocky planets.Using the N-body simulator REBOUND, we investigate the dynamics of the Grand Tack. We focus in particular on collisional cascades, which are thought to cause the inward planetesimal drift. We first modify the simulator to account for fragmentation outcomes in planetesimal collisions. Modeling disks of varying initial conditions, we then characterize the disk conditions needed to begin a cascade and shed light on the solar system’s dynamics just prior to the formation of the terrestrial planets.
MOLECULAR DYNAMICS OF CASCADES OVERLAP IN TUNGSTEN WITH 20-KEV PRIMARY KNOCK-ON ATOMS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.
2015-04-16
Molecular dynamics simulations are performed to investigate the mutual influence of two subsequent cascades in tungsten. The influence is studied using 20-keV primary knock-on atoms, to induce one cascade after another separated by 15 ps, in a lattice temperature of 1025 K (i.e. 0.25 of the melting temperature of the interatomic potential). The center of mass of the vacancies at the peak damage during the cascade is taken as the location of the cascade. The distance between this location to that of the next cascade is taken as the overlap parameter. Empirical fits describing the number of surviving vacancies andmore » interstitial atoms as a function of overlap are presented.« less
Self-similar inverse cascade of magnetic helicity driven by the chiral anomaly
Hirono, Yuji; Kharzeev, Dmitri E.; Yin, Yi
2015-12-28
For systems with charged chiral fermions, the imbalance of chirality in the presence of magnetic field generates an electric current—this is the chiral magnetic effect (CME). We study the dynamical real-time evolution of electromagnetic fields coupled by the anomaly to the chiral charge density and the CME current by solving the Maxwell-Chern-Simons equations. We find that the CME induces the inverse cascade of magnetic helicity toward the large distances, and that at late times this cascade becomes self-similar, with universal exponents. We also find that in terms of gauge field topology the inverse cascade represents the transition from linked electricmore » and magnetic fields (Hopfions) to the knotted configuration of magnetic field (Chandrasekhar-Kendall states). The magnetic reconnections are accompanied by the pulses of the CME current directed along the magnetic field lines. In conclusion, we devise an experimental signature of these phenomena in heavy ion collisions, and speculate about implications for condensed matter systems.« less
Damage Evaluation of Concrete Column under Impact Load Using a Piezoelectric-Based EMI Technique.
Fan, Shuli; Zhao, Shaoyu; Qi, Baoxin; Kong, Qingzhao
2018-05-17
One of the major causes of damage to column-supported concrete structures, such as bridges and highways, are collisions from moving vehicles, such as cars and ships. It is essential to quantify the collision damage of the column so that appropriate actions can be taken to prevent catastrophic events. A widely used method to assess structural damage is through the root-mean-square deviation (RMSD) damage index established by the collected data; however, the RMSD index does not truly provide quantitative information about the structure. Conversely, the damage volume ratio that can only be obtained via simulation provides better detail about the level of damage in a structure. Furthermore, as simulation can also provide the RMSD index relating to that particular damage volume ratio, the empirically obtained RMSD index can thus be related to the structural damage degree through comparison of the empirically obtained RMSD index to numerically-obtained RMSD. Thus, this paper presents a novel method in which the impact-induced damage to a structure is simulated in order to obtain the relationship between the damage volume ratio to the RMSD index, and the relationship can be used to predict the true damage degree by comparison to the empirical RMSD index. In this paper, the collision damage of a bridge column by moving vehicles was simulated by using a concrete beam model subjected to continuous impact loadings by a freefalling steel ball. The variation in admittance signals measured by the surface attached lead zirconate titanate (PZT) patches was used to establish the RMSD index. The results demonstrate that the RMSD index and the damage ratio of concrete have a linear relationship for the particular simulation model.
Nuclear collective flow and charged-pion emission in Ne-nucleus collisions at E/A = 800 MeV
NASA Technical Reports Server (NTRS)
Gosset, J.; Valette, O.; Babinet, R.; Alard, J. P.; Augerat, J.
1989-01-01
Triple-differential cross sections of charged pions were measured for collisions of Ne projectiles at E/A = 800 MeV with NaF, Nb, and Pb targets. The reaction plane was estimated event by event from the light-baryon momentum distribution. For heavy targets, preferential emission of charged pions away from the interaction zone toward the projectile side was observed in the transverse direction. Such a preferential emission, which is not predicted by cascade calculations, may be attributed to a stronger pion absorption by the heavier spectator remnant.
Nuclear collective flow and charged-pion emission in Ne-nucleus collisions at E/A = 800 MeV
NASA Technical Reports Server (NTRS)
Gosset, J.; Valette, O.; Alard, J. P.; Augerat, J.; Babinet, R.; Bastid, N.; Brochard, F.; De Marco, N.; Dupieux, P.; Fodor, Z.;
1989-01-01
Triple-differential cross sections of charged pions were measured for collisions of Ne projectiles at E/A = 800 MeV with NaF, Nb, and Pb targets. The reaction plane was estimated event by event from the light-baryon momentum distribution. For heavy targets, preferential emission of charged pions away from the interaction zone towards the projectile side was observed in the transverse direction. Such a preferential emission, which is not predicted by cascade calculations, may be attributed to a stronger pion absorption by the heavier spectator remnant.
USDA-ARS?s Scientific Manuscript database
Corneal abrasion not only damages the epithelium but also induces stromal keratocyte death at the site of injury. While a coordinated cascade of inflammatory cell recruitment facilitates epithelial restoration, it is unclear if this cascade is necessary for keratocyte recovery. Since platelet and ne...
DOE Office of Scientific and Technical Information (OSTI.GOV)
Xue, Haizhou; Zhang, Yanwen; Weber, William J.
Understanding how energy deposited in electronic and atomic subsystems may affect defect dynamics is a long-standing fundamental challenge in materials research. The coupling of displacement cascades and in-cascade ionization-induced annealing are investigated in silicon carbide (SiC). A delayed damage accumulation under ion irradiation is revealed with a linear dependence as a function of both increasing ionization and increasing ratio of electronic to nuclear energy deposition. An in-cascade healing mechanism is suggested with a low threshold value of electronic energy loss (~1.0 keV nm-1). The in-cascade ionization effects must be considered in predicting radiation performance of SiC.
Shear and mixing effects on cells in agitated microcarrier tissue culture reactors
NASA Technical Reports Server (NTRS)
Cherry, Robert S.; Papoutsakis, E. Terry
1987-01-01
Tissue cells are known to be sensitive to mechanical stresses imposed on them by agitation in bioreactors. The amount of agitation provided in a microcarrier or suspension bioreactor should be only enough to provide effective homogeneity. Three distinct flow regions can be identified in the reactor: bulk turbulent flow, bulk laminar flow and boundary-layer flows. Possible mechanisms of cell damage are examined by analyzing the motion of microcarriers or free cells relative to the surrounding fluid, to each other and to moving or stationary solid surfaces. The primary mechanisms of cell damage appear to result from: (1) direct interaction between microcarriers and turbulent eddies; (2) collisions between microcarriers in turbulent flow; and (3) collisions against the impeller or other stationary surfaces. If the smallest eddies of turbulent flow are of the same size as the microcarrier beads, they may cause high shear stresses on the cells. Eddies the size of the average interbead spacing may cause bead-bead collisions which damage cells. The severity of the collisions increases when the eddies are also of the same size as the beads. Impeller collisions occur when beads cannot avoid the impeller leading edge as it advances through the liquid. The implications of the results of this analysis on the design and operation of tissue culture reactors are discussed.
NASA Astrophysics Data System (ADS)
Batyuk, P.; Karpenko, Iu.; Lednicky, R.; Malinina, L.; Mikhaylov, K.; Rogachevsky, O.; Wielanek, D.
2017-08-01
Correlation femtoscopy allows one to measure the space-time characteristics of particle production in relativistic heavy-ion collisions due to the effects of quantum statistics (QS) and final state interactions (FSIs). The main features of the femtoscopy measurements at top RHIC and LHC energies are considered as a manifestation of strong collective flow and are well interpreted within hydrodynamic models employing equation of state (EoS) with a crossover type transition between quark-gluon plasma (QGP) and hadron gas phases. The femtoscopy at lower energies was intensively studied at AGS and SPS accelerators and is being studied now in the Beam Energy Scan program (BES) at the BNL Relativistic Heavy Ion Collider in the context of exploration of the QCD phase diagram. In this article we present femtoscopic observables calculated for Au-Au collisions at √{sN N}=7.7 -62.4 GeV in a viscous hydro + cascade model vHLLE+UrQMD and their dependence on the EoS of thermalized matter.
NASA Astrophysics Data System (ADS)
1981-01-01
Test vehicles were instrumented with accelerometers to measure vehicle accelerator resultants. The vehicles were also identified for residual crush and collision deformation classification (CDC) measurements.
Road collision facts Ireland, 2004
DOT National Transportation Integrated Search
2005-11-01
This report covers all road traffic collisions reported to : the Garda Sochna, where details were recorded and : forwarded to the National Roads Authority, involving : fatalities, personal injury or material damage which : occurred on public road...
Road collision facts Ireland, 2003
DOT National Transportation Integrated Search
2005-02-01
This report covers all road traffic collisions reported to : the Garda Sochna, where details were recorded and : forwarded to the National Roads Authority, involving : fatalities, personal injury or material damage which : occurred on public road...
Irradiation creep due to SIPA under cascade damage conditions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Woo, C.H.; Garner, F.A.; Holt, R.A.
1992-12-31
This paper derives the relationships between void swelling and irradiation creep due to Stress-Induced Preferred Absorption (SIPA) and SIPA-Induced Growth (SIG) under cascade damage conditions in an irradiated pressurized tube. It is found that at low swelling rates irradiation creep is a major contribution to the total diametral strain rate of the tube, whereas at high swelling rates the creep becomes a minor contribution. The anisotropy of the corresponding dislocation structure is also predicted to decline as the swelling rate increases. The theoretical predictions are found to agree very well with experimental results.
Intermolecular Coulombic Decay (ICD) Occuring in Triatomic Molecular Dimer
NASA Astrophysics Data System (ADS)
Iskandar, Wael; Gatton, Averell; Gaire, Bishwanath; Champenois, Elio; Larsen, Kirk; Shivaram, Niranjan; Moradmand, Ali; Severt, Travis; Williams, Joshua; Slaughter, Daniel; Weber, Thorsten
2017-04-01
For over two decades, the production of ICD process has been extensively investigated theoretically and experimentally in different systems bounded by a week force (ex. van-der-Waals or Hydrogen force). Furthermore, the ICD process has been demonstrated a strong implication in biological system (DNA damage and DNA repair mechanism) because of the production of genotoxic low energy electrons during the decay cascade. Studying large complex system such as triatomic molecular dimer may be helpful for further exploration of ``Auger electron driven cancer therapy''. The present experiment investigates the dissociation dynamics happened in collision between a photons and CO2 dimer. We will focus more specifically on the CO2++CO2+ fragmentation channel and the detection in coincidence of the two ionic fragments and the two electrons will be done using a COld Target Recoil Ion Momentum Spectroscopy (COLTRIMS). The measurements of the Kinetic Energy Release of the two fragments and the relative angular distribution of the electrons in the molecular frame reveal that the ICD is the only mechanism responsible for the production of this fragmentation channel.
Optimization of Automobile Crush Characteristics: Technical Report
DOT National Transportation Integrated Search
1975-10-01
A methodology is developed for the evaluation and optimization of societal costs of two-vehicle automobile collisions. Costs considered in a Figure of Merit include costs of injury/mortality, occupant compartment penetration, collision damage repairs...
Medium-Induced QCD Cascade: Democratic Branching and Wave Turbulence
NASA Astrophysics Data System (ADS)
Blaizot, J.-P.; Iancu, E.; Mehtar-Tani, Y.
2013-08-01
We study the average properties of the gluon cascade generated by an energetic parton propagating through a quark-gluon plasma. We focus on the soft, medium-induced emissions which control the energy transport at large angles with respect to the leading parton. We show that the effect of multiple branchings is important. In contrast with what happens in a usual QCD cascade in vacuum, medium-induced branchings are quasidemocratic, with offspring gluons carrying sizable fractions of the energy of their parent gluon. This results in an efficient mechanism for the transport of energy toward the medium, which is akin to wave turbulence with a scaling spectrum ˜1/ω. We argue that the turbulent flow may be responsible for the excess energy carried by very soft quanta, as revealed by the analysis of the dijet asymmetry observed in Pb-Pb collisions at the LHC.
Effect of multiparticle collisions on pion production in relativistic heavy-ion reactions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Goncalves, M.G.; Medeiros, E.L.; Duarte, S.B.
In the present work we discuss the effect of N-body processes on pion multiplicity in relativistic heavy-ion reactions. This effect is analyzed in the energy range from the pion threshold up to 2 GeV/nucleon, for several projectile-target systems. The analysis is carried out in the context of intranuclear cascade calculations. It is shown that the inclusion of multibaryonic collisions is a crucial element in the study of the pion production mechanisms, being strongly dependent on the adopted correlation range for the particles involved in the N-body processes. {copyright} {ital 1997} {ital The American Physical Society}
NASA Astrophysics Data System (ADS)
Bury, Marcin; Van Haevermaet, Hans; Van Hameren, Andreas; Van Mechelen, Pierre; Kutak, Krzysztof; Serino, Mirko
2018-05-01
We present calculations of single inclusive jet transverse momentum and energy spectra at forward rapidity (5.2 < y < 6.6) in proton-lead collisions with √{sNN } = 5.02 TeV. The predictions are obtained with the KaTie Monte Carlo event generator, which allows to calculate interactions within the High Energy Factorisation framework. The tree-level matrix element results are subsequently interfaced with the CASCADE Monte Carlo event generator to account for hadronisation. The effects of the saturation of the gluon density, leading to suppression of the cross section, are investigated.
The extension of the INCL model for simulation of shielding in space
NASA Astrophysics Data System (ADS)
Pedoux, Sophie; Cugnon, Joseph; Mancusi, Davide; Boudard, Alain; David, Jean-Christophe; Leray, Sylvie
The energy spectrum of protons in cosmic rays has its maximum flux around 1 GeV but remains important for energies up to 20 GeV. Space radiation is also composed of helium nuclei (around 10(¡1damage in material and tissue. It has been shown that the Li`ge Intranuclear Cascade model (INCL), which will be briefly in-e troduced, reproduces fairly well a great deal of experimental data for nucleon-induced reactions in the 200 MeV to 2 GeV range [1], when coupled with the ABLA evaporation-fission code developed by K.-H. Schmidt [2]. It should be stressed that this agreement is achieved without adjustment of parameters in the INCL part. We will present three extensions of INCL4 that have been investigated in order to make the model useful for the study of space radiation transport. First, we will introduce its extension to nucleon-nucleus reactions at energies up to 15 GeV, which has been realized by including additional pion-production channels in collisions during the cascade. Second, we will describe the newly implemented coalescence mechanism for the emission of light charged particle and, finally, we will discuss how light ions can be accommodated as projectiles in INCL4. We will show some results and compare them with relevant experimental data. Implication for space radio-protection issues will be discussed. [1] A. Boudard, J. Cugnon, S. Leray and C. Volant, Phys. Rev. C66 (2002)044615 [2] J.-J. Gaimard and K.-H. Schmidt, Nucl. Phys. A531(1991)
Cumulative Damage in Strength-Dominated Collisions of Rocky Asteroids: Rubble Piles and Brick Piles
NASA Technical Reports Server (NTRS)
Housen, Kevin
2009-01-01
Laboratory impact experiments were performed to investigate the conditions that produce large-scale damage in rock targets. Aluminum cylinders (6.3 mm diameter) impacted basalt cylinders (69 mm diameter) at speeds ranging from 0.7 to 2.0 km/s. Diagnostics included measurements of the largest fragment mass, velocities of the largest remnant and large fragments ejected from the periphery of the target, and X-ray computed tomography imaging to inspect some of the impacted targets for internal damage. Significant damage to the target occurred when the kinetic energy per unit target mass exceeded roughly 1/4 of the energy required for catastrophic shattering (where the target is reduced to one-half its original mass). Scaling laws based on a rate-dependent strength were developed that provide a basis for extrapolating the results to larger strength-dominated collisions. The threshold specific energy for widespread damage was found to scale with event size in the same manner as that for catastrophic shattering. Therefore, the factor of four difference between the two thresholds observed in the lab also applies to larger collisions. The scaling laws showed that for a sequence of collisions that are similar in that they produce the same ratio of largest fragment mass to original target mass, the fragment velocities decrease with increasing event size. As a result, rocky asteroids a couple hundred meters in diameter should retain their large ejecta fragments in a jumbled rubble-pile state. For somewhat larger bodies, the ejection velocities are sufficiently low that large fragments are essentially retained in place, possibly forming ordered "brick-pile" structures.
Sputtering Erosion in the Ion Thruster
NASA Technical Reports Server (NTRS)
Ray, Pradosh K.; Mantenieks, Maris A. (Technical Monitor)
2000-01-01
During the first phase of this research, the sputtering yields of molybdenum by low energy (100 eV and higher) xenon ions were measured by using the methods of secondary neutral mass spectrometry (SNMS) and Rutherford backscattering spectrometry (RBS). However, the measured sputtering yields were found to be far too low to explain the sputtering erosions observed in the long-duration tests of ion thrusters. The only difference between the sputtering yield measurement experiments and the ion thruster tests was that the later are conducted at high ion fluences. Hence, a study was initiated to investigate if any linkage exists between high ion fluence and an enhanced sputtering yield. The objective of this research is to gain an understanding of the causes of the discrepancies between the sputtering rates of molybdenum grids in an ion thruster and those measured from our experiments. We are developing a molecular dynamics simulation technique for studying low-energy xenon ion interactions with molybdenum. It is difficult to determine collision sequences analytically for primary ions below the 200 eV energy range where the ion energy is too low to be able to employ a random cascade model with confidence and it is too high to have to consider only single collision at or near the surface. At these low energies, the range of primary ions is about 1 to 2 nm from the surface and it takes less than 4 collisions on the average to get an ion to degrade to such an energy that it can no longer migrate. The fine details of atomic motion during the sputtering process are revealed through computer simulation schemes. By using an appropriate interatomic potential, the positions and velocities of the incident ion together with a sufficient number of target atoms are determined in small time steps. Hence, it allows one to study the evolution of damages in the target and its effect on the sputtering yield. We are at the preliminary stages of setting up the simulation program.
2011-03-22
Aircraft collisions with birds and other wildlife annually cause millions of dollars in aircraft damage and may result in loss of life and aircraft...collisions with birds and other wildlife annually cause millions of dollars in aircraft damage and may result in loss of life and aircraft. More...Action would support the BASH program and meet the AF goal of reducing the loss of life and of valuable aircraft and other resources. Figure 1-2
Estimating the harms and costs of cannabis-attributable collisions in the Canadian provinces.
Wettlaufer, Ashley; Florica, Roxana O; Asbridge, Mark; Beirness, Douglas; Brubacher, Jeffrey; Callaghan, Russell; Fischer, Benedikt; Gmel, Gerrit; Imtiaz, Sameer; Mann, Robert E; McKiernan, Anna; Rehm, Jürgen
2017-04-01
In 2012, 10% of Canadians used cannabis and just under half of those who use cannabis were estimated to have driven under the influence of cannabis. Substantial evidence has accumulated to indicate that driving after cannabis use increases collision risk significantly; however, little is known about the extent and costs associated with cannabis-related traffic collisions. This study quantifies the costs of cannabis-related traffic collisions in the Canadian provinces. Province and age specific cannabis-attributable fractions (CAFs) were calculated for traffic collisions of varying severity. The CAFs were applied to traffic collision data in order to estimate the total number of persons involved in cannabis-attributable fatal, injury and property damage only collisions. Social cost values, based on willingness-to-pay and direct costs, were applied to estimate the costs associated with cannabis-related traffic collisions. The 95% confidence intervals were calculated using Monte Carlo methodology. Cannabis-attributable traffic collisions were estimated to have caused 75 deaths (95% CI: 0-213), 4407 injuries (95% CI: 20-11,549) and 7794 people (95% CI: 3107-13,086) were involved in property damage only collisions in Canada in 2012, totalling $1,094,972,062 (95% CI: 37,069,392-2,934,108,175) with costs being highest among younger people. The cannabis-attributable driving harms and costs are substantial. The harm and cost of cannabis-related collisions is an important factor to consider as Canada looks to legalize and regulate the sale of cannabis. This analysis provides evidence to help inform Canadian policy to reduce the human and economic costs of drug-impaired driving. Copyright © 2017 Canadian Centre on Substance Abuse. Published by Elsevier B.V. All rights reserved.
33 CFR 70.05-15 - Liability for damages.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Liability for damages. 70.05-15 Section 70.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation...
33 CFR 70.05-15 - Liability for damages.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Liability for damages. 70.05-15 Section 70.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation...
33 CFR 70.05-15 - Liability for damages.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Liability for damages. 70.05-15 Section 70.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation...
33 CFR 70.05-15 - Liability for damages.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Liability for damages. 70.05-15 Section 70.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation...
33 CFR 70.05-15 - Liability for damages.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Liability for damages. 70.05-15 Section 70.05-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation...
An overheight vehicle bridge collision monitoring system using piezoelectric transducers
NASA Astrophysics Data System (ADS)
Song, G.; Olmi, C.; Gu, H.
2007-04-01
With increasing traffic volume follows an increase in the number of overheight truck collisions with highway bridges. The detection of collision impact and evaluation of the impact level is a critical issue in the maintenance of a concrete bridge. In this paper, an overheight collision detection and evaluation system is developed for concrete bridge girders using piezoelectric transducers. An electric circuit is designed to detect the impact and to activate a digital camera to take photos of the offending truck. Impact tests and a health monitoring test were conducted on a model concrete bridge girder by using three piezoelectric transducers embedded before casting. From the experimental data of the impact test, it can be seen that there is a linear relation between the output of sensor energy and the impact energy. The health monitoring results show that the proposed damage index indicates the level of damage inside the model concrete bridge girder. The proposed overheight truck-bridge collision detection and evaluation system has the potential to be applied to the safety monitoring of highway bridges.
Rogue wave generation by inelastic quasi-soliton collisions in optical fibres
NASA Astrophysics Data System (ADS)
Eberhard, M.; Savojardo, A.; Maruta, A.; Römer, R. A.
2017-11-01
We demonstrate a simple cascade mechanism that drives the formation and emergence of rogue waves in the generalized non-linear Schr\\"{o}dinger equation with third-order dispersion. This conceptually novel generation mechanism is based on inelastic collisions of quasi-solitons and is well described by a resonant-like scattering behaviour for the energy transfer in pair-wise quasi-soliton collisions. Our results demonstrate a threshold for rogue wave emergence and the existence of a period of reduced amplitudes - a "calm before the storm" - preceding the arrival of a rogue wave event. Comparing with ultra-long time window simulations of $3.865\\times 10^{6}$ps we observe the statistics of rogue waves in optical fibres with an unprecedented level of detail and accuracy, unambiguously establishing the long-ranged character of the rogue wave power-distribution function over seven orders of magnitude.
Radiation response of nanotwinned Cu under multiple-collision cascades
NASA Astrophysics Data System (ADS)
Wu, Lianping; Yu, Wenshan; Hu, Shuling; Shen, Shengping
2018-07-01
In this paper, multiple collision cascades (MCC) of nanotwinned (nt) Cu with three different twin spacings are performed to model the response of nt Cu upon a radiation dose of 1 displacements per atom (dpa). Considering the defects developed with high randomness in the material during a MCC process, each MCC in a nt Cu is conducted for eight times. This enables us to analyze some average properties of defect clusters in the radiated nt Cu with different twin spacings at the different radiation doses. We also analyze the microstructural evolution in the nt Cu during the MCC. Smaller size of defect clusters and lower defect density are seen in the nt Cu with smaller twin spacing. In addition, a number of defect clusters could be removed via their frequent interactions with the coherent twin boundaries (CTBs) during the MCC. This induces either the migration of CTBs or the healing of CTBs. Moreover, the potential formation and elimination mechanisms of stacking fault are found to be due to the climb of Frank partial dislocation and glide of Shockley partial dislocations. This study provides further evidence on the irradiation tolerance of CTBs and the self-healing capability of CTBs in response to radiation.
Feeding supermassive black holes by collisional cascades
NASA Astrophysics Data System (ADS)
Faber, Christian; Dehnen, Walter
2018-05-01
The processes driving gas accretion on to supermassive black holes (SMBHs) are still poorly understood. Angular momentum conservation prevents gas within ˜10 pc of the black hole from reaching radii ˜10-3 pc where viscous accretion becomes efficient. Here we present simulations of the collapse of a clumpy shell of swept-up isothermal gas, which is assumed to have formed as a result of feedback from a previous episode of AGN activity. The gas falls towards the SMBH forming clumps and streams, which intersect, collide, and often form a disc. These collisions promote partial cancellations of angular momenta, resulting in further infall and more collisions. This continued collisional cascade generates a tail of gas with sufficiently small angular momenta and provides a viable route for gas inflow to sub-parsec scales. The efficiency of this process hardly depends on details, such as gas temperature, initial virial ratio and power spectrum of the gas distribution, as long as it is not strongly rotating. Adding star formation to this picture might explain the near-simultaneous formation of the S-stars (from tidally disrupted binaries formed in plunging gas streams) and the sub-parsec young stellar disc around Sgr A⋆.
Feeding supermassive black holes by collisional cascades
NASA Astrophysics Data System (ADS)
Faber, Christian; Dehnen, Walter
2018-07-01
The processes driving gas accretion on to supermassive black holes (SMBHs) are still poorly understood. Angular momentum conservation prevents gas within ˜10 pc of the black hole from reaching radii ˜10-3pc where viscous accretion becomes efficient. Here we present simulations of the collapse of a clumpy shell of swept-up isothermal gas, which is assumed to have formed as a result of feedback from a previous episode of AGN activity. The gas falls towards the SMBH forming clumps and streams, which intersect, collide and often form a disc. These collisions promote partial cancellations of angular momenta, resulting in further infall and more collisions. This continued collisional cascade generates a tail of gas with sufficiently small angular momenta and provides a viable route for gas inflow to sub-parsec scales. The efficiency of this process hardly depends on details, such as gas temperature, initial virial ratio and power spectrum of the gas distribution, as long as it is not strongly rotating. Adding star formation to this picture might explain the near-simultaneous formation of the S-stars (from tidally disrupted binaries formed in plunging gas streams) and the sub-parsec young stellar disc around Sgr A⋆.
Chirped quantum cascade laser induced rapid passage signatures in an optically thick gas
NASA Astrophysics Data System (ADS)
Northern, J. H.; Ritchie, G. A. D.; Smakman, E. P.; van Helden, J. H.; Walker, R. J.; Duxbury, G.
2011-01-01
We report observations of rapid passage signals induced in samples of N2O and CH4 present in a multipass cell with an optical path length of 5 m. The effect of laser power and chirp rate upon the signals has been studied by utilising two different chirped quantum cascade lasers operating around 8 μm. The rapid passage signals exhibit an increasing delay in the switch from absorption to emission as a function of increased gas pressure (up to 8 Torr of gas). By comparing a selection of transitions in N2O and CH4, we show that, unlike ammonia, this `pressure shift' is independent of the transition dipole moment, spectroscopic branch probed and laser chirp rate. As the transition dipole moment is much larger in nitrous oxide than methane, we believe that this indicates that N2O-N2O collisions are more efficient at removing coherence from the polarised sample than CH4-CH4 collisions. We have also observed this pressure shift in a short path length of 40 cm, although with a much reduced value, indicating that propagation effects are important in this optically thick minimally damped system.
A novel method for computing effective diffusivity: Application to helium implanted α-Fe thin films
NASA Astrophysics Data System (ADS)
Dunn, Aaron; Agudo-Merida, Laura; Martin-Bragado, Ignacio; McPhie, Mathieu; Cherkaoui, Mohammed; Capolungo, Laurent
2014-05-01
The effective diffusivity of helium in thin iron films is quantified using spatially resolved stochastic cluster dynamics and object kinetic Monte Carlo simulations. The roles of total displacement dose (in DPA), damage rate, helium to DPA ratio, layer thickness, and damage type (cascade damage vs Frenkel pair implantation) on effective He diffusivity are investigated. Helium diffusivity is found to decrease with increasing total damage and decreasing damage rate. Arrhenius plots show strongly increased helium diffusivity at high temperatures, high total implantation, and low implantation rates due to decreased vacancy and vacancy cluster concentrations. At low temperatures, effective diffusivity is weakly dependent on foil thickness while at high temperatures, narrower foils prevent defect accumulation by releasing all defects at the free surfaces. Helium to DPA ratio is not shown to strongly change helium diffusivity in the range of irradiation conditions simulated. Frenkel pair implantation is shown to cause higher effective diffusivity and more complex diffusion mechanisms than cascade implantation. The results of these simulations indicate that the differences in damage rates between implantation experiments and fission or fusion environments may result in differences in the final microstructure.
Costello, Nessan; Deighton, Kevin; Preston, Thomas; Matu, Jamie; Rowe, Joshua; Sawczuk, Thomas; Halkier, Matt; Read, Dale B; Weaving, Daniel; Jones, Ben
2018-06-01
Collision sports are characterised by frequent high-intensity collisions that induce substantial muscle damage, potentially increasing the energetic cost of recovery. Therefore, this study investigated the energetic cost of collision-based activity for the first time across any sport. Using a randomised crossover design, six professional young male rugby league players completed two different 5-day pre-season training microcycles. Players completed either a collision (COLL; 20 competitive one-on-one collisions) or non-collision (nCOLL; matched for kinematic demands, excluding collisions) training session on the first day of each microcycle, exactly 7 days apart. All remaining training sessions were matched and did not involve any collision-based activity. Total energy expenditure was measured using doubly labelled water, the literature gold standard. Collisions resulted in a very likely higher (4.96 ± 0.97 MJ; ES = 0.30 ± 0.07; p = 0.0021) total energy expenditure across the 5-day COLL training microcycle (95.07 ± 16.66 MJ) compared with the nCOLL training microcycle (90.34 ± 16.97 MJ). The COLL training session also resulted in a very likely higher (200 ± 102 AU; ES = 1.43 ± 0.74; p = 0.007) session rating of perceived exertion and a very likely greater (- 14.6 ± 3.3%; ES = - 1.60 ± 0.51; p = 0.002) decrease in wellbeing 24 h later. A single collision training session considerably increased total energy expenditure. This may explain the large energy expenditures of collision-sport athletes, which appear to exceed kinematic training and match demands. These findings suggest fuelling professional collision-sport athletes appropriately for the "muscle damage caused" alongside the kinematic "work required".
Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria
Hunter, Eric J.
2015-01-01
Purpose Schoolteachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk. Method Vibration dosimetry is reformulated with the inclusion of collision stress. Two methods of estimating amplitude of vocal-fold vibration are compared to capture variations in vocal intensity. Energy loss from collision is added to the energy-dissipation dose. An equal-energy-dissipation criterion is defined and used on the teacher corpus as a potential-damage risk criterion. Results Comparison of time-, cycle-, distance-, and energy-dose calculations for 57 teachers reveals a progression in information content in the ability to capture variations in duration, speaking pitch, and vocal intensity. The energy-dissipation dose carries the greatest promise in capturing excessive tissue stress and collision but also the greatest liability, due to uncertainty in parameters. Cycle dose is least correlated with the other doses. Conclusion As a first guide to damage risk in excessive voice use, the equal-energy-dissipation dose criterion can be used to structure trade-off relations between loudness, adduction, and duration of speech. PMID:26172434
NASA Astrophysics Data System (ADS)
Csörgő, Tamás Hegyi, Sándor Kittel, Wolfram
The Table of Contents for the book is as follows: * Preface * QCD IN MULTIPARTICLE PRODUCTION * QCD and multiparticle production - The status of the perturbative cascade * Test of QCD predictions for multiparticle production at LEP * Multijet final states in e+e- annihilation * Tests of QCD in two photon physics at LEP * Interplay between perturbative and non-perturbative QCD in three-jet events * QCD and hadronic final states at the LHC * Transverse energy and minijets in high energy collisions * Multiparticle production at RHIC and LHC: A classical point of view * High energy interaction with the nucleus in the perturbative QCD with Nc → ∞ * DIFFRACTIVE PRODUCTION AND SMALL-x * Introduction to low-x physics and diffraction * Low-x physics at HERA * Diffractive structure functions at the Tevatron * What is the experimental evidence for the BFKL Pomeron? * Self-organized criticality in gluon systems and its consequences * Scale anomaly and dipole scattering in QCD * Pomeron and AdS/CFT correspondence for QCD * INTERPLAY BETWEEN SOFT AND HARD PHENOMENA * Inclusive jet cross sections and BFKL dynamics searches in dijet cross sections * Soft and hard interactions in p bar{p} Collisions at √ s = 1800 and 630 GeV * Recent results on particle production from OPAL * New results on αs and optimized scales * Preliminary results of the standard model Higgs boson search at LEP 2 in 2000 * Ways to go between hard and soft QCD * Alternative scenarios for fragmentation of a gluonic Lund String * A simultaneous measurement of the QCD colour charges and the strong coupling from LEP multijet data * Branching processes and Koenigs function * Soft and hard QCD dynamics in J/ψ hadroproduction * HADRONIC FINAL STATES IN 1+1, 1+h AND h+h REACTIONS * Universality in hadron production in electron-positron, lepton-hadron and hadron-hadron reactions * Search for gluonic mesons in gluon jets * Vector-to-pseudoscalar and meson-to-baryon ratios in hadronic Z decays at LEP * Polarization and spin alignment in multihadronic Z0 decays * Jet physics at HERA * Final state studies at HERA * A gauge-invariant subtraction technique for non-inclusive observables in QCD * Baryon transport in dual models and the possibility of a backward peak in diffraction * ASTROPARTICLE PHYSICS * Cosmic rays in the energy range of the knee - Recent results from KASCADE * Imaging atmospheric Čerenkov telescopes: Techniques and results * Extensive air shower simulations with CORSIKA and the influence of high-energy hadronic interaction models * Future directions in astroparticle physics and the AUGER experiment * p+A COLLISIONS * pp and pA collisions at CERN SPS * Charmonium attenuation and the quark-gluon plasma * Gluon depletion and J/ψ suppression in pA collisions * CORRELATIONS AND FLUCTUATIONS - EXPERIMENT * Experimental correlation analysis: Foundations and practice * Intermittency and correlations at LEP and at HERA * Moments of the charged-particle multiplicity distribution in Z decays at LEP * On the scale of visible jets in high energy electron-positron collisions * HBT in relativistic heavy ion collisions * Comparison of the pion emission function in hadron-hadron and heavy ion collisions * Multiparticle correlations at LEP1 * Inter-W Bose-Einstein correlations ellipse ... or not? * Colour reconnection at LEP2 * CORRELATIONS AND FLUCTUATIONS - THEORY * Correlations and fluctuations - introduction * Coherence and incoherence in Bose-Einstein correlations * Bose-Einstein correlations in cascade processes and non-extensive statistics * A systematic approach to anomalous phenomena at high energies * Reconstruction of hadronization stage in Pb+Pb collisions at 158A GeV/c * Status of ring-like correlations and wavelets * Fluctuation probes of quark deconfinement * PQCD structure and hadronization in jets and heavy-ion collisions * Net-baryon fluctuations at the QCD critical point * Fractional Fokker-Planck equation in time variable and oscillation of cumulant moments * QCD and multiplicity scaling * RELATIVISTIC HEAVY ION COLLISIONS - EXPERIMENT * Introduction to multiparticle dynamics at RHIC * First results from the STAR experiment at RHIC * Preliminary results from the PHENIX experiment at RHIC * Forward energy and multiplicity in Au-Au reactions at √ {s_{nn} } = 130{text{GeV}} * Results from the PHOBOS experiment on Au+Au collisions at RHIC * Strangeness production in Pb-Pb collisions at the CERN SPS: Results from the WA97 experiment * Direct photon production in 158A GeV 208Pb+208Pb collisions * Search for critical phenomena in Pb+Pb collisions * Recent NA49 results on Pb+Pb collisions at CERN SPS * J/ψ suppression in Pb+Pb collisions at CERN SPS * RELATIVISTIC HEAVY ION COLLISIONS - THEORY * Hyperon ratios at RHIC and the coalescence predictions at mid-rapidity * Dynamics of nuclear collisions and the dependence of the onset of anomalous J/ψ suppression on nucleon numbers of colliding nuclei * Multi-boson effects in Bose-Einstein interferometry * The source of the "third flow component" * Collective flow and multiparticle azimuthal correlations * Microscopic strangeness enhancement mechanisms at the SPS * Jet quenching at finite opacity and its application at RHIC energy * Particle rapidity density and collective phenomena in heavy ion collisions * Elliptic flow from an on-shell parton cascade * Dilepton production in ultrarelativistic heavy ion collisions * Coulomb and core/halo corrections to Bose-Einstein n-particle correlations * CP VIOLATION IN MULTIPARTICLE DYNAMICS * New results from NA48 experiment on neutral kaon rare decays * Measurement of direct CP violation by the NA48 experiment at CERN * Aspects of parity, CP, and time reversal violation in hot QCD * Decay of parity odd bubbles * Parity and time reversal studies at RHIC * Constraining CP-violating TGCS and measuring W-polarization at OPAL * Buckyballs of QCD: Gluon junction networks * List of participants
NASA Astrophysics Data System (ADS)
Zheng, Qiaofeng; Han, Baoguo; Ou, Jinping
2018-07-01
In this paper, a ship-bridge collision monitoring system based on flexible quantum tunneling composite (QTC) with cushioning capability is proposed by investigating the sensing capability and positioning capability of QTC to collisions. QTCs with different rubber matrix and thickness were fabricated, and collision tests between steel ball and QTCs sensors were designed to simulate ship-bridge collision. The results show that QTCs have a sensing range over 50 MPa with stress resolution ranging between 0.017 and 0.13 MPa, enough to achieve the full-time monitoring of ship-bridge collision. The system has instant and repeatable respond to impact load, and can accurately position the collisions. Moreover, QTC can remarkably absorb the kinetic energy during collisions, exhibiting excellent cushioning capability. These findings indicate the proposed ship-bridge collision monitoring system has great potential for application to detecting collision information such as collision occurrence and duration, impact load and collision location, as well as providing basis for citizen evacuation, post-accident damage estimation and rescue strategy.
NASA Astrophysics Data System (ADS)
Gao, Chan; Tian, Dongfeng; Li, Maosheng; Qian, Dazhi
2017-04-01
Different interatomic potentials produce displacement cascades with different features, and hence they significantly influence the results obtained from the displacement cascade simulations. The displacement cascade simulations in α-Fe have been carried out by molecular dynamics with three 'magnetic' potentials (MP) and Mendelev-type potential in this paper. Prior to the cascade simulations, the 'magnetic' potentials are hardened to suit for cascade simulations. We find that the peak time, maximum of defects, cascade volume and cascade density with 'magnetic' potentials are smaller than those with Mendelev-type potential. There is no significant difference within statistical uncertainty in the defect production efficiency with Mendelev-type potential and the second 'magnetic' potential at the same cascade energy, but remarkably smaller than those with the first and third 'magnetic' potential. Self interstitial atom (SIA) clustered fractions with 'magnetic' potentials are smaller than that with Mendelev-type potential, especially at the higher energy, due to the larger interstitial formation energies which result from the 'magnetic' potentials. The defect clustered fractions, which are input data for radiation damage accumulation models, may influence the prediction of microstructural evolution under radiation.
Cascading failures in interconnected networks with dynamical redistribution of loads
NASA Astrophysics Data System (ADS)
Zhao, Zhuang; Zhang, Peng; Yang, Hujiang
2015-09-01
Cascading failures of loads in isolated networks and coupled networks have been studied in the past few years. In most of the corresponding results, the topologies of the networks are destroyed. Here, we present an interconnected network model considering cascading failures based on the dynamic redistribution of flow in the networks. Compared with the results of single scale-free networks, we find that interconnected scale-free networks have higher vulnerability. Additionally, the network heterogeneity plays an important role in the robustness of interconnected networks under intentional attacks. Considering the effects of various coupling preferences, the results show that there are almost no differences. Finally, the application of our model to the Beijing interconnected traffic network, which consists of a subway network and a bus network, shows that the subway network suffers more damage under the attack. Moreover, the interconnected traffic network may be more exposed to damage after initial attacks on the bus network. These discussions are important for the design and optimization of interconnected networks.
NASA Astrophysics Data System (ADS)
Sahoo, Deepak Ranjan; Szlufarska, Izabela; Morgan, Dane; Swaminathan, Narasimhan
2018-01-01
Molecular dynamics simulations of displacement cascades were conducted to study the effect of point defects on the primary damage production in β-SiC. Although all types of point defects and Frenkel pairs were considered, Si interstitials and Si Frenkel pairs were unstable and hence excluded from the cascade studies. Si (C) vacancies had the maximum influence, enhancing C (Si) antisites and suppressing C interstitial production, when compared to the sample without any defects. The intracascade recombination mechanisms, in the presence of pre-existing defects, is explored by examining the evolution of point defects during the cascade. To ascertain the role of the unstable Si defects on amorphization, simulations involving explicit displacements of Si atoms were conducted. The dose to amorphization with only Si displacements was much lower than what was observed with only C displacements. The release of elastic energy accumulated due to Si defects, is found to be the amorphizing mechanism.
Mechanistic study of plasma damage to porous low-k: Process development and dielectric recovery
NASA Astrophysics Data System (ADS)
Shi, Hualiang
Low-k dielectrics with porosity are being introduced to reduce the RC delay of Cu/low-k interconnect. However, during the O2 plasma ashing process, the porous low-k dielectrics tend to degrade due to methyl depletion, moisture uptake, and densification, increasing the dielectric constant and leakage current. This dissertation presents a study of the mechanisms of plasma damage and dielectric recovery. The kinetics of plasma interaction with low-k dielectrics was investigated both experimentally and theoretically. By using a gap structure, the roles of ion, photon, and radical in producing damage on low-k dielectrics were differentiated. Oxidative plasma induced damage was proportional to the oxygen radical density, enhanced by VUV photon, and increased with substrate temperature. Ion bombardment induced surface densification, blocking radical diffusion. Two analytical models were derived to quantify the plasma damage. Based on the radical diffusion, reaction, and recombination inside porous low-k dielectrics, a plasma altered layer model was derived to interpret the chemical effect in the low ion energy region. It predicted that oxidative plasma induced damage can be reduced by decreasing pore radius, substrate temperature, and oxygen radical density and increasing carbon concentration and surface recombination rate inside low-k dielectrics. The model validity was verified by experiments and Monte-Carlo simulations. This model was also extended to the patterned low-k structure. Based on the ion collision cascade process, a sputtering yield model was introduced to interpret the physical effect in the high ion energy region. The model validity was verified by checking the ion angular and energy dependences of sputtering yield using O2/He/Ar plasma, low-k dielectrics with different k values, and a Faraday cage. Low-k dielectrics and plasma process were optimized to reduce plasma damage, including increasing carbon concentration in low-k dielectrics, switching plasma generator from ICP to RIE, increasing hard mask thickness, replacing O2 by CO2 plasma, increasing CO addition in CO/O 2 plasma, and increasing N2 addition in CO2/N 2 plasma. By combining analytical techniques with the Kramers-Kronig dispersion relation and quantum chemistry calculation, the origin of dielectric loss was ascribed to the physisorbed water molecules. Post-ash CH4 plasma treatment, vapor silylation process, and UV radiation were developed to repair plasma damage.
Free Radical Damage and Noise-Induced Hearing Loss: in vivo in situ Sensing
2008-07-01
e.g. imploding, locally nucleating bubbles23-26 ), leading to cellular damage? While ROS can kill cells, they are also part of the apoptotic cascade...reverse side. Electrodes are gold on Kaptonill substrates. Reference electrodes (Ir/IrxOy) are electrodeposited from IrC13 solution. Working
2009-03-31
Journal of the American Society for Mass Spectrometry, 2002. 13(2): p. 135- 143 . 7. Delcorte, A., P. Bertrand, and B.J. Garrison, Collision cascade and...TNCHP. 49, 50 The presence of the keto group in K6 appears to promote a more direct reaction to the gaseous decomposition products. Decomposition
Spatial Soliton Interactions for Photonic Switching. Part I
2000-03-07
solitons in geometries that allow for logically-complete, cascadable logic gates with fanout and level restoration. Detailed modeling will assist in...presented in Chapter 5. The first section covers the basic soliton interaction geometries useful for three-terminal, restoring logic, noting that the...collision and dragging geometries using orthogonally polarized solitons, which are of the general class of angular deflection gates, provide the best
Surface normal velocity distribution of sputtered Zr-atoms for light-ion irradiation
NASA Astrophysics Data System (ADS)
Bay, H. L.; Berres, W.; Hintz, E.
1982-03-01
The velocity distribution of sputtered Zr-atoms has been measured for 8 keV Ar + and He + ions and 2.5 keV D + ion irradiation at normal incidence. The measurements were performed with the aid of laser induced fluorescence spectroscopy (LIFS) using a CW-laser pumped dye-laser. The influence of the measuring geometry was investigated and found to be in good agreement with calculation. For light-ion sputtering the collision-cascade theory is no longer applicable. Here a distinct shift in the velocity distributions towards lower velocities compared with the Ar results was found. The shift can be correlated to anisotropic effects in connection with the change in the maximum recoil energy Tm in the cascade.
NASA Astrophysics Data System (ADS)
Matthaeus, W. H.; Yang, Y.; Servidio, S.; Parashar, T.; Chasapis, A.; Roytershteyn, V.
2017-12-01
Turbulence cascade transfers energy from large scale to small scale but what happens once kinetic scales are reached? In a collisional medium, viscosity and resistivity remove fluctuation energy in favor of heat. In the weakly collisional solar wind, (or corona, m-sheath, etc.), the sequence of events must be different. Heating occurs, but through what mechanisms? In standard approaches, dissipation occurs though linear wave modes or instabilities and one seeks to identify them. A complementary view is that cascade leads to several channels of energy conversion, interchange and spatial rearrangement that collectively leads to production of internal energy. Channels may be described using compressible MHD & multispecies Vlasov Maxwell formulations. Key steps are: Conservative rearrangement of energy in space; Parallel incompressible and compressible cascades - conservative rearrangment in scale; electromagnetic work on particles that drives flows, both macroscopic and microscopic; and pressure-stress interactions, both compressive and shear-like, that produces internal energy. Examples given from MHD, PIC simulations and MMS observations. A more subtle issue is how entropy is related to this degeneration (or, "dissipation") of macroscopic, fluid-scale fluctuations. We discuss this in terms of Boltzmann and thermodynamic entropies, and velocity space effects of collisions.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.
2015-07-01
The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibitsmore » an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.« less
Computer simulation of radiation damage in gallium arsenide
NASA Technical Reports Server (NTRS)
Stith, John J.; Davenport, James C.; Copeland, Randolph L.
1989-01-01
A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.
Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie
2017-01-01
Measuring the radial collision force between the steam generator tube (SGT) and the tube support plate (TSP) is essential to assess the fretting damage of the SGT. In order to measure the radial collision force, a novel miniaturized force sensor based on fiber Fabry-Perot (F-P) was designed, and the principle and characteristics of the sensor were analyzed in detail. Then, the F-P force sensor was successfully fabricated and calibrated, and the overall dimensions of the encapsulated fiber F-P sensor were 17 mm × 5 mm × 3 mm (L × W × H). The sensor works well in humid, high pressure (10 MPa), high temperature (350 °C), and vibration (40 kHz) environments. Finally, the F-P force sensors were installed in a 1:1 steam generator test loop, and the radial collision force signals between the SGT and the TSP were obtained. The experiments indicated that the F-P sensor with small volume and high performance could help in assessing the fretting damage of the steam generator tubes. PMID:29236087
Improved Strength and Damage Modeling of Geologic Materials
NASA Astrophysics Data System (ADS)
Stewart, Sarah; Senft, Laurel
2007-06-01
Collisions and impact cratering events are important processes in the evolution of planetary bodies. The time and length scales of planetary collisions, however, are inaccessible in the laboratory and require the use of shock physics codes. We present the results from a new rheological model for geological materials implemented in the CTH code [1]. The `ROCK' model includes pressure, temperature, and damage effects on strength, as well as acoustic fluidization during impact crater collapse. We demonstrate that the model accurately reproduces final crater shapes, tensile cracking, and damaged zones from laboratory to planetary scales. The strength model requires basic material properties; hence, the input parameters may be benchmarked to laboratory results and extended to planetary collision events. We show the effects of varying material strength parameters, which are dependent on both scale and strain rate, and discuss choosing appropriate parameters for laboratory and planetary situations. The results are a significant improvement in models of continuum rock deformation during large scale impact events. [1] Senft, L. E., Stewart, S. T. Modeling Impact Cratering in Layered Surfaces, J. Geophys. Res., submitted.
Philpott, Stacy M; Pardee, Gabriella L; Gonthier, David J
2012-05-01
Interactions between predators and the degree of functional redundancy among multiple predator species may determine whether herbivores experience increased or decreased predation risk. Specialist parasites can modify predator behavior, yet rarely have cascading effects on multiple predator species and prey been evaluated. We examined influences of specialist phorid parasites (Pseudacteon spp.) on three predatory ant species and herbivores in a coffee agroecosystem. Specifically, we examined whether changes in ant richness affected fruit damage by the coffee berry borer (Hypothenemus hampei) and whether phorids altered multi-predator effects. Each ant species reduced borer damage, and without phorids, increasing predator richness did not further decrease borer damage. However, with phorids, activity of one ant species was reduced, indicating that the presence of multiple ant species was necessary to limit borer damage. In addition, phorid presence revealed synergistic effects of multiple ant species, not observed without the presence of this parasite. Thus, a trait-mediated cascade resulting from a parasite-induced predator behavioral change revealed the importance of functional redundancy, predator diversity, and food web complexity for control of this important pest.
An ab initio study of ion induced charge transfer dynamics in collision of carbon ions with thymine.
Bacchus-Montabonel, Marie-Christine; Tergiman, Yvette Suzanne
2011-05-28
Charge transfer in collisions of carbon ions on a thymine target has been studied theoretically in a wide collision range by means of ab initio quantum chemistry molecular methods. The process appears markedly anisotropic in the whole energy domain, significantly favoured in the perpendicular orientation. A specific decrease of the charge transfer cross sections at low collision energies may be pointed out and could induce an enhancement of the complementary fragmentation processes for collision energies down to about 10 eV, as observed for the low-electron fragmentation process. Such feature may be of important interest in ion-induced biomolecular radiation damage. This journal is © the Owner Societies 2011
33 CFR 70.05-10 - Revocation of merchant mariner credential officer endorsement or license.
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Qualification and Testing of Quantum Cascade Lasers for Harsh Environments
NASA Astrophysics Data System (ADS)
Brauer, C. S.; Myers, T. L.; Cannon, B. D.; Anderson, C. G.; Crowther, B. G.; Hansen, S.
2014-12-01
Quantum cascade lasers (QCLs) offer the potential for the development of novel, laser-based instruments for both terrestrial and space applications. In order to withstand harsh conditions encountered in these environments, lasers must be robust, and rigorous testing is required before new systems can be utilized. A particular concern for space applications is the potential damage to laser performance caused by radiation exposure. While the effects of radiation exposure in diode lasers have been studied extensively, the effect on QCLs, which are fundamentally different from diode lasers, is not well known. We thus present work to quantify the performance of QCLs after exposure to moderate and high levels of radiation from different sources, including protons and gamma rays, to determine the effects of radiation damage.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Myhra, S., E-mail: sverre.myhra@materials.ox.ac.uk; Chakalova, R.; Falzone, N.
A method for detection and characterization of single MeV α-particle and recoil tracks in PMMA photoresist by atomic force microscopy (AFM) analysis has been demonstrated. The energy deposition along the track is shown to lead to a latent pattern in the resist due to contrast reversal. It has been shown that the pattern, consisting of conical spikes, can be developed by conventional processing as a result of the dissolution rate of poly(methyl methacrylate) (PMMA) being greater than that for the modified material in the cylindrical volume of the track core. The spikes can be imaged and counted by routine AFMmore » analysis. Investigations by angular-resolved near-grazing incidence reveal additional tracks that correspond to recoil tracks. The observations have been correlated with modelling, and shown to be in qualitative agreement with prevailing descriptions of collision cascades. The results may be relevant to technologies that are based on detection and characterization of single energetic ions. In particular, the direct visualization of the collision cascade may allow more accurate estimates of the actual interaction volume, which in turn will permit more precise assessment of dose distribution of α-emitting radionuclides used for targeted radiotherapy. The results could also be relevant to other diagnostic or process technologies based on interaction of energetic ions with matter.« less
NASA Astrophysics Data System (ADS)
Gupta, P.; Williams, G. V. M.; Hübner, R.; Vajandar, S.; Osipowicz, T.; Heinig, K.-H.; Becker, H.-W.; Markwitz, A.
2017-04-01
Mono-energetic cobalt implantation into hydrogenated diamond-like carbon at room temperature results in a bimodal distribution of implanted atoms without any thermal treatment. The ˜100 nm thin films were synthesised by mass selective ion beam deposition. The films were implanted with cobalt at an energy of 30 keV and an ion current density of ˜5 μA cm-2. Simulations suggest the implantation profile to be single Gaussian with a projected range of ˜37 nm. High resolution Rutherford backscattering measurements reveal that a bimodal distribution evolves from a single near-Gaussian distribution as the fluence increases from 1.2 to 7 × 1016 cm-2. Cross-sectional transmission electron microscopy further reveals that the implanted atoms cluster into nanoparticles. At high implantation doses, the nanoparticles assemble primarily in two bands: one near the surface with nanoparticle diameters of up to 5 nm and the other beyond the projected range with ˜2 nm nanoparticles. The bimodal distribution along with the nanoparticle formation is explained with diffusion enhanced by energy deposited during collision cascades, relaxation of thermal spikes, and defects formed during ion implantation. This unique distribution of magnetic nanoparticles with the bimodal size and range is of significant interest to magnetic semiconductor and sensor applications.
NASA Astrophysics Data System (ADS)
Gupta, P.; Becker, H.-W.; Williams, G. V. M.; Hübner, R.; Heinig, K.-H.; Markwitz, A.
2017-03-01
Hydrogenated diamond-like carbon films produced by C3H6 deposition at 5 kV and implanted at room temperature with 30 keV Co atoms to 12 at.% show not only a bimodal distribution of Co atoms but also a massive redistribution of hydrogen in the films. Resonant nuclear reaction analysis was used to measure the hydrogen depth profiles (15N-method). Depletion of hydrogen near the surface was measured to be as low as 7 at.% followed by hydrogen accumulation from 27 to 35 at.%. A model is proposed considering the thermal energy deposited by collision cascade for thermal insulators. In this model, sufficient energy is provided for dissociated hydrogen to diffuse out of the sample from the surface and diffuse into the sample towards the interface which is however limited by the range of the incoming Co ions. At a hydrogen concentration of ∼35 at.%, the concentration gradient of the mobile unbounded hydrogen atoms is neutralised effectively stopping diffusion towards the interface. The results point towards new routes of controlling the composition and distribution of elements at the nanoscale within a base matrix without using any heat treatment methods. Exploring these opportunities can lead to a new horizon of materials and device engineering needed for enabling advanced technologies and applications.
Triangular flow of negative pions emitted in PbAu collisions at √{sNN} = 17.3 GeV
NASA Astrophysics Data System (ADS)
Adamová, D.; Agakichiev, G.; Andronic, A.; Antończyk, D.; Appelshäuser, H.; Belaga, V.; Bielčíková, J.; Braun-Munzinger, P.; Busch, O.; Cherlin, A.; Damjanović, S.; Dietel, T.; Dietrich, L.; Drees, A.; Dubitzky, W.; Esumi, S. I.; Filimonov, K.; Fomenko, K.; Fraenkel, Z.; Garabatos, C.; Glässel, P.; Hering, G.; Holeczek, J.; Kalisky, M.; Karpenko, Iu.; Krobath, G.; Kushpil, V.; Maas, A.; Marín, A.; Milošević, J.; Miśkowiec, D.; Panebrattsev, Y.; Petchenova, O.; Petráček, V.; Radomski, S.; Rak, J.; Ravinovich, I.; Rehak, P.; Sako, H.; Schmitz, W.; Schuchmann, S.; Sedykh, S.; Shimansky, S.; Stachel, J.; Šumbera, M.; Tilsner, H.; Tserruya, I.; Tsiledakis, G.; Wessels, J. P.; Wienold, T.; Wurm, J. P.; Yurevich, S.; Yurevich, V.
2017-01-01
Differential triangular flow, v3 (pT), of negative pions is measured at √{sNN} = 17.3 GeV around midrapidity by the CERES/NA45 experiment at CERN in central PbAu collisions in the range 0-30% with a mean centrality of 5.5%. This is the first measurement as a function of transverse momentum of the triangular flow at SPS energies. The pT range extends from about 0.05 GeV/c to more than 2 GeV/c. The triangular flow magnitude, corrected for the HBT effects, is smaller by a factor of about 2 than the one measured by the PHENIX experiment at RHIC and the ALICE experiment at the LHC. Within the analyzed range of central collisions no significant centrality dependence is observed. The data are found to be well described by a viscous hydrodynamic calculation combined with an UrQMD cascade model for the late stages.
NASA Astrophysics Data System (ADS)
Silsbee, Kedron; Rafikov, Roman
2017-06-01
The existence of planets in tight binary systems presents an interesting puzzle. It is thought that cores of giant planets form via agglomeration of planetesimals in mutual collisions. However, in tight binary systems, one would naïvely expect the collision velocities between planetesimals to be so high that even 100 km bodies would be destroyed, rather than growing in mutual collisions. In these systems, planetesimals are perturbed by gravity from the companion star, and gravity and gas drag from a massive eccentric gas disk. There is a damaging secular resonance that occurs due to the combination of disk gravity and gravity from the binary companion, however the disk gravity can also create locations of low relative eccentricity between planetesimals of different sizes that would not exist if the disk gravity were ignored. Because the gas drag acts more strongly on smaller planetesimals, orbital eccentricity and apsidal angle depend on planetesimal size. Consequently, planetesimal collision velocities depend on the sizes of the collision partners. Same-size bodies collide at low velocity because their orbits are apsidally aligned. Therefore, often in a given environment some collisions will lead to planetesimal growth, and some to erosion or destruction. This variety of collisional outcomes makes it difficult to determine whether any planetesimals can grow to large sizes. We run a multi-annulus coagulation/fragmentation simulation that also includes the effect of size-dependent radial drift of planetesimals to determine the minimum size of initial planetesimal necessary for growth to large sizes in collisions. The minimum initial size of planetesimal necessary for growth depends greatly on the disk mass, eccentricity and the degree of apsidal alignment with the binary. We find that in a wide variety of situations, it is a reasonable approximation that growth occurs as long as there are no collisions capable of completely destroying a planetesimal, but erosion by moderately damaging collisions can also prevent growth from occurring.
Design and evaluation of safety operation VR training system for robotic catheter surgery.
Wang, Yu; Guo, Shuxiang; Li, Yaxin; Tamiya, Takashi; Song, Yu
2018-01-01
A number of remote robotic catheter systems have been developed to protect physicians from X-ray exposure in endovascular surgery. However, the teleoperation prevents the physicians sensing the force directly which may easily result in healthy vessels injured. To realize the safe operation, a tissue protection-based VR training system has been developed in this paper to prevent collateral damage by collision. The integrated VR simulator cannot only remind the novice possible collisions by visual signs, but also cooperate with the newly designed tissue protection mechanism to remit collision trauma beforehand. Such mechanism exploits the diameter variable pulley in order to implement the safe interaction between catheter and vasculature. To testify the effectiveness of the tissue protection in training system, we invited four non-medical students to participate the successive 5 days training session. The evaluation results show that the average impingement distance (representing tissue damage) to vascular wall has been reduced to 0.6 mm, and the collision frequency is greatly decreased which implies the realization of relative safe catheterization.
Liu, Xing; Zhou, Binbin; Guo, Hairun; Bache, Morten
2015-08-15
We show numerically that ultrashort self-defocusing temporal solitons colliding with a weak pulsed probe in the near-IR can convert the probe to the mid-IR. A near-perfect conversion efficiency is possible for a high effective soliton order. The near-IR self-defocusing soliton can form in a quadratic nonlinear crystal (beta-barium borate) in the normal dispersion regime due to cascaded (phase-mismatched) second-harmonic generation, and the mid-IR converted wave is formed in the anomalous dispersion regime between λ=2.2-2.4 μm as a resonant dispersive wave. This process relies on nondegenerate four-wave mixing mediated by an effective negative cross-phase modulation term caused by cascaded soliton-probe sum-frequency generation.
Using a Classical Gluon Cascade to study the Equilibration of a Gluon-Plasma
NASA Astrophysics Data System (ADS)
McConnell, Lucas
2015-10-01
Using a classical gluon cascade, we study the thermalisation of a gluon-plasma in a homogeneous box by considering the time evolution of the entropy, and in particular how the thermalisation time depends on the strong coupling αs. We then partition the volume into cells with a linearly increasing temperature gradient in one direction, and homogeneous/isotropic in the the other two directions. We allow the gluons to stream in one direction in order to study how they then evolve spatially. We examine cases with and without collisions. We study the entropy as well as the flow-velocity in the z-direction and find that the system initially has a flow which dissipates over time as the gluons become distributed homogeneously throughout the box.
Space Debris Environment Remediation Concepts
NASA Technical Reports Server (NTRS)
Johnson, Nicholas L.; Klinkrad, Heiner
2009-01-01
Long-term projections of the space debris environment indicate that even drastic measures, such as an immediate, complete halt of launch and release activities, will not result in a stable environment of man-made space objects. Collision events between already existing space hardware will within a few decades start to dominate the debris population, and result in a net increase of the space debris population, also in size regimes which may cause further catastrophic collisions. Such a collisional cascading will ultimately lead to a run-away situation ("Kessler syndrome"), with no further possibility of human intervention. The International Academy of Astronautics (IAA) has been investigating the status and the stability of the space debris environment in several studies by first looking into space traffic management possibilities and then investigating means of mitigating the creation of space debris. In an ongoing activity, an IAA study group looks at ways of active space debris environment remediation. In contrast to the former mitigation study, the current activity concentrates on the active removal of small and large objects, such as defunct spacecraft, orbital stages, and mission-related objects, which serve as a latent mass reservoir that fuels initial catastrophic collisions and later collisional cascading. The paper will outline different mass removal concepts, e.g. based on directed energy, tethers (momentum exchange or electrodynamic), aerodynamic drag augmentation, solar sails, auxiliary propulsion units, retarding surfaces, or on-orbit capture. Apart from physical principles of the proposed concepts, their applicability to different orbital regimes, and their effectiveness concerning mass removal efficiency will be analyzed. The IAA activity on space debris environment remediation is a truly international project which involves more than 23 contributing authors from 9 different nations.
Ionization Cross Sections and Dissociation Channels of DNA Bases by Electron Collisions
NASA Technical Reports Server (NTRS)
Huo, Winifred M.; Dateo, Christopher E.; Fletcher, Graham D.
2004-01-01
Free secondary electrons are the most abundant secondary species in ionizing radiation. Their role in DNA damage, both direct and indirect, is an active area of research. While indirect damage by free radicals, particularly by the hydroxyl radical generated by electron collision with water. is relatively well studied, damage by direct electron collision with DNA is less well understood. Only recently Boudaiffa et al. demonstrated that electrons at energies well below ionization thresholds can induce substantial yields of single- and double-strand breaks in DNA by a resonant, dissociative attachment process. This study attracted renewed interest in electron collisions with DNA, especially in the low energy region. At higher energies ionization becomes important. While Monte Carlo track simulations of radiation damage always include ionization, the probability of dissociative ionization, i.e., simultaneous ionization and dissociation, is ignored. Just like dissociative attachment, dissociative ionization may be an important contributor to double-strand breaks since the radicals and ions produced by dissociative ionization, located in the vicinity of the DNA coil, can readily interact with other parts of the DNA. Using the improved binary-encounter dipole (iBED) formulation, we calculated the ionization cross sections of the four DNA bases, adenine, cytosine, guanine, and thymine, by electrons at energies from threshold to 1 KeV. The present calculation gives cross sections approximately 20% lower than the results by Bemhardt and Paretzke using the Deutsch-Mark and Binary-Encounter-Bethe (BEB) formalisms. The difference is most likely due to the lack of a shielding term in the dipole potential used in the Deutsch-Mark and BEB formalisms. The dissociation channels of ionization for the bases are currently being studied.
Leonov, S V; Pinchuk, P V; Shakir'janova, Ju P
This article was designed to report the results of the analysis of the consequences of a real case of the sidewise collision and run-over involving a pedestrian and an automobile moving in the reverse gear along an arc of a circle. Special attention was given to the mechanism behind the collision, its peculiar features, and characteristic damages inflicted to the pedestrian's body and clothes.
Survey of Recent Results from the PHOBOS Experiment at RHIC
NASA Astrophysics Data System (ADS)
Roland, Christof; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.
2002-10-01
We present an overview of the latest results for interactions of Au+Au ions at center-of-mass energies of √SNN of 56, 130 and 200 GeV obtained by the PHOBOS collaboration at the Relativistic Heavy Ion Collider (RHIC). These data have allowed us to perform an extensive study of the pseudorapidity density of primary charged particles as a function of incident energy, centrality and pseudorapidity. Our results show a non-trivial evolution of particle densities with both centrality and collision energy, reaching significantly higher values per participating nucleon than at lower energies or in nucleon-nucleon collisions. Further we present results on the azimuthal asymmetry of particle production observed in the √SNN of 130 GeV data set. The observed strong event anisotropy of v2max > 0.06, reaching beyond the value predicted in hadronic cascade models, indicates a closer approach to local thermal equilibration than at lower collision energies. The measured antiparticle-particle ratios of production rates for pions kaons and protons in central Au+Au interactions at √SNN of 130 GeV are compatible with predictions from statistical models, showing an approach to a baryon free region in mid-rapidity with the increase in collision energy.
NASA Astrophysics Data System (ADS)
Gao, Chan; Tian, Dongfeng; Li, Maosheng; Qian, Dazhi
2018-03-01
In fusion applications, helium, implanted or created by transmutation, plays an important role in the response of reduced-activation ferritic/martensitic steels to neutron radiation damage. The effects of helium concentration and radiation temperature on interaction of interstitial helium atoms with displacement cascades have been studied in Fe-He system using molecular dynamics with recently developed Fe-He potential. Results indicate that interstitial helium atoms produce no additional defects at peak time and promote recombination of Frenkel pairs at lower helium concentrations, but suppress recombination of Frenkel pairs at larger helium concentrations. Moreover, large helium concentrations promote the production of defects at the end of cascades. The number of substitutional helium atoms increases with helium concentration at peak time and the end of cascades, but the number of substitutional helium atoms at peak time is smaller than that at the end of displacement cascades. High radiation temperatures promote the production at peak time and the recombination of defects at the end of cascades. The number of substitutional helium atoms increases with radiation temperature, but that at peak time is smaller than that at the end of cascades.
NASA Astrophysics Data System (ADS)
Henriksson, K. O. E.
2015-06-01
Ferritic stainless steel can be modeled as an iron matrix containing precipitates of cementite (Fe3C) and Cr23C6. When used in nuclear power production the steels in the vicinity of the core start to accumulate damage due to neutrons. The role of the afore-mentioned carbides in this process is not well understood. In order to clarify the situation bulk cascades created by primary recoils in model steels have been carried out in the present work. Investigated configurations consisted of bulk ferrite containing spherical particles (diameter of 4 nm) of either (1) Fe3C or (2) Cr23C6. Primary recoils were initiated at different distances from the inclusions, with recoil energies varying between 100 eV and 1 keV. Results for the number of point defects such as vacancies and antisites are presented. These findings indicate that defects are also remaining when cascades are started outside the carbide inclusions. The work uses a recently developed Abell-Brenner-Tersoff potential for the Fe-Cr-C system.
Auden, Elizabeth C.; Pacheco, Jose L.; Bielejec, Edward; ...
2015-12-01
In this study, displacement damage reduces ion beam induced charge (IBIC) through Shockley-Read-Hall recombination. Closely spaced pulses of 200 keV Si ++ ions focused in a 40 nm beam spot are used to create damage cascades within 0.25 μm 2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of 200 keV Si ++ ions and 60 keV Li + ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Auden, Elizabeth C.; Pacheco, Jose L.; Bielejec, Edward
In this study, displacement damage reduces ion beam induced charge (IBIC) through Shockley-Read-Hall recombination. Closely spaced pulses of 200 keV Si ++ ions focused in a 40 nm beam spot are used to create damage cascades within 0.25 μm 2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of 200 keV Si ++ ions and 60 keV Li + ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions.
Collision Detection for Underwater ROV Manipulator Systems
Rossi, Matija; Dooly, Gerard; Toal, Daniel
2018-01-01
Work-class ROVs equipped with robotic manipulators are extensively used for subsea intervention operations. Manipulators are teleoperated by human pilots relying on visual feedback from the worksite. Operating in a remote environment, with limited pilot perception and poor visibility, manipulator collisions which may cause significant damage are likely to happen. This paper presents a real-time collision detection algorithm for marine robotic manipulation. The proposed collision detection mechanism is developed, integrated into a commercial ROV manipulator control system, and successfully evaluated in simulations and experimental setup using a real industry standard underwater manipulator. The presented collision sensing solution has a potential to be a useful pilot assisting tool that can reduce the task load, operational time, and costs of subsea inspection, repair, and maintenance operations. PMID:29642396
Collision Detection for Underwater ROV Manipulator Systems.
Sivčev, Satja; Rossi, Matija; Coleman, Joseph; Omerdić, Edin; Dooly, Gerard; Toal, Daniel
2018-04-06
Work-class ROVs equipped with robotic manipulators are extensively used for subsea intervention operations. Manipulators are teleoperated by human pilots relying on visual feedback from the worksite. Operating in a remote environment, with limited pilot perception and poor visibility, manipulator collisions which may cause significant damage are likely to happen. This paper presents a real-time collision detection algorithm for marine robotic manipulation. The proposed collision detection mechanism is developed, integrated into a commercial ROV manipulator control system, and successfully evaluated in simulations and experimental setup using a real industry standard underwater manipulator. The presented collision sensing solution has a potential to be a useful pilot assisting tool that can reduce the task load, operational time, and costs of subsea inspection, repair, and maintenance operations.
Repair of impact damaged utility poles with fiber reinforced polymers (FRP), phase II.
DOT National Transportation Integrated Search
2015-06-01
Vehicle collisions with steel or aluminum utility poles are common occurrences that yield substantial but often repairable : damage. This project investigates the use of a fiber-reinforced polymer (FRP) composite system for in situ repair that : mini...
Relativistic Shock Waves in Viscous Gluon Matter
NASA Astrophysics Data System (ADS)
Bouras, I.; Molnár, E.; Niemi, H.; Xu, Z.; El, A.; Fochler, O.; Greiner, C.; Rischke, D. H.
2009-07-01
We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio η/s from zero to infinity. We show that an η/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.
Hippo pathway and protection of genome stability in response to DNA damage.
Pefani, Dafni E; O'Neill, Eric
2016-04-01
The integrity of DNA is constantly challenged by exposure to the damaging effects of chemical and physical agents. Elucidating the cellular mechanisms that maintain genomic integrity via DNA repair and cell growth control is vital because errors in these processes lead to genomic damage and the development of cancer. By gaining a deep molecular understanding of the signaling pathways regulating genome integrity it is hoped to uncover new therapeutics and treatment designs to combat cancer. Components of the Hippo pathway, a tumor-suppressor cascade, have recently been defined to limit cancer transformation in response to DNA damage. In this review, we briefly introduce the Hippo signaling cascade in mammals and discuss in detail how the Hippo pathway has been established as part of the DNA damage response, activated by apical signaling kinases that recognize breaks in DNA. We also highlight the significance of the Hippo pathway activator RASSF1A tumor suppressor, a direct target of ataxia telangiectasia mutated and ataxia telangiectasia and Rad3 related ATR. Furthermore we discuss how Hippo pathway in response DNA lesions can induce cell death via Yes-associated protein (YAP) (the canonical Hippo pathway effector) or promote maintenance of genome integrity in a YAP-independent manner. © 2015 FEBS.
NASA Astrophysics Data System (ADS)
Prabowo, A. R.; Baek, S. J.; Lee, S. G.; Bae, D. M.; Sohn, J. M.
2018-01-01
Phenomena of impact loads on the marine structures has attracted attention to be predicted regarding its influences to structural damage. This part demands sustainable analysis and observation as tendency may vary from one to others since impact involves various scenario models and the structure itself experiences continuous development. Investigation of the damage extent can be conducted by observation on the energy behaviour during two entities involve in a contact. This study aimed to perform numerical investigation to predict structural damage by assessing absorbed strain energy represented by the internal energy during a series of ship collisions. The collision target in ship-ship interactions were determined on the single and double hulls part of a passenger ship. Tendency of the internal energy by the steel structures was summarized, and verification was presented by several crashworthiness criteria. It was found that steel structures applied by the material grades A and B produced different tendencies compared to the material grades D and E. Effect of the structural arrangement to structural responses in terms of strain and stress indicated that the single hull presented contour expansion mainly on the longitudinal directions.
Three-dimensional Cascaded Lattice Boltzmann Model for Thermal Convective Flows
NASA Astrophysics Data System (ADS)
Hajabdollahi, Farzaneh; Premnath, Kannan
2017-11-01
Fluid motion driven by thermal effects, such as due to buoyancy in differentially heated enclosures arise in several natural and industrial settings, whose understanding can be achieved via numerical simulations. Lattice Boltzmann (LB) methods are efficient kinetic computational approaches for coupled flow physics problems. In this study, we develop three-dimensional (3D) LB models based on central moments and multiple relaxation times for D3Q7 and D3Q15 lattices to solve the energy transport equations in a double distribution function approach. Their collision operators lead to a cascaded structure involving higher order terms resulting in improved stability. This is coupled to a central moment based LB flow solver with source terms. The new 3D cascaded LB models for the convective flows are first validated for natural convection of air driven thermally on two vertically opposite faces in a cubic cavity at different Rayleigh numbers against prior numerical and experimental data, which show good quantitative agreement. Then, the detailed structure of the 3D flow and thermal fields and the heat transfer rates at different Rayleigh numbers are analyzed and interpreted.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.
A search for heavy narrow resonances decaying into four-lepton final states from cascade decays of a Z' boson has been performed using proton-proton collision data atmore » $$\\sqrt{s}$$ = 8 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 19.7 inverse femtobarns. No excess of events over the standard model background expectation is observed. Upper limits for a benchmark model on the product of cross section and branching fraction for the production of these heavy narrow resonances are presented. The limit excludes leptophobic Z' bosons with masses below 2.5 TeV within the benchmark model. This is the first result to constrain a leptophobic Z' resonance in the four-lepton channel.« less
Laboratory experiments on soft x-ray emissions from the solar wind
NASA Astrophysics Data System (ADS)
Kanda, T.; Ohashi, H.; Maeno, S.; Ishida, T.; Tanuma, H.; Akamatsu, H.; Abe, Y.; Yokota, W.; Henmi, K.; Ishisaki, Y.; Ezoe, Y.; Ohashi, T.; Shinozaki, K.; Mitsuda, K.
2011-06-01
We have observed emission spectra in collisions of hydrogen-like oxygen and nitrogen ions with a helium target gas in the soft x-ray region using a window-less Si(Li) detector at collision energies of about 100 keV. The dominant soft x-ray emission is the 1s2-1s2p transition of helium-like ions produced by a single-electron capture reaction. We indicate that the cascades from the upper states give a large population of the 2p state, even though direct capture into the 2p state is much smaller than the 3ell and 4ell states. The intensity ratios of the 1s-2p and 1s-3p transitions are discussed, along with a comparison with the theoretical calculation.
Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; ...
2017-09-06
A search for heavy narrow resonances decaying into four-lepton final states from cascade decays of a Z' boson has been performed using proton-proton collision data atmore » $$\\sqrt{s}$$ = 8 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 19.7 inverse femtobarns. No excess of events over the standard model background expectation is observed. Upper limits for a benchmark model on the product of cross section and branching fraction for the production of these heavy narrow resonances are presented. The limit excludes leptophobic Z' bosons with masses below 2.5 TeV within the benchmark model. This is the first result to constrain a leptophobic Z' resonance in the four-lepton channel.« less
Cascade debris overlap mechanism of 〈100〉 dislocation loop formation in Fe and FeCr
NASA Astrophysics Data System (ADS)
Granberg, F.; Byggmästar, J.; Sand, A. E.; Nordlund, K.
2017-09-01
Two types of dislocation loops are observed in irradiated α-Fe, the 1/2〈111〉 loop and the 〈100〉 loop. Atomistic simulations consistently predict that only the energetically more favourable 1/2〈111〉 loops are formed directly in cascades, leaving the formation mechanism of 〈100〉 loops an unsolved question. We show how 〈100〉 loops can be formed when cascades overlap with random pre-existing primary radiation damage in Fe and FeCr. This indicates that there are no specific constraints involved in the formation of 〈100〉 loops, and can explain their common occurrence.
Schmidt-Erfurth, Ursula; van Lookeren Campagne, Menno; Henry, Erin C.; Brittain, Christopher
2017-01-01
Purpose: Geographic atrophy (GA) is an advanced, vision-threatening form of age-related macular degeneration (AMD) affecting approximately five million individuals worldwide. To date, there are no approved therapeutics for GA treatment; however, several are in clinical trials. This review focuses on the pathophysiology of GA, particularly the role of complement cascade dysregulation and emerging therapies targeting the complement cascade. Methods: Primary literature search on PubMed for GA, complement cascade in age-related macular degeneration. ClinicalTrials.gov was searched for natural history studies in GA and clinical trials of drugs targeting the complement cascade for GA. Results: Cumulative damage to the retina by aging, environmental stress, and other factors triggers inflammation via multiple pathways, including the complement cascade. When regulatory components in these pathways are compromised, as with several GA-linked genetic risk factors in the complement cascade, chronic inflammation can ultimately lead to the retinal cell death characteristic of GA. Complement inhibition has been identified as a key candidate for therapeutic intervention, and drugs targeting the complement pathway are currently in clinical trials. Conclusion: The complement cascade is a strategic target for GA therapy. Further research, including on natural history and genetics, is crucial to expand the understanding of GA pathophysiology and identify effective therapeutic targets. PMID:27902638
DOE Office of Scientific and Technical Information (OSTI.GOV)
Korovin, Yu. A.; Maksimushkina, A. V., E-mail: AVMaksimushkina@mephi.ru; Frolova, T. A.
2016-12-15
The cross sections of nuclear reactions involving emission of clusters of light nuclei in proton collisions with a heavy-metal target are computed for incident-proton energies between 30 MeV and 2.6 GeV. The calculation relies on the ALICE/ASH and CASCADE/INPE computer codes. The parameters determining the pre-equilibrium cluster emission are varied in the computation.
Code of Federal Regulations, 2011 CFR
2011-07-01
... ALLOWABLE TRAVEL EXPENSES 10-TRANSPORTATION EXPENSES Special Conveyances Rental Automobiles § 301-10.451 May... Government includes full coverage insurance for damages resulting from an accident while performing official... cause extreme difficulty for an employee involved in an accident. ...
Code of Federal Regulations, 2013 CFR
2013-07-01
... ALLOWABLE TRAVEL EXPENSES 10-TRANSPORTATION EXPENSES Special Conveyances Rental Automobiles § 301-10.451 May... Government includes full coverage insurance for damages resulting from an accident while performing official... cause extreme difficulty for an employee involved in an accident. ...
Code of Federal Regulations, 2012 CFR
2012-07-01
... ALLOWABLE TRAVEL EXPENSES 10-TRANSPORTATION EXPENSES Special Conveyances Rental Automobiles § 301-10.451 May... Government includes full coverage insurance for damages resulting from an accident while performing official... cause extreme difficulty for an employee involved in an accident. ...
Code of Federal Regulations, 2014 CFR
2014-07-01
... ALLOWABLE TRAVEL EXPENSES 10-TRANSPORTATION EXPENSES Special Conveyances Rental Automobiles § 301-10.451 May... Government includes full coverage insurance for damages resulting from an accident while performing official... cause extreme difficulty for an employee involved in an accident. ...
Code of Federal Regulations, 2010 CFR
2010-07-01
... ALLOWABLE TRAVEL EXPENSES 10-TRANSPORTATION EXPENSES Special Conveyances Rental Automobiles § 301-10.451 May... Government includes full coverage insurance for damages resulting from an accident while performing official... cause extreme difficulty for an employee involved in an accident. ...
33 CFR 70.05-1 - General provisions.
Code of Federal Regulations, 2013 CFR
2013-07-01
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Code of Federal Regulations, 2011 CFR
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33 CFR 70.05-1 - General provisions.
Code of Federal Regulations, 2014 CFR
2014-07-01
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33 CFR 70.05-1 - General provisions.
Code of Federal Regulations, 2010 CFR
2010-07-01
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Code of Federal Regulations, 2010 CFR
2010-07-01
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NASA Astrophysics Data System (ADS)
McKenna, Alice
One of the functions of graphite is as a moderator in several nuclear reactor designs, including the Advanced Gas-cooled Reactor (AGR). In the reactor graphite is used to thermalise the neutrons produced in the fission reaction thus allowing a self-sustained reaction to occur. The graphite blocks, acting as the moderator, are constantly irradiated and consequently suffer damage. This thesis examines the types of damage caused using molecular dynamic (MD) simulations and ab intio calculations. Neutron damage starts with a primary knock-on atom (PKA), which is travelling so fast that it creates damage through electronic and thermal excitation (this is addressed with thermal spike simulations). When the PKA has lost energy the subsequent cascade is based on ballistic atomic displacement. These two types of simulations were performed on single crystal graphite and other carbon structures such as diamond and amorphous carbon as a comparison. The thermal spike in single crystal graphite produced results which varied from no defects to a small number of permanent defects in the structure. It is only at the high energy range that more damage is seen but these energies are less likely to occur in the nuclear reactor. The thermal spike does not create damage but it is possible that it can heal damaged sections of the graphite, which can be demonstrated with the motion of the defects when a thermal spike is applied. The cascade simulations create more damage than the thermal spike even though less energy is applied to the system. A new damage function is found with a threshold region that varies with the square root of energy in excess of the energy threshold. This is further broken down in to contributions from primary and subsequent knock-on atoms. The threshold displacement energy (TDE) is found to be Ed=25eV at 300K. In both these types of simulation graphite acts very differently to the other carbon structures. There are two types of polycrystalline graphite structures which simulations have been performed on. The difference between the two is at the grain boundaries with one having dangling bonds and the other one being bonded. The cascade showed the grain boundaries acting as a trap for the knock-on atoms which produces more damage compared with the single crystal. Finally the effects of turbostratic disorder on damage is considered. Density functional theory (DFT) was used to look at interstitials in (002) twist boundaries and how they act compared to AB stacked graphite. The results of these calculations show that the spiro interstitial is more stable in these grain boundaries, so at temperatures where the interstitial can migrate along the c direction they will segregate to (002) twist boundaries.
Radiation tolerance of nanocrystalline ceramics: insights from Yttria Stabilized Zirconia.
Dey, Sanchita; Drazin, John W; Wang, Yongqiang; Valdez, James A; Holesinger, Terry G; Uberuaga, Blas P; Castro, Ricardo H R
2015-01-13
Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr(+), 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.
Radiation Tolerance of Nanocrystalline Ceramics: Insights from Yttria Stabilized Zirconia
Dey, Sanchita; Drazin, John W.; Wang, Yongqiang; Valdez, James A.; Holesinger, Terry G.; Uberuaga, Blas P.; Castro, Ricardo H. R.
2015-01-01
Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr+, 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces. PMID:25582769
Radiation tolerance of nanocrystalline ceramics: Insights from yttria stabilized zirconia
Dey, Sanchita; Drazin, John W.; Wang, Yongqiang; ...
2015-01-13
Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr⁺, 400 keV) is inversely proportional to the grain size. HAADF imagesmore » suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.« less
Initial state with shear in peripheral heavy ion collisions
NASA Astrophysics Data System (ADS)
Magas, V. K.; Gordillo, J.; Strottman, D.; Xie, Y. L.; Csernai, L. P.
2018-06-01
In the present work we propose a new way of constructing the initial state for further hydrodynamic simulation of relativistic heavy ion collisions based on Bjorken-like solution applied streak by streak in the transverse plane. Previous fluid dynamical calculations in Cartesian coordinates with an initial state based on a streak by streak Yang-Mills field led for peripheral higher energy collisions to large angular momentum, initial shear flow and significant local vorticity. Recent experiments verified the existence of this vorticity via the resulting polarization of emitted Λ and Λ ¯ particles. At the same time parton cascade models indicated the existence of more compact initial state configurations, which we are going to simulate in our approach. The proposed model satisfies all the conservation laws, including conservation of a strong initial angular momentum, which is present in noncentral collisions. As a consequence of this large initial angular momentum we observe the rotation of the whole system as well as the fluid shear in the initial state, which leads to large flow vorticity. Another advantage of the proposed model is that the initial state can be given in both [t,x,y,z] and [τ ,x ,y ,η ] coordinates and thus can be tested by all 3+1D hydrodynamical codes which exist in the field.
Theory and modeling of atmospheric turbulence, part 1
NASA Technical Reports Server (NTRS)
1984-01-01
The cascade transfer which is the only function to describe the mode coupling as the result of the nonlinear hydrodynamic state of turbulence is discussed. A kinetic theory combined with a scaling procedure was developed. The transfer function governs the non-linear mode coupling in strong turbulence. The master equation is consistent with the hydrodynamical system that describes the microdynamic state of turbulence and has the advantages to be homogeneous and have fewer nonlinear terms. The modes are scaled into groups to decipher the governing transport processes and statistical characteristics. An equation of vorticity transport describes the microdynamic state of two dimensional, isotropic and homogeneous, geostrophic turbulence. The equation of evolution of the macrovorticity is derived from group scaling in the form of the Fokker-Planck equation with memory. The microdynamic state of turbulence is transformed into the Liouville equation to derive the kinetic equation of the singlet distribution in turbulence. The collision integral contains a memory, which is analyzed with pair collision and the multiple collision. Two other kinetic equations are developed in parallel for the propagator and the transition probability for the interaction among the groups.
Whiskers growth and self-healing in Ti-based metallic glasses during ion irradiation
NASA Astrophysics Data System (ADS)
Zhang, Kun; Hu, Zheng; Zhao, Ziqiang; Wei, Bingchen; Li, Yansen; Wei, Yuhang
2018-04-01
Ti-based metallic glasses were subjected to a 20 MeV Cl4+ ion radiation under liquid-nitrogen cooling. Their responses, as well as effects of the electronic excitation and nucleus-nucleus collision were evaluated. The collision cascade during irradiation typically changes the structure by increasing the liquid-like zone/cluster, or the content of the free volume. However, along the ion incident depth, the structure change is inhomogeneous. Numerous whiskers appear and aggregate on the side of the irradiation surface, which are several micrometers away from the edge. This corresponds with the maximum collision depth obtained by the Monte Carlo simulation, where nuclear loss plays a dominant role. Moreover, the liquid-like zone continually forms, which add to the whiskers growth and subsequent self-healing. Results suggest that the irradiation-induced local shear stress combines with the well-localized liquid-like zone results in the observed phenomena. This study demonstrates that metallic glasses have high morphological instability under ion irradiation, which assets can pave new paths for their further applications.
NASA Astrophysics Data System (ADS)
Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Alam, M. S.; Alam, M. A.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Andeen, T.; Anders, C. F.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonelli, S.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Aubert, B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Baltasar Dos Santos Pedrosa, F.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, D.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Battistoni, G.; Bauer, F.; Bawa, H. S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Behar Harpaz, S.; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ben Ami, S.; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bona, M.; Bondarenko, V. G.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Booth, P.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Brett, N. D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brubaker, E.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.; Buchanan, J.; Buchanan, N. J.; Buchholz, P.; Buckingham, R. M.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Budick, B.; Büscher, V.; Bugge, L.; Buira-Clark, D.; Buis, E. J.; Bulekov, O.; Bunse, M.; Buran, T.; Burckhart, H.; Burdin, S.; Burgess, T.; Burke, S.; Busato, E.; Bussey, P.; Buszello, C. P.; Butin, F.; Butler, B.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Buttinger, W.; Byatt, T.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Caloi, R.; Calvet, D.; Calvet, S.; Camacho Toro, R.; Camard, A.; Camarri, P.; Cambiaghi, M.; Cameron, D.; Cammin, J.; Campana, S.; Campanelli, M.; Canale, V.; Canelli, F.; Canepa, A.; Cantero, J.; Capasso, L.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capriotti, D.; Capua, M.; Caputo, R.; Caramarcu, C.; Cardarelli, R.; Carli, T.; Carlino, G.; Carminati, L.; Caron, B.; Caron, S.; Carpentieri, C.; Carrillo Montoya, G. D.; Carter, A. A.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Cascella, M.; Caso, C.; Castaneda Hernandez, A. M.; Castaneda-Miranda, E.; Castillo Gimenez, V.; Castro, N. F.; Cataldi, G.; Cataneo, F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Cattani, G.; Caughron, S.; Cauz, D.; Cavallari, A.; Cavalleri, P.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Cazzato, A.; Ceradini, F.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cetin, S. A.; Cevenini, F.; Chafaq, A.; Chakraborty, D.; Chan, K.; Chapleau, B.; Chapman, J. D.; Chapman, J. W.; Chareyre, E.; Charlton, D. G.; Chavda, V.; Cheatham, S.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, L.; Chen, S.; Chen, T.; Chen, X.; Cheng, S.; Cheplakov, A.; Chepurnov, V. F.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Cheung, S. L.; Chevalier, L.; Chiefari, G.; Chikovani, L.; Childers, J. T.; Chilingarov, A.; Chiodini, G.; Chizhov, M. V.; Choudalakis, G.; Chouridou, S.; Christidi, I. A.; Christov, A.; Chromek-Burckhart, D.; Chu, M. L.; Chudoba, J.; Ciapetti, G.; Ciba, K.; Ciftci, A. K.; Ciftci, R.; Cinca, D.; Cindro, V.; Ciobotaru, M. D.; Ciocca, C.; Ciocio, A.; Cirilli, M.; Ciubancan, M.; Clark, A.; Clark, P. J.; Cleland, W.; Clemens, J. C.; Clement, B.; Clement, C.; Clifft, R. W.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Coe, P.; Cogan, J. G.; Coggeshall, J.; Cogneras, E.; Cojocaru, C. D.; Colas, J.; Colijn, A. P.; Collard, C.; Collins, N. J.; Collins-Tooth, C.; Collot, J.; Colon, G.; Comune, G.; Conde Muiño, P.; Coniavitis, E.; Conidi, M. C.; Consonni, M.; Constantinescu, S.; Conta, C.; Conventi, F.; Cook, J.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cooper-Smith, N. J.; Copic, K.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Costin, T.; Côté, D.; Coura Torres, R.; Courneyea, L.; Cowan, G.; Cowden, C.; Cox, B. E.; Cranmer, K.; Crescioli, F.; Cristinziani, M.; Crosetti, G.; Crupi, R.; Crépé-Renaudin, S.; Cuenca Almenar, C.; Cuhadar Donszelmann, T.; Cuneo, S.; Curatolo, M.; Curtis, C. J.; Cwetanski, P.; Czirr, H.; Czyczula, Z.; D'Auria, S.; D'Onofrio, M.; D'Orazio, A.; da Rocha Gesualdi Mello, A.; da Silva, P. V. M.; da Via, C.; Dabrowski, W.; Dahlhoff, A.; Dai, T.; Dallapiccola, C.; Dallison, S. J.; Dam, M.; Dameri, M.; Damiani, D. S.; Danielsson, H. O.; Dankers, R.; Dannheim, D.; Dao, V.; Darbo, G.; Darlea, G. L.; Daum, C.; Dauvergne, J. P.; Davey, W.; Davidek, T.; Davidson, N.; Davidson, R.; Davies, M.; Davison, A. R.; Dawe, E.; Dawson, I.; Dawson, J. W.; Daya, R. K.; de, K.; de Asmundis, R.; de Castro, S.; de Castro Faria Salgado, P. E.; de Cecco, S.; de Graat, J.; de Groot, N.; de Jong, P.; de La Taille, C.; de la Torre, H.; de Lotto, B.; de Mora, L.; de Nooij, L.; de Oliveira Branco, M.; de Pedis, D.; de Saintignon, P.; de Salvo, A.; de Sanctis, U.; de Santo, A.; de Vivie de Regie, J. B.; Dean, S.; Dedovich, D. V.; Degenhardt, J.; Dehchar, M.; Deile, M.; Del Papa, C.; Del Peso, J.; Del Prete, T.; Dell'Acqua, A.; Dell'Asta, L.; Della Pietra, M.; Della Volpe, D.; Delmastro, M.; Delpierre, P.; Delruelle, N.; Delsart, P. A.; Deluca, C.; Demers, S.; Demichev, M.; Demirkoz, B.; Deng, J.; Denisov, S. P.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Devetak, E.; Deviveiros, P. O.; Dewhurst, A.; Dewilde, B.; Dhaliwal, S.; Dhullipudi, R.; di Ciaccio, A.; di Ciaccio, L.; di Girolamo, A.; di Girolamo, B.; di Luise, S.; di Mattia, A.; di Micco, B.; di Nardo, R.; di Simone, A.; di Sipio, R.; Diaz, M. A.; Diblen, F.; Diehl, E. B.; Dietl, H.; Dietrich, J.; Dietzsch, T. A.; Diglio, S.; Dindar Yagci, K.; Dingfelder, J.; Dionisi, C.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djilkibaev, R.; Djobava, T.; Do Vale, M. A. B.; Do Valle Wemans, A.; Doan, T. K. O.; Dobbs, M.; Dobinson, R.; Dobos, D.; Dobson, E.; Dobson, M.; Dodd, J.; Dogan, O. B.; Doglioni, C.; Doherty, T.; Doi, Y.; Dolejsi, J.; Dolenc, I.; Dolezal, Z.; Dolgoshein, B. A.; Dohmae, T.; Donadelli, M.; Donega, M.; Donini, J.; Dopke, J.; Doria, A.; Dos Anjos, A.; Dosil, M.; Dotti, A.; Dova, M. T.; Dowell, J. D.; Doxiadis, A. D.; Doyle, A. T.; Drasal, Z.; Drees, J.; Dressnandt, N.; Drevermann, H.; Driouichi, C.; Dris, M.; Drohan, J. G.; Dubbert, J.; Dubbs, T.; Dube, S.; Duchovni, E.; Duckeck, G.; Dudarev, A.; Dudziak, F.; Dührssen, M.; Duerdoth, I. P.; Duflot, L.; Dufour, M.-A.; Dunford, M.; Duran Yildiz, H.; Duxfield, R.; Dwuznik, M.; Dydak, F.; Dzahini, D.; Düren, M.; Ebenstein, W. L.; Ebke, J.; Eckert, S.; Eckweiler, S.; Edmonds, K.; Edwards, C. A.; Ehrenfeld, W.; Ehrich, T.; Eifert, T.; Eigen, G.; Einsweiler, K.; Eisenhandler, E.; Ekelof, T.; El Kacimi, M.; Ellert, M.; Elles, S.; Ellinghaus, F.; Ellis, K.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Ely, R.; Emeliyanov, D.; Engelmann, R.; Engl, A.; Epp, B.; Eppig, A.; Erdmann, J.; Ereditato, A.; Eriksson, D.; Ernst, J.; Ernst, M.; Ernwein, J.; Errede, D.; Errede, S.; Ertel, E.; Escalier, M.; Escobar, C.; Espinal Curull, X.; Esposito, B.; Etienne, F.; Etienvre, A. I.; Etzion, E.; Evangelakou, D.; Evans, H.; Fabbri, L.; Fabre, C.; Facius, K.; Fakhrutdinov, R. M.; Falciano, S.; Falou, A. C.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farley, J.; Farooque, T.; Farrington, S. M.; Farthouat, P.; Fasching, D.; Fassnacht, P.; Fassouliotis, D.; Fatholahzadeh, B.; Favareto, A.; Fayard, L.; Fazio, S.; Febbraro, R.; Federic, P.; Fedin, O. L.; Fedorko, I.; Fedorko, W.; Fehling-Kaschek, M.; Feligioni, L.; Fellmann, D.; Felzmann, C. U.; Feng, C.; Feng, E. J.; Fenyuk, A. B.; Ferencei, J.; Ferland, J.; Fernandes, B.; Fernando, W.; Ferrag, S.; Ferrando, J.; Ferrara, V.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferrer, A.; Ferrer, M. L.; Ferrere, D.; Ferretti, C.; Ferretto Parodi, A.; Fiascaris, M.; Fiedler, F.; Filipčič, A.; Filippas, A.; Filthaut, F.; Fincke-Keeler, M.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, G.; Fischer, P.; Fisher, M. J.; Fisher, S. M.; Flammer, J.; Flechl, M.; Fleck, I.; Fleckner, J.; Fleischmann, P.; Fleischmann, S.; Flick, T.; Flores Castillo, L. R.; Flowerdew, M. J.; Föhlisch, F.; Fokitis, M.; Fonseca Martin, T.; Forbush, D. A.; Formica, A.; Forti, A.; Fortin, D.; Foster, J. M.; Fournier, D.; Foussat, A.; Fowler, A. J.; Fowler, K.; Fox, H.; Francavilla, P.; Franchino, S.; Francis, D.; Frank, T.; Franklin, M.; Franz, S.; Fraternali, M.; Fratina, S.; French, S. T.; Froeschl, R.; Froidevaux, D.; Frost, J. 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F.; Mora Herrera, C.; Moraes, A.; Morais, A.; Morange, N.; Morello, G.; Moreno, D.; Moreno Llácer, M.; Morettini, P.; Morii, M.; Morin, J.; Morita, Y.; Morley, A. K.; Mornacchi, G.; Morone, M.-C.; Morozov, S. V.; Morris, J. D.; Moser, H. G.; Mosidze, M.; Moss, J.; Mount, R.; Mountricha, E.; Mouraviev, S. V.; Moyse, E. J. W.; Mudrinic, M.; Mueller, F.; Mueller, J.; Mueller, K.; Müller, T. A.; Muenstermann, D.; Muijs, A.; Muir, A.; Munwes, Y.; Murakami, K.; Murray, W. J.; Mussche, I.; Musto, E.; Myagkov, A. G.; Myska, M.; Nadal, J.; Nagai, K.; Nagano, K.; Nagasaka, Y.; Nairz, A. M.; Nakahama, Y.; Nakamura, K.; Nakano, I.; Nanava, G.; Napier, A.; Nash, M.; Nation, N. R.; Nattermann, T.; Naumann, T.; Navarro, G.; Neal, H. A.; Nebot, E.; Nechaeva, P. Yu.; Negri, A.; Negri, G.; Nektarijevic, S.; Nelson, A.; Nelson, S.; Nelson, T. K.; Nemecek, S.; Nemethy, P.; Nepomuceno, A. A.; Nessi, M.; Nesterov, S. Y.; Neubauer, M. S.; Neusiedl, A.; Neves, R. M.; Nevski, P.; Newman, P. R.; Nickerson, R. B.; Nicolaidou, R.; Nicolas, L.; Nicquevert, B.; Niedercorn, F.; Nielsen, J.; Niinikoski, T.; Nikiforov, A.; Nikolaenko, V.; Nikolaev, K.; Nikolic-Audit, I.; Nikolopoulos, K.; Nilsen, H.; Nilsson, P.; Ninomiya, Y.; Nisati, A.; Nishiyama, T.; Nisius, R.; Nodulman, L.; Nomachi, M.; Nomidis, I.; Nomoto, H.; Nordberg, M.; Nordkvist, B.; Norton, P. R.; Novakova, J.; Nozaki, M.; Nožička, M.; Nozka, L.; Nugent, I. M.; Nuncio-Quiroz, A.-E.; Nunes Hanninger, G.; Nunnemann, T.; Nurse, E.; Nyman, T.; O'Brien, B. J.; O'Neale, S. W.; O'Neil, D. C.; O'Shea, V.; Oakham, F. G.; Oberlack, H.; Ocariz, J.; Ochi, A.; Oda, S.; Odaka, S.; Odier, J.; Ogren, H.; Oh, A.; Oh, S. H.; Ohm, C. C.; Ohshima, T.; Ohshita, H.; Ohska, T. K.; Ohsugi, T.; Okada, S.; Okawa, H.; Okumura, Y.; Okuyama, T.; Olcese, M.; Olchevski, A. G.; Oliveira, M.; Oliveira Damazio, D.; Oliver Garcia, E.; Olivito, D.; Olszewski, A.; Olszowska, J.; Omachi, C.; Onofre, A.; Onyisi, P. U. E.; Oram, C. J.; Oreglia, M. J.; Orellana, F.; Oren, Y.; Orestano, D.; Orlov, I.; Oropeza Barrera, C.; Orr, R. S.; Ortega, E. O.; Osculati, B.; Ospanov, R.; Osuna, C.; Otero Y Garzon, G.; Ottersbach, J. P.; Ouchrif, M.; Ould-Saada, F.; Ouraou, A.; Ouyang, Q.; Owen, M.; Owen, S.; Øye, O. K.; Ozcan, V. E.; Ozturk, N.; Pacheco Pages, A.; Padilla Aranda, C.; Paganis, E.; Paige, F.; Pajchel, K.; Palestini, S.; Pallin, D.; Palma, A.; Palmer, J. D.; Pan, Y. B.; Panagiotopoulou, E.; Panes, B.; Panikashvili, N.; Panitkin, S.; Pantea, D.; Panuskova, M.; Paolone, V.; Paoloni, A.; Papadelis, A.; Papadopoulou, Th. D.; Paramonov, A.; Park, W.; Parker, M. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pasqualucci, E.; Passeri, A.; Pastore, F.; Pastore, Fr.; Pásztor, G.; Pataraia, S.; Patel, N.; Pater, J. R.; Patricelli, S.; Pauly, T.; Pecsy, M.; Pedraza Morales, M. I.; Peleganchuk, S. V.; Peng, H.; Pengo, R.; Penson, A.; Penwell, J.; Perantoni, M.; Perez, K.; Perez Cavalcanti, T.; Perez Codina, E.; Pérez García-Estañ, M. T.; Perez Reale, V.; Peric, I.; Perini, L.; Pernegger, H.; Perrino, R.; Perrodo, P.; Persembe, S.; Peshekhonov, V. D.; Peters, O.; Petersen, B. A.; Petersen, J.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petrolo, E.; Petrucci, F.; Petschull, D.; Petteni, M.; Pezoa, R.; Phan, A.; Phillips, A. W.; Phillips, P. W.; Piacquadio, G.; Piccaro, E.; Piccinini, M.; Pickford, A.; Piec, S. M.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pina, J.; Pinamonti, M.; Pinder, A.; Pinfold, J. L.; Ping, J.; Pinto, B.; Pirotte, O.; Pizio, C.; Placakyte, R.; Plamondon, M.; Plano, W. G.; Pleier, M.-A.; Pleskach, A. V.; Poblaguev, A.; Poddar, S.; Podlyski, F.; Poggioli, L.; Poghosyan, T.; Pohl, M.; Polci, F.; Polesello, G.; Policicchio, A.; Polini, A.; Poll, J.; Polychronakos, V.; Pomarede, D. M.; Pomeroy, D.; Pommès, K.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Popovic, D. S.; Poppleton, A.; Portell Bueso, X.; Porter, R.; Posch, C.; Pospelov, G. E.; Pospisil, S.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Poulard, G.; Poveda, J.; Prabhu, R.; Pralavorio, P.; Prasad, S.; Pravahan, R.; Prell, S.; Pretzl, K.; Pribyl, L.; Price, D.; Price, L. E.; Price, M. J.; Prichard, P. M.; Prieur, D.; Primavera, M.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Prudent, X.; Przysiezniak, H.; Psoroulas, S.; Ptacek, E.; Purdham, J.; Purohit, M.; Puzo, P.; Pylypchenko, Y.; Qian, J.; Qian, Z.; Qin, Z.; Quadt, A.; Quarrie, D. R.; Quayle, W. B.; Quinonez, F.; Raas, M.; Radescu, V.; Radics, B.; Rador, T.; Ragusa, F.; Rahal, G.; Rahimi, A. M.; Rahm, D.; Rajagopalan, S.; Rammensee, M.; Rammes, M.; Ramstedt, M.; Randrianarivony, K.; Ratoff, P. N.; Rauscher, F.; Rauter, E.; Raymond, M.; Read, A. L.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reeves, K.; Reichold, A.; Reinherz-Aronis, E.; Reinsch, A.; Reisinger, I.; Reljic, D.; Rembser, C.; Ren, Z. L.; Renaud, A.; Renkel, P.; Rensch, B.; Rescigno, M.; Resconi, S.; Resende, B.; Reznicek, P.; Rezvani, R.; Richards, A.; Richter, R.; Richter-Was, E.; Ridel, M.; Rieke, S.; Rijpstra, M.; Rijssenbeek, M.; Rimoldi, A.; Rinaldi, L.; Rios, R. R.; Riu, I.; Rivoltella, G.; Rizatdinova, F.; Rizvi, E.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robinson, M.; Robson, A.; Rocha de Lima, J. G.; Roda, C.; Roda Dos Santos, D.; Rodier, S.; Rodriguez, D.; Rodriguez Garcia, Y.; Roe, A.; Roe, S.; Røhne, O.; Rojo, V.; Rolli, S.; Romaniouk, A.; Romanov, V. M.; Romeo, G.; Romero Maltrana, D.; Roos, L.; Ros, E.; Rosati, S.; Rose, M.; Rosenbaum, G. A.; Rosenberg, E. I.; Rosendahl, P. L.; Rosselet, L.; Rossetti, V.; Rossi, E.; Rossi, L. P.; Rossi, L.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Royon, C. R.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubinskiy, I.; Ruckert, B.; Ruckstuhl, N.; Rud, V. I.; Rudolph, G.; Rühr, F.; Ruggieri, F.; Ruiz-Martinez, A.; Rulikowska-Zarebska, E.; Rumiantsev, V.; Rumyantsev, L.; Runge, K.; Runolfsson, O.; Rurikova, Z.; Rusakovich, N. A.; Rust, D. R.; Rutherfoord, J. P.; Ruwiedel, C.; Ruzicka, P.; Ryabov, Y. F.; Ryadovikov, V.; Ryan, P.; Rybar, M.; Rybkin, G.; Ryder, N. C.; Rzaeva, S.; Saavedra, A. F.; Sadeh, I.; Sadrozinski, H. F.-W.; Sadykov, R.; Safai Tehrani, F.; Sakamoto, H.; Salamanna, G.; Salamon, A.; Saleem, M.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvachua Ferrando, B. M.; Salvatore, D.; Salvatore, F.; Salzburger, A.; Sampsonidis, D.; Samset, B. H.; Sandaker, H.; Sander, H. G.; Sanders, M. P.; Sandhoff, M.; Sandhu, P.; Sandoval, T.; Sandstroem, R.; Sandvoss, S.; Sankey, D. P. C.; Sansoni, A.; Santamarina Rios, C.; Santoni, C.; Santonico, R.; Santos, H.; Saraiva, J. G.; Sarangi, T.; Sarkisyan-Grinbaum, E.; Sarri, F.; Sartisohn, G.; Sasaki, O.; Sasaki, T.; Sasao, N.; Satsounkevitch, I.; Sauvage, G.; Sauvan, J. B.; Savard, P.; Savinov, V.; Savu, D. O.; Savva, P.; Sawyer, L.; Saxon, D. H.; Says, L. P.; Sbarra, C.; Sbrizzi, A.; Scallon, O.; Scannicchio, D. A.; Schaarschmidt, J.; Schacht, P.; Schäfer, U.; Schaepe, S.; Schaetzel, S.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Schamov, A. G.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Scherzer, M. I.; Schiavi, C.; Schieck, J.; Schioppa, M.; Schlenker, S.; Schlereth, J. L.; Schmidt, E.; Schmidt, M. P.; Schmieden, K.; Schmitt, C.; Schmitz, M.; Schöning, A.; Schott, M.; Schouten, D.; Schovancova, J.; Schram, M.; Schroeder, C.; Schroer, N.; Schuh, S.; Schuler, G.; Schultes, J.; Schultz-Coulon, H.-C.; Schulz, H.; Schumacher, J. W.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwanenberger, C.; Schwartzman, A.; Schwemling, Ph.; Schwienhorst, R.; Schwierz, R.; Schwindling, J.; Scott, W. G.; Searcy, J.; Sedykh, E.; Segura, E.; Seidel, S. C.; Seiden, A.; Seifert, F.; Seixas, J. M.; Sekhniaidze, G.; Seliverstov, D. M.; Sellden, B.; Sellers, G.; Seman, M.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Seuster, R.; Severini, H.; Sevior, M. E.; Sfyrla, A.; Shabalina, E.; Shamim, M.; Shan, L. Y.; Shank, J. T.; Shao, Q. T.; Shapiro, M.; Shatalov, P. B.; Shaver, L.; Shaw, C.; Shaw, K.; Sherman, D.; Sherwood, P.; Shibata, A.; Shimizu, S.; Shimojima, M.; Shin, T.; Shmeleva, A.; Shochet, M. J.; Short, D.; Shupe, M. A.; Sicho, P.; Sidoti, A.; Siebel, A.; Siegert, F.; Siegrist, J.; Sijacki, Dj.; Silbert, O.; Silva, J.; Silver, Y.; Silverstein, D.; Silverstein, S. B.; Simak, V.; Simard, O.; Simic, Lj.; Simion, S.; Simmons, B.; Simonyan, M.; Sinervo, P.; Sinev, N. B.; Sipica, V.; Siragusa, G.; Sisakyan, A. N.; Sivoklokov, S. Yu.; Sjölin, J.; Sjursen, T. B.; Skinnari, L. A.; Skovpen, K.; Skubic, P.; Skvorodnev, N.; Slater, M.; Slavicek, T.; Sliwa, K.; Sloan, T. J.; Sloper, J.; Smakhtin, V.; Smirnov, S. Yu.; Smirnova, L. N.; Smirnova, O.; Smith, B. C.; Smith, D.; Smith, K. M.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snow, S. W.; Snow, J.; Snuverink, J.; Snyder, S.; Soares, M.; Sobie, R.; Sodomka, J.; Soffer, A.; Solans, C. A.; Solar, M.; Solc, J.; Soldatov, E.; Soldevila, U.; Solfaroli Camillocci, E.; Solodkov, A. A.; Solovyanov, O. V.; Sondericker, J.; Soni, N.; Sopko, V.; Sopko, B.; Sorbi, M.; Sosebee, M.; Soukharev, A.; Spagnolo, S.; Spanò, F.; Spighi, R.; Spigo, G.; Spila, F.; Spiriti, E.; Spiwoks, R.; Spousta, M.; Spreitzer, T.; Spurlock, B.; Denis, R. D. St.; Stahl, T.; Stahlman, J.; Stamen, R.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stapnes, S.; Starchenko, E. A.; Stark, J.; Staroba, P.; Starovoitov, P.; Staude, A.; Stavina, P.; Stavropoulos, G.; Steele, G.; Steinbach, P.; Steinberg, P.; Stekl, I.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stevenson, K.; Stewart, G. A.; Stillings, J. A.; Stockmanns, T.; Stockton, M. C.; Stoerig, K.; Stoicea, G.; Stonjek, S.; Strachota, P.; Stradling, A. R.; Straessner, A.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strang, M.; Strauss, E.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Strong, J. A.; Stroynowski, R.; Strube, J.; Stugu, B.; Stumer, I.; Stupak, J.; Sturm, P.; Soh, D. A.; Su, D.; Subramania, H. S.; Succurro, A.; Sugaya, Y.; Sugimoto, T.; Suhr, C.; Suita, K.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Sushkov, S.; Susinno, G.; Sutton, M. R.; Suzuki, Y.; Sviridov, Yu. M.; Swedish, S.; Sykora, I.; Sykora, T.; Szeless, B.; Sánchez, J.; Ta, D.; Tackmann, K.; Taffard, A.; Tafirout, R.; Taga, A.; Taiblum, N.; Takahashi, Y.; Takai, H.; Takashima, R.; Takeda, H.; Takeshita, T.; Talby, M.; Talyshev, A.; Tamsett, M. C.; Tanaka, J.; Tanaka, R.; Tanaka, S.; Tanaka, S.; Tanaka, Y.; Tani, K.; Tannoury, N.; Tappern, G. P.; Tapprogge, S.; Tardif, D.; Tarem, S.; Tarrade, F.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tassi, E.; Tatarkhanov, M.; Taylor, C.; Taylor, F. E.; Taylor, G. N.; Taylor, W.; Teixeira Dias Castanheira, M.; Teixeira-Dias, P.; Temming, K. K.; Ten Kate, H.; Teng, P. K.; Terada, S.; Terashi, K.; Terron, J.; Terwort, M.; Testa, M.; Teuscher, R. J.; Tevlin, C. M.; Thadome, J.; Therhaag, J.; Theveneaux-Pelzer, T.; Thioye, M.; Thoma, S.; Thomas, J. P.; Thompson, E. N.; Thompson, P. D.; Thompson, P. D.; Thompson, A. S.; Thomson, E.; Thomson, M.; Thun, R. P.; Tic, T.; Tikhomirov, V. O.; Tikhonov, Y. A.; Timmermans, C. J. W. P.; Tipton, P.; Tique Aires Viegas, F. J.; Tisserant, S.; Tobias, J.; Toczek, B.; Todorov, T.; Todorova-Nova, S.; Toggerson, B.; Tojo, J.; Tokár, S.; Tokunaga, K.; Tokushuku, K.; Tollefson, K.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, G.; Tonoyan, A.; Topfel, C.; Topilin, N. D.; Torchiani, I.; Torrence, E.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Traynor, D.; Trefzger, T.; Treis, J.; Tremblet, L.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Trinh, T. N.; Tripiana, M. F.; Triplett, N.; Trischuk, W.; Trivedi, A.; Trocmé, B.; Troncon, C.; Trottier-McDonald, M.; Trzupek, A.; Tsarouchas, C.; Tseng, J. C.-L.; Tsiakiris, M.; Tsiareshka, P. V.; Tsionou, D.; Tsipolitis, G.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsukerman, I. I.; Tsulaia, V.; Tsung, J.-W.; Tsuno, S.; Tsybychev, D.; Tua, A.; Tuggle, J. M.; Turala, M.; Turecek, D.; Turk Cakir, I.; Turlay, E.; Turra, R.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Tyrvainen, H.; Tzanakos, G.; Uchida, K.; Ueda, I.; Ueno, R.; Ugland, M.; Uhlenbrock, M.; Uhrmacher, M.; Ukegawa, F.; Unal, G.; Underwood, D. G.; Undrus, A.; Unel, G.; Unno, Y.; Urbaniec, D.; Urkovsky, E.; Urrejola, P.; Usai, G.; Uslenghi, M.; Vacavant, L.; Vacek, V.; Vachon, B.; Vahsen, S.; Valderanis, C.; Valenta, J.; Valente, P.; Valentinetti, S.; Valkar, S.; Valladolid Gallego, E.; Vallecorsa, S.; Valls Ferrer, J. A.; van der Graaf, H.; van der Kraaij, E.; van der Leeuw, R.; van der Poel, E.; van der Ster, D.; van Eijk, B.; van Eldik, N.; van Gemmeren, P.; van Kesteren, Z.; van Vulpen, I.; Vandelli, W.; Vandoni, G.; Vaniachine, A.; Vankov, P.; Vannucci, F.; Varela Rodriguez, F.; Vari, R.; Varnes, E. W.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vassilakopoulos, V. I.; Vazeille, F.; Vegni, G.; Veillet, J. J.; Vellidis, C.; Veloso, F.; Veness, R.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Vichou, I.; Vickey, T.; Viehhauser, G. H. A.; Viel, S.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinek, E.; Vinogradov, V. B.; Virchaux, M.; Viret, S.; Virzi, J.; Vitale, A.; Vitells, O.; Viti, M.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vlasak, M.; Vlasov, N.; Vogel, A.; Vokac, P.; Volpi, G.; Volpi, M.; Volpini, G.; von der Schmitt, H.; von Loeben, J.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobiev, A. P.; Vorwerk, V.; Vos, M.; Voss, R.; Voss, T. T.; Vossebeld, J. H.; Vovenko, A. S.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vu Anh, T.; Vuillermet, R.; Vukotic, I.; Wagner, W.; Wagner, P.; Wahlen, H.; Wakabayashi, J.; Walbersloh, J.; Walch, S.; Walder, J.; Walker, R.; Walkowiak, W.; Wall, R.; Waller, P.; Wang, C.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, J. C.; Wang, R.; Wang, S. M.; Warburton, A.; Ward, C. P.; Warsinsky, M.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, A. T.; Waugh, B. M.; Weber, J.; Weber, M.; Weber, M. S.; Weber, P.; Weidberg, A. R.; Weigell, P.; Weingarten, J.; Weiser, C.; Wellenstein, H.; Wells, P. S.; Wen, M.; Wenaus, T.; Wendler, S.; Weng, Z.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Werth, M.; Wessels, M.; Whalen, K.; Wheeler-Ellis, S. J.; Whitaker, S. P.; White, A.; White, M. J.; White, S.; Whitehead, S. R.; Whiteson, D.; Whittington, D.; Wicek, F.; Wicke, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik, L. A. M.; Wijeratne, P. A.; Wildauer, A.; Wildt, M. A.; Wilhelm, I.; Wilkens, H. G.; Will, J. Z.; Williams, E.; Williams, H. H.; Willis, W.; Willocq, S.; Wilson, J. A.; Wilson, M. G.; Wilson, A.; Wingerter-Seez, I.; Winkelmann, S.; Winklmeier, F.; Wittgen, M.; Wolter, M. W.; Wolters, H.; Wooden, G.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wraight, K.; Wright, C.; Wrona, B.; Wu, S. L.; Wu, X.; Wu, Y.; Wulf, E.; Wunstorf, R.; Wynne, B. M.; Xaplanteris, L.; Xella, S.; Xie, S.; Xie, Y.; Xu, C.; Xu, D.; Xu, G.; Yabsley, B.; Yamada, M.; Yamamoto, A.; Yamamoto, K.; Yamamoto, S.; Yamamura, T.; Yamanaka, T.; Yamaoka, J.; Yamazaki, T.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, U. K.; Yang, Y.; Yang, Y.; Yang, Z.; Yanush, S.; Yao, W.-M.; Yao, Y.; Yasu, Y.; Ybeles Smit, G. V.; Ye, J.; Ye, S.; Yilmaz, M.; Yoosoofmiya, R.; Yorita, K.; Yoshida, R.; Young, C.; Youssef, S.; Yu, D.; Yu, J.; Yu, J.; Yuan, L.; Yurkewicz, A.; Zaets, V. G.; Zaidan, R.; Zaitsev, A. M.; Zajacova, Z.; Zalite, Yo. K.; Zanello, L.; Zarzhitsky, P.; Zaytsev, A.; Zeitnitz, C.; Zeller, M.; Zema, P. F.; Zemla, A.; Zendler, C.; Zenin, A. V.; Zenin, O.; Ženiš, T.; Zenonos, Z.; Zenz, S.; Zerwas, D.; Zevi Della Porta, G.; Zhan, Z.; Zhang, D.; Zhang, H.; Zhang, J.; Zhang, X.; Zhang, Z.; Zhao, L.; Zhao, T.; Zhao, Z.; Zhemchugov, A.; Zheng, S.; Zhong, J.; Zhou, B.; Zhou, N.; Zhou, Y.; Zhu, C. G.; Zhu, H.; Zhu, Y.; Zhuang, X.; Zhuravlov, V.; Zieminska, D.; Zimmermann, R.; Zimmermann, S.; Zimmermann, S.; Ziolkowski, M.; Zitoun, R.; Živković, L.; Zmouchko, V. V.; Zobernig, G.; Zoccoli, A.; Zolnierowski, Y.; Zsenei, A.; Zur Nedden, M.; Zutshi, V.; Zwalinski, L.; Atlas Collaboration
2011-07-01
Results are presented of a search for supersymmetric particles in events with large missing transverse momentum and at least one heavy flavour jet candidate in √{ s} = 7 TeV proton-proton collisions. In a data sample corresponding to an integrated luminosity of 35 pb-1 recorded by the ATLAS experiment at the Large Hadron Collider, no significant excess is observed with respect to the prediction for Standard Model processes. For R-parity conserving models in which sbottoms (stops) are the only squarks to appear in the gluino decay cascade, gluino masses below 590 GeV (520 GeV) are excluded at the 95% C.L. The results are also interpreted in an MSUGRA/CMSSM supersymmetry breaking scenario with tan β = 40 and in an SO(10) model framework.
Accumulation of dislocation loops in the α phase of Zr Excel alloy under heavy ion irradiation
NASA Astrophysics Data System (ADS)
Yu, Hongbing; Yao, Zhongwen; Idrees, Yasir; Zhang, He K.; Kirk, Mark A.; Daymond, Mark R.
2017-08-01
In-situ heavy ion irradiations were performed on the high Sn content Zr alloy 'Excel', measuring type dislocation loop accumulation up to irradiation damage doses of 10 dpa at a range of temperatures. The high content of Sn, which diffuses slowly, and the thin foil geometry of the sample provide a unique opportunity to study an extreme case where displacement cascades dominate the loop formation and evolution. The dynamic observation of dislocation loop evolution under irradiation at 200 °C reveals that type dislocation loops can form at very low dose (0.0025 dpa). The size of the dislocation loops increases slightly with irradiation damage dose. The mechanism controlling loop growth in this study is different from that in neutron irradiation; in this study, larger dislocation loops can condense directly from the interaction of displacement cascades and the high concentration of point defects in the matrix. The size of the dislocation loop is dependent on the point defect concentration in the matrix. A negative correlation between the irradiation temperature and the dislocation loop size was observed. A comparison between cascade dominated loop evolution (this study), diffusion dominated loop evolution (electron irradiation) and neutron irradiation suggests that heavy ion irradiation alone may not be enough to accurately reproduce neutron irradiation induced loop structures. An alternative method is proposed in this paper. The effects of Sn on the displacement cascades, defect yield, and the diffusion behavior of point defects are established.
Electrondriven processes in polyatomic molecules
DOE Office of Scientific and Technical Information (OSTI.GOV)
McKoy, Vincent
2017-03-20
This project developed and applied scalable computational methods to obtain information about low-energy electron collisions with larger polyatomic molecules. Such collisions are important in modeling radiation damage to living systems, in spark ignition and combustion, and in plasma processing of materials. The focus of the project was to develop efficient methods that could be used to obtain both fundamental scientific insights and data of practical value to applications.
Displacement damage and predicted non-ionizing energy loss in GaAs
NASA Astrophysics Data System (ADS)
Gao, Fei; Chen, Nanjun; Hernandez-Rivera, Efrain; Huang, Danhong; LeVan, Paul D.
2017-03-01
Large-scale molecular dynamics (MD) simulations, along with bond-order interatomic potentials, have been applied to study the defect production for lattice atom recoil energies from 500 eV to 20 keV in gallium arsenide (GaAs). At low energies, the most surviving defects are single interstitials and vacancies, and only 20% of the interstitial population is contained in clusters. However, a direct-impact amorphization in GaAs occurs with a high degree of probability during the cascade lifetime for Ga PKAs (primary knock-on atoms) with energies larger than 2 keV. The results reveal a non-linear defect production that increases with the PKA energy. The damage density within a cascade core is evaluated, and used to develop a model that describes a new energy partition function. Based on the MD results, we have developed a model to determine the non-ionizing energy loss (NIEL) in GaAs, which can be used to predict the displacement damage degradation induced by space radiation on electronic components. The calculated NIEL predictions are compared with the available data, thus validating the NIEL model developed in this study.
Optimization of cascading failure on complex network based on NNIA
NASA Astrophysics Data System (ADS)
Zhu, Qian; Zhu, Zhiliang; Qi, Yi; Yu, Hai; Xu, Yanjie
2018-07-01
Recently, the robustness of networks under cascading failure has attracted extensive attention. Different from previous studies, we concentrate on how to improve the robustness of the networks from the perspective of intelligent optimization. We establish two multi-objective optimization models that comprehensively consider the operational cost of the edges in the networks and the robustness of the networks. The NNIA (Non-dominated Neighbor Immune Algorithm) is applied to solve the optimization models. We finished simulations of the Barabási-Albert (BA) network and Erdös-Rényi (ER) network. In the solutions, we find the edges that can facilitate the propagation of cascading failure and the edges that can suppress the propagation of cascading failure. From the conclusions, we take optimal protection measures to weaken the damage caused by cascading failures. We also consider actual situations of operational cost feasibility of the edges. People can make a more practical choice based on the operational cost. Our work will be helpful in the design of highly robust networks or improvement of the robustness of networks in the future.
NASA Astrophysics Data System (ADS)
Wang, Zhenhua; Li, Qingyun; Huang, Zhuo; Tang, Xianqiang; Zhao, Weihua
2017-05-01
Cascaded exploitation of diversion-type small hydropower (SHP) offers a source of new energy as well as socioeconomic benefits; however, it inevitably causes environmental disturbance and damage. Previous studies on the cumulative effect of cascaded diversion SHP rarely discussed using quantitative analysis method. In this paper, the ecological footprint analysis approach is proposed to assess the positive and negative impacts of cascaded diversion SHP on environment of a small-scale river in Southwest China. Positive impact is defined as ecological supply footprint (ESF), which refers to vegetation protection by replacing firewood with SHP. Negative impact is defined as ecological loss footprint (ELF), which includes fish and net primary productivity loss, vegetation destruction and soil erosion. With the raising in the number (n>4) of diversion SHP stations, the difference between ELF and ESF increases remarkably, suggesting that the adverse impacts of cascaded diversion SHP accumulate in the study area. Compared with vegetation destruction and soil erosion, the cumulative loss of fish and net productivity is the most important aspect of the adverse impacts which needs more attentions.
Development of relativistic shock waves in viscous gluon matter
NASA Astrophysics Data System (ADS)
Bouras, I.; Molnár, E.; Niemi, H.; Xu, Z.; El, A.; Fochler, O.; Greiner, C.; Rischke, D. H.
2009-11-01
To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio η/s. We show that an η/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. These findings are confirmed by viscous hydrodynamic calculations.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Smith, R.; Harrison, D. E. Jr.
A variable time step integration algorithm for carrying out molecular dynamics simulations of atomic collision cascades is proposed which evaluates the interaction forces only once per time step. The algorithm is tested on some model problems which have exact solutions and is compared against other common methods. These comparisons show that the method has good stability and accuracy. Applications to Ar/sup +/ bombardment of Cu and Si show good accuracy and improved speed to the original method (D. E. Harrison, W. L. Gay, and H. M. Effron, J. Math. Phys. /bold 10/, 1179 (1969)).
NASA Astrophysics Data System (ADS)
Kalmykov, N. N.; Ostapchenko, S. S.; Werner, K.
An extensive air shower (EAS) calculation scheme based on cascade equations and some EAS characteristics for energies 1014 -1017 eV are presented. The universal hadronic interaction model NEXUS is employed to provide the necessary data concerning hadron-air collisions. The influence of model assumptions on the longitudinal EAS development is discussed in the framework of the NEXUS and QGSJET models. Applied to EAS simulations, perspectives of combined Monte Carlo and numerical methods are considered.
5 CFR 180.104 - Allowable claims.
Code of Federal Regulations, 2011 CFR
2011-01-01
... mobile homes may be allowed only in cases of collision, theft, or vandalism. (5) Money. Claims for money... claimant's supervisor. (4) Mobile homes. Claims may be allowed for damage to or loss of mobile homes and their contents under the provisions of § 180.104(c)(2). Claims for structural damage to mobile homes...
5 CFR 180.104 - Allowable claims.
Code of Federal Regulations, 2012 CFR
2012-01-01
... mobile homes may be allowed only in cases of collision, theft, or vandalism. (5) Money. Claims for money... claimant's supervisor. (4) Mobile homes. Claims may be allowed for damage to or loss of mobile homes and their contents under the provisions of § 180.104(c)(2). Claims for structural damage to mobile homes...
5 CFR 180.104 - Allowable claims.
Code of Federal Regulations, 2014 CFR
2014-01-01
... mobile homes may be allowed only in cases of collision, theft, or vandalism. (5) Money. Claims for money... claimant's supervisor. (4) Mobile homes. Claims may be allowed for damage to or loss of mobile homes and their contents under the provisions of § 180.104(c)(2). Claims for structural damage to mobile homes...
5 CFR 180.104 - Allowable claims.
Code of Federal Regulations, 2010 CFR
2010-01-01
... mobile homes may be allowed only in cases of collision, theft, or vandalism. (5) Money. Claims for money... claimant's supervisor. (4) Mobile homes. Claims may be allowed for damage to or loss of mobile homes and their contents under the provisions of § 180.104(c)(2). Claims for structural damage to mobile homes...
5 CFR 180.104 - Allowable claims.
Code of Federal Regulations, 2013 CFR
2013-01-01
... mobile homes may be allowed only in cases of collision, theft, or vandalism. (5) Money. Claims for money... claimant's supervisor. (4) Mobile homes. Claims may be allowed for damage to or loss of mobile homes and their contents under the provisions of § 180.104(c)(2). Claims for structural damage to mobile homes...
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Penalty. 70.05-5 Section 70.05-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation § 70.05-5 Penalty...
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Penalty. 70.05-5 Section 70.05-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation § 70.05-5 Penalty...
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Penalty. 70.05-5 Section 70.05-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation § 70.05-5 Penalty...
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Penalty. 70.05-5 Section 70.05-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation § 70.05-5 Penalty...
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Penalty. 70.05-5 Section 70.05-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION INTERFERENCE WITH OR DAMAGE TO AIDS TO NAVIGATION Collision With or Damage to Aids to Navigation § 70.05-5 Penalty...
Code of Federal Regulations, 2011 CFR
2011-10-01
... crashworthiness, and to realize any savings in collision insurance resulting from differences in damageability, and any savings in medical payment insurance resulting from differences in crashworthiness. ...
Code of Federal Regulations, 2014 CFR
2014-10-01
... crashworthiness, and to realize any savings in collision insurance resulting from differences in damageability, and any savings in medical payment insurance resulting from differences in crashworthiness. ...
Code of Federal Regulations, 2010 CFR
2010-10-01
... crashworthiness, and to realize any savings in collision insurance resulting from differences in damageability, and any savings in medical payment insurance resulting from differences in crashworthiness. ...
Code of Federal Regulations, 2013 CFR
2013-10-01
... crashworthiness, and to realize any savings in collision insurance resulting from differences in damageability, and any savings in medical payment insurance resulting from differences in crashworthiness. ...
Code of Federal Regulations, 2012 CFR
2012-10-01
... crashworthiness, and to realize any savings in collision insurance resulting from differences in damageability, and any savings in medical payment insurance resulting from differences in crashworthiness. ...
Nitric oxide-mediated oxidative damage and the progressive demise of motor neurons in ALS.
Drechsel, Derek A; Estévez, Alvaro G; Barbeito, Luis; Beckman, Joseph S
2012-11-01
Oxidative damage is a common and early feature of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS), and other neurodegenerative disorders. Dr. Mark Smith and his colleagues have built the case for oxidative stress being a primary progenitor rather than a secondary end-stage epiphenomenon of neurodegeneration. They proposed that reactive oxygen species contribute to the "age-related cascade of neurodegeneration," whereby accumulative oxidative damage with age promotes other characteristic pathological changes in afflicted brain regions, including protein aggregation, metabolic deficiencies, and inflammation. Nitric oxide (NO) likely plays a critical role in this age-related cascade. NO is a major signaling molecule produced in the central nervous system to modulate neurological activity through stimulating cyclic GMP synthesis. However, the same physiological concentrations of NO, relevant in cellular signaling, may also initiate and amplify oxidative damage by diffusion-limited reactions with superoxide (O(2)(•-)) to produce peroxynitrite (ONOO(-)). This is perhaps best illustrated in ALS where physiological levels of NO promote survival of motor neurons, but the same concentrations can stimulate motor neuron apoptosis and glial cell activation under pathological conditions. While these changes represent a complex mechanism involving multiple cell types in the pathogenesis of ALS, they also reveal general processes underlying neurodegeneration.
Dunn, Aaron; Dingreville, Remi; Capolungo, Laurent
2015-11-27
A hierarchical methodology is introduced to predict the effects of radiation damage and irradiation conditions on the yield stress and internal stress heterogeneity developments in polycrystalline α-Fe. Simulations of defect accumulation under displacement cascade damage conditions are performed using spatially resolved stochastic cluster dynamics. The resulting void and dislocation loop concentrations and average sizes are then input into a crystal plasticity formulation that accounts for the change in critical resolved shear stress due to the presence of radiation induced defects. The simulated polycrystalline tensile tests show a good match to experimental hardening data over a wide range of irradiation doses.more » With this capability, stress heterogeneity development and the effect of dose rate on hardening is investigated. The model predicts increased hardening at higher dose rates for low total doses. By contrast, at doses above 10 –2 dpa when cascade overlap becomes significant, the model does not predict significantly different hardening for different dose rates. In conclusion, the development of such a model enables simulation of radiation damage accumulation and associated hardening without relying on experimental data as an input under a wide range of irradiation conditions such as dose, dose rate, and temperature.« less
Moussawi, A; Derzsy, N; Lin, X; Szymanski, B K; Korniss, G
2017-09-15
Cascading failures are a critical vulnerability of complex information or infrastructure networks. Here we investigate the properties of load-based cascading failures in real and synthetic spatially-embedded network structures, and propose mitigation strategies to reduce the severity of damages caused by such failures. We introduce a stochastic method for optimal heterogeneous distribution of resources (node capacities) subject to a fixed total cost. Additionally, we design and compare the performance of networks with N-stable and (N-1)-stable network-capacity allocations by triggering cascades using various real-world node-attack and node-failure scenarios. We show that failure mitigation through increased node protection can be effectively achieved against single-node failures. However, mitigating against multiple node failures is much more difficult due to the combinatorial increase in possible sets of initially failing nodes. We analyze the robustness of the system with increasing protection, and find that a critical tolerance exists at which the system undergoes a phase transition, and above which the network almost completely survives an attack. Moreover, we show that cascade-size distributions measured in this region exhibit a power-law decay. Finally, we find a strong correlation between cascade sizes induced by individual nodes and sets of nodes. We also show that network topology alone is a weak predictor in determining the progression of cascading failures.
Temperature induced degradation mechanisms of AlInAs/InGaAs/InP quantum cascade lasers
NASA Astrophysics Data System (ADS)
Pierścińska, D.; Pierściński, K.; Płuska, M.; Sobczak, G.; Kuźmicz, A.; Gutowski, P.; Bugajski, M.
2018-01-01
In this paper, we report on the investigation of temperature induced degradation mode of quantum cascade lasers (QCLs) with an emphasis on the influence of different processing technology. We investigate and compare lattice matched AlInAs/InGaAs/InP QCLs of various constructions, i.e., double trench, buried heterostructure and ridge waveguide regarding thermal management, reliability and sources of degradation. The analysis was performed by CCD thermoreflectance spectroscopy, scanning electron microscope inspection and destructive analysis by focused ion beam etching, enabling determination of the source and mode of degradation for investigated lasers. Experimental temperature data relate temperature rise, arising from supply current, with device geometry. Results clearly indicate, that the buried heterostructure geometry, allows reaching the highest maximal operating current densities, before the degradation occurs. Microscopic images of degradation confirm that degradation includes the damage of the contact layer as well as damage of the active region layers.
"Isogaba Maware": quality control of genome DNA by checkpoints.
Kitazono, A; Matsumoto, T
1998-05-01
Checkpoints maintain the interdependency of cell cycle events by permitting the onset of an event only after the completion of the preceding event. The DNA replication checkpoint induces a cell cycle arrest until the completion of the DNA replication. Similarly, the DNA damage checkpoint arrests cell cycle progression if DNA repair is incomplete. A number of genes that play a role in the two checkpoints have been identified through genetic studies in yeasts, and their homologues have been found in fly, mouse, and human. They form signaling cascades activated by a DNA replication block or DNA damage and subsequently generate the negative constraints on cell cycle regulators. The failure of these signaling cascades results in producing offspring that carry mutations or that lack a portion of the genome. In humans, defects in the checkpoints are often associated with cancer-prone diseases. Focusing mainly on the studies in budding and fission yeasts, we summarize the recent progress.
Primary radiation damage of an FeCr alloy under pressure: Atomistic simulation
NASA Astrophysics Data System (ADS)
Tikhonchev, M. Yu.; Svetukhin, V. V.
2017-05-01
The primary radiation damage of a binary FeCr alloy deformed by applied mechanical loading is studied by an atomistic molecular dynamics simulation. Loading is simulated by specifying an applied pressure of 0.25, 1.0, and 2.5 GPa of both signs. Hydrostatic and uniaxial loading is considered along the [001], [111], [112], and [210] directions. The influence of loading on the energy of point defect formation and the threshold atomic displacement energy in single-component bcc iron is investigated. The 10-keV atomic displacement cascades in a "random" binary Fe-9 at % Cr alloy are simulated at an initial temperature of 300 K. The number of the point defects generated in a cascade is estimated, and the clustering of point defects and the spatial orientation of interstitial configurations are analyzed. Our results agree with the results of other researchers and supplement them.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mayer, J; Paul E. Johns, P
Wild pig (Sus scrofa) collisions with vehicles are known to occur in the United States, but only minimal information describing these accidents has been reported. In an effort to better characterize these accidents, data were collected from 179 wild pig-vehicle collisions from a location in west central South Carolina. Data included accident parameters pertaining to the animals involved, time, location, and human impacts. The age structure of the animals involved was significantly older than that found in the population. Most collisions involved single animals; however, up to seven animals were involved in individual accidents. As the number of animals permore » collision increased, the age and body mass of the individuals involved decreased. The percentage of males was significantly higher in the single-animal accidents. Annual attrition due to vehicle collisions averaged 0.8 percent of the population. Wild pig-vehicle collisions occurred year-round and throughout the 24-hour daily time period. Most accidents were at night. The presence of lateral barriers was significantly more frequent at the collision locations. Human injuries were infrequent but potentially serious. The mean vehicle damage estimate was $1,173.« less
Bears benefit plants via a cascade with both antagonistic and mutualistic interactions.
Grinath, Joshua B; Inouye, Brian D; Underwood, Nora
2015-02-01
Predators can influence primary producers by generating cascades of effects in ecological webs. These effects are often non-intuitive, going undetected because they involve many links and different types of species interactions. Particularly, little is understood about how antagonistic (negative) and mutualistic (positive) interactions combine to create cascades. Here, we show that black bears can benefit plants by consuming ants. The ants are mutualists of herbivores and protect herbivores from other arthropod predators. We found that plants near bear-damaged ant nests had greater reproduction than those near undamaged nests, due to weaker ant protection for herbivores, which allowed herbivore suppression by arthropod predators. Our results highlight the need to integrate mutualisms into trophic cascade theory, which is based primarily on antagonistic relationships. Predators are often conservation targets, and our results suggest that bears and other predators should be managed with the understanding that they can influence primary producers through many paths. © 2014 John Wiley & Sons Ltd/CNRS.
46 CFR 172.235 - Extent of damage.
Code of Federal Regulations, 2010 CFR
2010-10-01
... dimensions given in Table 172.235 except that, if the most disabling penetrations would be less than the... Damage Collision Penetration Longitudinal extent 0.495 L2/3 or 47.6 feet. (1/3 L2/3 or 14.5 m), whichever is less. Transverse extent 4 feet 2 inches (1.25 m).1 Vertical extent From the baseline upward...
46 CFR 172.235 - Extent of damage.
Code of Federal Regulations, 2011 CFR
2011-10-01
... dimensions given in Table 172.235 except that, if the most disabling penetrations would be less than the... Damage Collision Penetration Longitudinal extent 0.495 L2/3 or 47.6 feet. (1/3 L2/3 or 14.5 m), whichever is less. Transverse extent 4 feet 2 inches (1.25 m).1 Vertical extent From the baseline upward...
Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria
ERIC Educational Resources Information Center
Titze, Ingo R.; Hunter, Eric J.
2015-01-01
Purpose: School-teachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk. Method: Vibration dosimetry is reformulated with the inclusion of collision stress.…
Soft x-ray emission from solar wind charge exchange in the laboratory
NASA Astrophysics Data System (ADS)
Shimaya, H.; Ishida, T.; Ishikawa, S.; Suda, S.; Tanuma, H.; Akamatsu, H.; Ohashi, H.; Ijima, N.; Inoue, M.; Ezoe, Y.; Ishisaki, Y.; Ohashi, T.; Shinozaki, K.; Mitsuda, K.; Liu, L.; Wang, J.
2013-09-01
We have observed the emission spectra in collisions of bare oxygen ions with a helium gas target in the soft x-ray region with a window-less silicon drift detector at the collision energy range of 48-80 keV. The dominant soft x-ray emission corresponds to the 1s-2p transition of hydrogen-like oxygen O7+ produced by the single-electron charge exchange reaction. Other emission lines are the 1s-3p, 1s-4p and 1s-5p transitions of O7+, and also the 1s2-1s2p transition of O6+ produced by the true double-electron capture. The cascades from the upper states result in a large population of the 2p state, even though the direct capture into the 2p state is extremely scarcer than those into the 3p, 4p and 5p states.
Collisional Removal of O2 (c(sup 1) Sigma(sup-)(sub u), nu=9) by O2, N2, and He
NASA Technical Reports Server (NTRS)
Copeland, Richard A.; Knutsen, Karen; Onishi, Marc E.; Yalcin, Talat
1996-01-01
The collisional removal Of 02 molecules in selected vibrational levels of the c state is studied using a two-laser double-resonance technique. The output of the first laser excites the 02 to nu = 9 or 10 of the c Sigma - state, and the ultraviolet output of the second laser monitors specific rovibrational levels via resonance-enhanced ionization. The temporal evolution of the c Sigma u state vibrational level is observed by scanning the time delay between the two pulsed lasers. As the rate constants for 02 and N2 are similar in magnitude, N2 collisions dominate the removal rate in the earth's atmosphere. For v= 10 colliding with 02, we find a removal rate constant that is 2-5 times that for v=9 and that single quantum collision cascade is an important pathway for removal.
NASA Technical Reports Server (NTRS)
Dateo, Christopher; Huo, Winifred M.; Fletcher, Graham D.
2004-01-01
It has been suggested that the genotoxic effects of ionizing radiation in living cells are not caused by the highly energetic incident radiation, but rather are induced by less energetic secondary species generated, the most abundant of which are free electrons.' The secondary electrons will further react to cause DNA damage via indirect and direct mechanisms. Detailed knowledge of these mechanisms is ultimately important for the development of global models of cellular radiation damage. We are studying one possible mechanism for the formation cf DNA strand breaks involving dissociative ionization of the DNA sugar-phosphate backbone induced by secondary electron co!lisions. We will present ionization cross sections at electron collision energies between threshold and 10 KeV using the improved binary encounter dipole (iBED) formulation' Preliminary results of the possible dissociative ionization pathways will be presented. It is speculated that radical fragments produced from the dissociative ionization can further react, providing a possible mechanism for double strand breaks and base damage.
Corneal tissue ablation using 6.1 μm quantum cascade laser
NASA Astrophysics Data System (ADS)
Huang, Yong; Kang, Jin U.
2012-03-01
High absorption property of tissues in the IR range (λ> 2 μm) results in effective tissue ablation, especially near 3 μm. In the mid-infrared range, wavelengths of 6.1 μm and 6.45 μm fall into the absorption bands of the amide protein groups Amide-I and Amide-II, respectively. They also coincide with the deformation mode of water, which has an absorption peak at 6.1 μm. This coincidence makes 6.1 μm laser a better ablation tool that has promising effectiveness and minimum collateral damages than 3 μm lasers. In this work, we performed bovine corneal ablation test in-vitro using high-power 6.1μm quantum cascade laser (QCL) operated at pulse mode. Quantum cascade laser has the advantages of low cost, compact size and tunable wavelength, which makes it great alternative Mid-IR light source to conventional tunable free-electron lasers (FEL) for medical applications. Preliminary results show that effective corneal stroma craters were achieved with much less collateral damage in corneal tissue that contains less water. Future study will focus on optimizing the control parameters of QCL to attain neat and precise ablation of corneal tissue and development of high peak power QCL.
Wang, Tian; Chen, Jeannie
2014-10-17
Phototransduction is a G-protein signal transduction cascade that converts photon absorption to a change in current at the plasma membrane. Certain genetic mutations affecting the proteins in the phototransduction cascade cause blinding disorders in humans. Some of these mutations serve as a genetic source of "equivalent light" that activates the cascade, whereas other mutations lead to amplification of the light response. How constitutive phototransduction causes photoreceptor cell death is poorly understood. We showed that persistent G-protein signaling, which occurs in rod arrestin and rhodopsin kinase knock-out mice, caused a rapid and specific induction of the PERK pathway of the unfolded protein response. These changes were not observed in the cGMP-gated channel knock-out rods, an equivalent light condition that mimics light-stimulated channel closure. Thus transducin signaling, but not channel closure, triggers rapid cell death in light damage caused by constitutive phototransduction. Additionally, we show that in the albino light damage model cell death was not associated with increase in global protein ubiquitination or unfolded protein response induction. Taken together, these observations provide novel mechanistic insights into the cell death pathway caused by constitutive phototransduction and identify the unfolded protein response as a potential target for therapeutic intervention. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.
Dong, Liqun; Zhou, Shu; Yang, Xiaohua; Chen, Qianming; He, Yang; Huang, Wen
2013-07-01
Magnolol, an orally available compound from Magnolia officinalis used widely in traditional herbal medicine against a variety of neuronal diseases, possesses potent antioxidant properties and protects the brain against oxidative damage. The aim of the work is to examine the protective mechanisms of magnolol on human neuroblastoma SH-SY5Y cells against apoptosis induced by the neurotoxin acrolein, which can cause neurodegenerative disorders by inducing oxidative stress. By investigating the effect of magnolol on neural cell damage induced by the neurotoxin acrolein, we found that magnolol pretreatment significantly attenuated acrolein-induced oxidative stress through inhibiting reactive oxygen species accumulation caused by intracellular glutathione depletion and nicotinamide adenine dinucleotide phosphate oxidase activation. We next examined the signaling cascade(s) involved in magnolol-mediated antiapoptotic effects. The results showed that acrolein induced SH-SY5Y cell apoptosis by activating mitochondria/caspase and MEK/ERK signaling pathways. Our findings provide the first evidence that magnolol protects SH-SY5Y cells against acrolein-induced oxidative stress and prolongs SH-SY5Y cell survival through regulating JNK/mitochondria/caspase, PI3K/MEK/ERK, and PI3K/Akt/FoxO1 signaling pathways.
Collisional Cascades Following Triton's Capture
NASA Astrophysics Data System (ADS)
Cuk, Matija; Hamilton, Douglas P.; Stewart-Mukhopadhyay, Sarah T.
2017-10-01
Neptune's moon Triton is widely thought to have been captured from heliocentric orbit, most likely through binary dissociation (Agnor and Hamilton, 2006). Triton's original eccentric orbit must have been subsequently circularized by satellite tides (Goldreich et al. 1989). Cuk and Gladman (2005) found that Kozai oscillations make early tidal evolution inefficient, and have proposed that collisions between Triton and debris from pre-existing satellites was the dominant mechanism of shrinking Triton's large post-capture orbit. However, Cuk and Hamilton (DPS 2016), using numerical simulations and results of Stewart and Leinhardt (2012), have found that collisions between regular satellites are unlikely to be destructive, while collisions between prograde moons and Triton are certainly erosive if not catastrophic. An obvious outcome would be pre-existing moon material gradually grinding down Triton and making it reaccrete in the local Laplace plane, in conflict with Triton's large current inclination. We propose that the crucial ingredient for understanding the early evolution of the Neptunian system are the collisions between the moons and the prograde and retrograde debris originating from the pre-existing moons and Triton. In particular, we expect early erosive impact(s) on Triton to generate debris that will, in subsequent collisions, disrupt the regular satellites. If the retrograde material were to dominate at some planetocentric distances, the end result may be a large cloud or disk of retrograde debris that would be accreted by Triton, shrinking Triton's orbit. Some of the prograde debris could survive in a compact disk interior to Triton's pericenter, eventually forming the inner moons of Neptune. We will present results of numerical modeling of these complex dynamical processes at the meeting.
NASA Astrophysics Data System (ADS)
Nedeljković, N. N.; Majkić, M. D.; Božanić, D. K.; Dojčilović, R. J.
2016-06-01
We consider the population dynamics of the intermediate Rydberg states of highly charged ions (core charge Z\\gg 1, principal quantum number {n}{{A}}\\gg 1) interacting with solid surfaces at arbitrary collision geometry. The recently developed resonant two-state vector model for the grazing incidence (2012 J. Phys. B: At. Mol. Opt. Phys. 45 215202) is extended to the quasi-resonant case and arbitrary angle of incidence. According to the model, the population probabilities depend both on the projectile parallel and perpendicular velocity components, in a complementary way. A cascade neutralization process for {{{Xe}}}Z+ ions, for Z=15{--}45, interacting with a conductive-surface is considered by taking into account the population dynamics. For an arbitrary collision geometry and given range of ionic velocities, a micro-staircase model for the simultaneous calculation of the kinetic energy gain and the charge state of the ion in front of the surface is proposed. The relevance of the obtained results for the explanation of the formation of nanostructures on solid surfaces by slow highly charged ions for normal incidence geometry is briefly discussed.
46 CFR 172.180 - Extent of damage.
Code of Federal Regulations, 2011 CFR
2011-10-01
... penetrations having the dimensions given in Table 172.180 except that, if the most disabling penetrations would... 172.180—Extent of Damage Collision Penetration Longitudinal extent 0.495L2/3 or 47.6 feet ((1/3)L2/3 or 14.5m) whichever is shorter. Transverse extent 1 B/5 or 37.74 feet (11.5m) 2 whichever is shorter...
46 CFR 172.180 - Extent of damage.
Code of Federal Regulations, 2010 CFR
2010-10-01
... penetrations having the dimensions given in Table 172.180 except that, if the most disabling penetrations would... 172.180—Extent of Damage Collision Penetration Longitudinal extent 0.495L2/3 or 47.6 feet ((1/3)L2/3 or 14.5m) whichever is shorter. Transverse extent 1 B/5 or 37.74 feet (11.5m) 2 whichever is shorter...
46 CFR 172.135 - Extent of damage.
Code of Federal Regulations, 2010 CFR
2010-10-01
... penetrations having the dimensions given in Table 172.135 except that, if the most disabling penetrations would... 172.135—Extent of Damage Collision Penetration Longitudinal extent 0.495L 2/3 or 47.6 feet ((1/3)L 2/3 or 14.5m) whichever is shorter. Transverse extent 1 B/5 or 37.74 feet (11.5m) 2 whichever is shorter...
46 CFR 172.135 - Extent of damage.
Code of Federal Regulations, 2011 CFR
2011-10-01
... penetrations having the dimensions given in Table 172.135 except that, if the most disabling penetrations would... 172.135—Extent of Damage Collision Penetration Longitudinal extent 0.495L 2/3 or 47.6 feet ((1/3)L 2/3 or 14.5m) whichever is shorter. Transverse extent 1 B/5 or 37.74 feet (11.5m) 2 whichever is shorter...
Mitochondria, cognitive impairment, and Alzheimer's disease.
Mancuso, M; Calsolaro, V; Orsucci, D; Carlesi, C; Choub, A; Piazza, S; Siciliano, G
2009-07-06
To date, the beta amyloid (Abeta) cascade hypothesis remains the main pathogenetic model of Alzheimer's disease (AD), but its role in the majority of sporadic AD cases is unclear. The "mitochondrial cascade hypothesis" could explain many of the biochemical, genetic, and pathological features of sporadic AD. Somatic mutations in mitochondrial DNA (mtDNA) could cause energy failure, increased oxidative stress, and accumulation of Abeta, which in a vicious cycle reinforce the mtDNA damage and the oxidative stress. Despite the evidence of mitochondrial dysfunction in AD, no causative mutations in the mtDNA have been detected so far. Indeed, results of studies on the role of mtDNA haplogroups in AD are controversial. In this review we discuss the role of the mitochondria, and especially of the mtDNA, in the cascade of events leading to neurodegeneration, dementia, and AD.
Mitochondria, Cognitive Impairment, and Alzheimer's Disease
Mancuso, M.; Calsolaro, V.; Orsucci, D.; Carlesi, C.; Choub, A.; Piazza, S.; Siciliano, G.
2009-01-01
To date, the beta amyloid (Aβ) cascade hypothesis remains the main pathogenetic model of Alzheimer's disease (AD), but its role in the majority of sporadic AD cases is unclear. The “mitochondrial cascade hypothesis” could explain many of the biochemical, genetic, and pathological features of sporadic AD. Somatic mutations in mitochondrial DNA (mtDNA) could cause energy failure, increased oxidative stress, and accumulation of Aβ, which in a vicious cycle reinforce the mtDNA damage and the oxidative stress. Despite the evidence of mitochondrial dysfunction in AD, no causative mutations in the mtDNA have been detected so far. Indeed, results of studies on the role of mtDNA haplogroups in AD are controversial. In this review we discuss the role of the mitochondria, and especially of the mtDNA, in the cascade of events leading to neurodegeneration, dementia, and AD. PMID:20798880
Penetrative nature of high energy showers observed in Chacaltaya emulsion chamber
NASA Technical Reports Server (NTRS)
Funayama, Y.; Tamada, M.
1985-01-01
About 30% of single core showers with E (sup gamma) 10 TeV have stronger penetrating power than that expected from electromagnetic showers (e,gamma). On the other hand, their starting points of cascades in the chamber are found to be as shallow as those of (e,gamma) components. It is suggested that those showers are very collimated bundles of hadron and (e,gamma) component. Otherwise, it is assumed that the collision mean free path of those showers in the chamber is shorter than that of hadron with geometrical value.
Stimulated emission by hybrid transitions via a heteronuclear molecule
NASA Astrophysics Data System (ADS)
Dinev, S. G.; Khadzhikhristov, G. B.; Stefanov, I. L.
1990-03-01
An atomic emission, identified as a four-wave parametric emission and stimulated by collision assisted hybrid transition via a heteronuclear molecule, is presented together with a diagram of excitation and emission for the relevant K and NaK energy levels. The cascading emission from the excited 7S or 5D levels to lower-lying atomic states is considered to be insignificant. The dependence of the red signal and the NaK fluorescence on the pump energy is investigated, and the results can be used to indicate the onset of a stimulated process.
NASA Technical Reports Server (NTRS)
L'Hote, D.; Alard, J. P.; Augerat, J.; Babinet, R.; Brochard, F.; Fodor, Z.; Fraysse, L.; Girard, J.; Gorodetzky, P.; Gosset, J.;
1987-01-01
Mean multiplicities of pi+ and pi- in 4He collisions with C, Cu, and Pb at 200, 600, and 800 MeV/u, and with C and Pb at 400 MeV/u have been measured using the large solid angle detector Diogene. The independence of pion multiplicity on projectile incident energy, target mass and proton multiplicity is studied in comparison with intra-nuclear cascade predictions. The discrepancy between experimental results and theory is pointed out and discussed.
Collision management utilizing CCD and remote sensing technology
NASA Technical Reports Server (NTRS)
Mcdaniel, Harvey E., Jr.
1995-01-01
With the threat of damage to aerospace systems (space station, shuttle, hypersonic a/c, solar power satellites, loss of life, etc.) from collision with debris (manmade/artificial), there exists an opportunity for the design of a novel system (collision avoidance) to be incorporated into the overall design. While incorporating techniques from ccd and remote sensing technologies, an integrated system utilized in the infrared/visible spectrum for detection, tracking, localization, and maneuvering from doppler shift measurements is achievable. Other analysis such as impact assessment, station keeping, chemical, and optical tracking/fire control solutions are possible through this system. Utilizing modified field programmable gated arrays (software reconfiguring the hardware) the mission and mission effectiveness can be varied. This paper outlines the theoretical operation of a prototype system as it applies to collision avoidance (to be followed up by research).
Tang, Youming; Cao, Libo; Kan, Steven
2014-05-08
To examine the damage location distribution of five main body region injuries of maximum abbreviated injury score (MAIS) 3-6 injured occupants for nearside struck vehicle in front-to-side impact crashes. MAIS 3-6 injured occupants information was extracted from the US-National Automotive Sampling System/Crashworthiness Data System in the year 2007; it included the head/face/neck, chest, pelvis, upper extremity and lower extremity. Struck vehicle collision damage was classified in a three-dimensional system according to the J224 Collision Deformation Classification of SAE Surface Vehicle Standard. Nearside occupants seated directly adjacent to the struck side of the vehicle with MAIS 3-6 injured, in light truck vehicles-passenger cars (LTV-PC) side impact crashes. Distribution of MAIS 3-6 injured occupants by body regions and specific location of damage (lateral direction, horizontal direction and vertical direction) were examined. Injury risk ratio was also assessed. The lateral crush zone contributed to MAIS 3-6 injured occupants (n=705) and 50th centile injury risks when extended into zone 3. When the crush extended to zone 4, the injury risk ratio of MAIS 3-6 injured occupants approached 81%. The horizontal crush zones contributing to the highest injury risk ratio of MAIS 3-6 occupants were zones 'D' and 'Y', and the injury risk ratios were 25.4% and 36.9%, respectively. In contrast, the lowest injury risk ratio was 5.67% caused by zone 'B'. The vertical crush zone which contributed to the highest injury risk ratio of MAIS 3-6 occupants was zone 'E', whose injury risk ratio was 58%. In contrast, the lowest injury risk ratio was 0.14% caused by zone 'G+M'. The highest injury risk ratio of MAIS 3-6 injured occupants caused by crush intrusion between 40 and 60 cm in LTV-PC nearside impact collisions and the damage region of the struck vehicle was in the zones 'E' and 'Y'.
NASA Astrophysics Data System (ADS)
Schekochihin, A. A.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.
2009-05-01
This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulent motions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated by these scales, the fully kinetic problem is systematically reduced to a more physically transparent and computationally tractable system of equations, which are derived in a rigorous way. In the "inertial range" above the ion gyroscale, the kinetic cascade separates into two parts: a cascade of Alfvénic fluctuations and a passive cascade of density and magnetic-field-strength fluctuations. The former are governed by the reduced magnetohydrodynamic (RMHD) equations at both the collisional and collisionless scales; the latter obey a linear kinetic equation along the (moving) field lines associated with the Alfvénic component (in the collisional limit, these compressive fluctuations become the slow and entropy modes of the conventional MHD). In the "dissipation range" below ion gyroscale, there are again two cascades: the kinetic-Alfvén-wave (KAW) cascade governed by two fluid-like electron reduced magnetohydrodynamic (ERMHD) equations and a passive cascade of ion entropy fluctuations both in space and velocity. The latter cascade brings the energy of the inertial-range fluctuations that was Landau-damped at the ion gyroscale to collisional scales in the phase space and leads to ion heating. The KAW energy is similarly damped at the electron gyroscale and converted into electron heat. Kolmogorov-style scaling relations are derived for all of these cascades. The relationship between the theoretical models proposed in this paper and astrophysical applications and observations is discussed in detail.
The maintenance of genome integrity and function is essen-tial for the survival of cells and organisms. Any damage to our genetic material must be immediately sensed and repaired to preserve a cell’s func-tional integrity. Cells are constantly faced with the challenge of protecting their DNA from assaults by damaging chemicals and ultraviolet light. DNA damage that escapes repair can lead to a variety of genetic disorders and diseases, particularly cancer. To avoid this catastrophe, the cell employs an army of DNA repair factors that “rush to the scene” and initiate a cascade of events to repair the damage. Exactly how different repair factors sense DNA damage and orchestrate their concert-ed response is not well understood.
Dynamics of Helium-Loaded Grain Boundaries under Shear Deformation in α-Fe
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gao, Fei; Yang, Li; Heinisch, Howard L.
2014-03-30
The defects produced in collision cascades will interact with microstructural features in materials, such as GBs and dislocations. The coupled motion of GBs under stress has been widely observed in simulations and experiments. Two symmetric tilt GBs with a common <110> tilt axis (Σ3 and Σ11) in bcc iron are used to investigate the coupled motion of GBs under shear deformation. Also, we have explored the effect of self-interstitial atoms (SIAs) loading on the GB motion, with different concentrations of interstitials randomly inserted around the GB plane. The simulation results show that the interstitial loading reduces the critical stress ofmore » the GB coupled motion for the Σ3 GB. Furthermore, the interstitials and vacancies are inserted randomly at the GB plane and at a distance of 1 nm away from the GB plane, respectively, to understand the self-healing mechanism of GBs under stress. The behavior of the defect-loaded GBs depends on the GB structure. The loaded interstitials in the Σ3 GB easily form <111> interstitial clusters that do not move along with the GB. The vacancies in the Σ3 GB impede the GB motion. However, the interstitials move along with the Σ11 GB and annihilate with vacancies when the GB moves into the vacancy-rich region, leading to the self-healing and damage recovery of the Σ11 GB.« less
Why pleiotropic interventions are needed for Alzheimer's disease.
Frautschy, Sally A; Cole, Greg M
2010-06-01
Alzheimer's disease (AD) involves a complex pathological cascade thought to be initially triggered by the accumulation of beta-amyloid (Abeta) peptide aggregates or aberrant amyloid precursor protein (APP) processing. Much is known of the factors initiating the disease process decades prior to the onset of cognitive deficits, but an unclear understanding of events immediately preceding and precipitating cognitive decline is a major factor limiting the rapid development of adequate prevention and treatment strategies. Multiple pathways are known to contribute to cognitive deficits by disruption of neuronal signal transduction pathways involved in memory. These pathways are altered by aberrant signaling, inflammation, oxidative damage, tau pathology, neuron loss, and synapse loss. We need to develop stage-specific interventions that not only block causal events in pathogenesis (aberrant tau phosphorylation, Abeta production and accumulation, and oxidative damage), but also address damage from these pathways that will not be reversed by targeting prodromal pathways. This approach would not only focus on blocking early events in pathogenesis, but also adequately correct for loss of synapses, substrates for neuroprotective pathways (e.g., docosahexaenoic acid), defects in energy metabolism, and adverse consequences of inappropriate compensatory responses (aberrant sprouting). Monotherapy targeting early single steps in this complicated cascade may explain disappointments in trials with agents inhibiting production, clearance, or aggregation of the initiating Abeta peptide or its aggregates. Both plaque and tangle pathogenesis have already reached AD levels in the more vulnerable brain regions during the "prodromal" period prior to conversion to "mild cognitive impairment (MCI)." Furthermore, many of the pathological events are no longer proceeding in series, but are going on in parallel. By the MCI stage, we stand a greater chance of success by considering pleiotropic drugs or cocktails that can independently limit the parallel steps of the AD cascade at all stages, but that do not completely inhibit the constitutive normal functions of these pathways. Based on this hypothesis, efforts in our laboratories have focused on the pleiotropic activities of omega-3 fatty acids and the anti-inflammatory, antioxidant, and anti-amyloid activity of curcumin in multiple models that cover many steps of the AD pathogenic cascade (Cole and Frautschy, Alzheimers Dement 2:284-286, 2006).
A coupled effect of nuclear and electronic energy loss on ion irradiation damage in lithium niobate
Liu, Peng; Zhang, Yanwen; Xue, Haizhou; ...
2016-01-09
Understanding irradiation effects induced by elastic energy loss to atomic nuclei and inelastic energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO 3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low electronic energy loss is shown to induce observable damage that increases with ion fluence. For the same electronic energy loss,more » the velocity of the incident ion could affect the energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high electronic energy loss in pre-damaged LiNbO 3 has been observed. The result indicates that pre-existing damage induced from nuclear energy loss interacts synergistically with inelastic electronic energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by electronic energy loss. As a result, this synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense electronic energy deposition along high-energy ion trajectory.« less
Two-temperature model in molecular dynamics simulations of cascades in Ni-based alloys
Zarkadoula, Eva; Samolyuk, German; Weber, William J.
2017-01-03
In high-energy irradiation events, energy from the fast moving ion is transferred to the system via nuclear and electronic energy loss mechanisms. The nuclear energy loss results in the creation of point defects and clusters, while the energy transferred to the electrons results in the creation of high electronic temperatures, which can affect the damage evolution. In this paper, we perform molecular dynamics simulations of 30 keV and 50 keV Ni ion cascades in nickel-based alloys without and with the electronic effects taken into account. We compare the results of classical molecular dynamics (MD) simulations, where the electronic effects aremore » ignored, with results from simulations that include the electronic stopping only, as well as simulations where both the electronic stopping and the electron-phonon coupling are incorporated, as described by the two temperature model (2T-MD). Finally, our results indicate that the 2T-MD leads to a smaller amount of damage, more isolated defects and smaller defect clusters.« less
NASA Astrophysics Data System (ADS)
Ulmer, Christopher J.; Motta, Arthur T.
2017-11-01
The development of TEM-visible damage in materials under irradiation at cryogenic temperatures cannot be explained using classical rate theory modeling with thermally activated reactions since at low temperatures thermal reaction rates are too low. Although point defect mobility approaches zero at low temperature, the thermal spikes induced by displacement cascades enable some atom mobility as it cools. In this work a model is developed to calculate "athermal" reaction rates from the atomic mobility within the irradiation-induced thermal spikes, including both displacement cascades and electronic stopping. The athermal reaction rates are added to a simple rate theory cluster dynamics model to allow for the simulation of microstructure evolution during irradiation at cryogenic temperatures. The rate theory model is applied to in-situ irradiation of ZrC and compares well at cryogenic temperatures. The results show that the addition of the thermal spike model makes it possible to rationalize microstructure evolution in the low temperature regime.
Giampieri, Francesca; Alvarez-Suarez, Josè M; Cordero, Mario D; Gasparrini, Massimiliano; Forbes-Hernandez, Tamara Y; Afrin, Sadia; Santos-Buelga, Celestino; González-Paramás, Ana M; Astolfi, Paola; Rubini, Corrado; Zizzi, Antonio; Tulipani, Sara; Quiles, Josè L; Mezzetti, Bruno; Battino, Maurizio
2017-11-01
Dietary polyphenols have been recently proposed as activators of the AMP-activated protein kinase (AMPK) signaling pathway and this fact might explain the relationship between the consumption of polyphenol-rich foods and the slowdown of the progression of aging. In the present work, the effects of strawberry consumption were evaluated on biomarkers of oxidative damage and on aging-associated reductions in mitochondrial function and biogenesis for 8weeks in old rats. Strawberry supplementation increased antioxidant enzyme activities, mitochondrial biomass and functionality, and decreased intracellular ROS levels and biomarkers of protein, lipid and DNA damage (P<0.05). Furthermore, a significant (P<0.05) increase in the expression of the AMPK cascade genes, involved in mitochondrial biogenesis and antioxidant defences, was also detected after strawberry intake. These in vivo results were then verified in vitro on HepG2 cells, confirming the involvement of AMPK in the beneficial effects exerted by strawberry against aging progression. Copyright © 2017 Elsevier Ltd. All rights reserved.
Space-filling, multifractal, localized thermal spikes in Si, Ge and ZnO
NASA Astrophysics Data System (ADS)
Ahmad, Shoaib; Abbas, Muhammad Sabtain; Yousuf, Muhammad; Javeed, Sumera; Zeeshan, Sumaira; Yaqub, Kashif
2018-04-01
The mechanism responsible for the emission of clusters from heavy ion irradiated solids is proposed to be thermal spikes. Collision cascade-based theories describe atomic sputtering but cannot explain the consistently observed experimental evidence for significant cluster emission. Statistical thermodynamic arguments for thermal spikes are employed here for qualitative and quantitative estimation of the thermal spike-induced cluster emission from Si, Ge and ZnO. The evolving cascades and spikes in elemental and molecular semiconducting solids are shown to have fractal characteristics. Power law potential is used to calculate the fractal dimension. With the loss of recoiling particles' energy the successive branching ratios get smaller. The fractal dimension is shown to be dependent upon the exponent of the power law interatomic potential D = 1/2m. Each irradiating ion has the probability of initiating a space-filling, multifractal thermal spike that may sublime a localized region near the surface by emitting clusters in relative ratios that depend upon the energies of formation of respective surface vacancies.
Electron and Ion Reactions in Molecular Solids: from astrochemistry to radiobiology
NASA Astrophysics Data System (ADS)
Huels, Michael A.
2001-05-01
Wherever ionizing radiation interacts with matter, it initiates reaction cascades involving ions, radicals, and ballistic secondary electrons; these reactions occur on fs time-scales, and may lead to substantial physical and chemical modifications of a medium. Here I present measurements of 0-80 eV electron and ion reactions in condensed films ranging from simple to complex, and astrophysical to biological in nature. Targets contain either: small molecules, hydrocarbons of increasing complexity (incl. bases, sugars, single/double stranded DNA), molecules on rare gas matrices, or mixed cryogenic films resembling astrophysical or planetary surface ices containing O2, H2O, methane, and aromatic hydrocarbons. The basic electron or ion reaction mechanisms and pathways are found to be fundamentally universal, but are modulated by the physical and chemical nature of the medium; depending on the latter, a reaction cascade may lead to different end-points, e.g. a decrease in molecular complexity via molecular fragmentations, or increases in complexity via secondary ion collision induced synthesis of larger molecules in hydrocarbon rich surface ices.
NASA Astrophysics Data System (ADS)
Almeida, Diogo Alexandre Fialho de
Radiation-induced damage to biological systems, both direct and indirect processes, has increasingly come under scrutiny by the international scientific community due to recent findings that electrons are a very effective agent in damaging DNA/RNA. Indeed, much remains to be discovered regarding the exact physico-chemical processes that occur in the nascent stages of DNA/RNA damage by incident radiation. However, it is also known that electrons do not exist freely in the physiological medium, but rather solvated and/or pre-solvated states. This leads to the need for new techniques that can better explore the damaging role of "bound" electrons to DNA/RNA. The work presented in this thesis consists on the study of electron transfer in collisions of atomic species with molecules of biological relevance. In order to study these processes, two experimental setups were used. One setup consists of a crossed beam experiment where a neutral potassium beam is created and made to collide with an effusive molecular target beam. The anionic products that stem from electron transfer in potassium atom to the molecular target collisions are then extracted and time-of-flight (TOF) mass analysed. In the second setup a beam of anionic species is formed and made to collide with a molecular target. Collisions with three different anionic beams were performed (H-, O- and OH-), as well as with different simple organic molecules, by measuring the positive and negative ion fragmentation patterns with a quadrupole mass spectrometer (QMS). A comparison between these two collisional systems can greatly help to understand the underlying mechanisms of the electron transfer processes. Finally, studies of potassium collisions with sugar surrogates D-Ribose and THF were performed. These studies show very different fragmentation patterns from DEA, although in the case of THF, it is suggested that the initially accessed states are the same as in DEA. With these studies was also possible to show for the first time collision induced site and bond selectivity breaking, where the electron is transferred into a given state of the acceptor molecule and the resulting fragmentation pathways are exclusive to the initial anionic state. Furthermore, the role of the potassium cation post collisionwas explored and indeed its presence is suggested to induce at least partial suppression of auto-detachment. The implications that ensue from this degradation are analysed in the light of the obtained fragmentation patterns.
Smiley, A M
1990-10-01
In February of 1986 a head-on collision occurred between a freight train and a passenger train in western Canada killing 23 people and causing over $30 million of damage. A Commission of Inquiry appointed by the Canadian government concluded that human error was the major reason for the collision. This report discusses the factors contributing to the human error: mainly poor work-rest schedules, the monotonous nature of the train driving task, insufficient information about train movements, and the inadequate backup systems in case of human error.
2012-08-01
between fat score (Helms and Drury 1960) and the condition index (R2 = 0.56, P < 0.001). A condition index of zero corresponds to zero fat stores or...where bird-wildlife/aircraft collisions threaten lives and cost millions of dollars in damages to aircraft infrastructure every year. By identifying...from bird-aircraft strikes (Dolbeer 2006). In the United States, collisions between aircraft and wildlife cost the aviation industry over $600
Bortsov, A V; Platts-Mills, T F; Peak, D A; Jones, J S; Swor, R A; Domeier, R M; Lee, D C; Rathlev, N K; Hendry, P L; Fillingim, R B; McLean, S A
2013-09-01
Musculoskeletal pain is common after motor vehicle collision (MVC). The study objective was to evaluate distribution of pain and predictors of widespread musculoskeletal pain in the early aftermath (within 48 h) of collision. European American adults aged 18-65 years presenting to the emergency department (ED) after collision who were discharged to home after evaluation were eligible. Evaluation included an assessment of reported pre-collision psychological characteristics, crash characteristics, current pain severity and location, and current psychological symptoms. Adjusted risk ratios were estimated using generalized linear models. Among 890 participants included in the study, 589/890 (66%) had pain in three or more regions, and 192/890 (22%) had widespread musculoskeletal pain (pain in seven or more regions). In adjusted analyses, the presence of widespread pain was strongly associated with depressive and somatic symptoms prior to collision, pain catastrophizing, and acute psychological symptoms, and was not associated with most collision characteristics (road speed limit, extent of vehicle damage, collision type, driver vs. passenger, airbag deployment). The reported number of body regions that struck an object during the collision was associated with both reported pre-collision depressive symptoms and with widespread pain. More than one in five individuals presenting to the ED in the hours after MVC have widespread pain. Widespread pain is strongly associated with patient characteristics known to be modulated by supraspinal mechanisms, suggesting that stress-induced hyperalgesia may influence acute widespread pain after collision. © 2013 European Federation of International Association for the Study of Pain Chapters.
Rodrigues, Roberto; Petersen, Robert B; Perry, George
2014-10-01
The thesis of this review is that oxidative stress is the central factor in major depressive disorder (MDD) and Alzheimer's disease (AD). The major elements involved are inflammatory cytokines, the hypothalamic-pituitary axis, the hypothalamic-pituitary gonadal, and arginine vasopressin systems, which induce glucocorticoid and "oxidopamatergic" cascades when triggered by psychosocial stress, severe life-threatening events, and mental-affective and somatic diseases. In individuals with a genomic vulnerability to depression, these cascades may result in chronic depression-anxiety-stress spectra, resulting in MDD and other known depressive syndromes. In contrast, in subjects with genomic vulnerability to AD, oxidative stress-induced brain damage triggers specific antioxidant defenses, i.e., increased levels of amyloid-β (Aβ) and aggregation of hyper-phosphorylated tau, resulting in paired helical filaments and impaired functions related to the ApoEε4 isoform, leading to complex pathological cascades culminating in AD. Surprisingly, all the AD-associated molecular pathways mentioned in this review have been shown to be similar or analogous to those found in depression, including structural damage, i.e., hippocampal and frontal cortex atrophy. Other interacting molecular signals, i.e., GSK-3β, convergent survival factors (brain-derived neurotrophic factor and heat shock proteins), and transition redox metals are also mentioned to emphasize the vast array of intermediates that could interact via comparable mechanisms in both MDD and AD.
Rodrigues, Roberto; Petersen, Robert B.
2014-01-01
The thesis of this review is that oxidative stress is the central factor in major depressive disorder (MDD) and Alzheimer’s disease (AD). The major elements involved are inflammatory cytokines, the hypothalamic pituitary axis, the hypothalamic pituitary gonadal, and arginine vasopressin systems, which induce glucocorticoid and “oxidopamatergic” cascades when triggered by psychosocial stress, severe life threatening events, and mental-affective and somatic diseases. In individuals with a genomic vulnerability to depression these cascades may result in chronic depression-anxiety-stress spectra, resulting in MDD and other known depressive syndromes. In contrast, in subjects with genomic vulnerability to Alzheimer’s disease, oxidative stress-induced brain damage triggers specific antioxidant defenses, i.e. increased levels of amyloid-β (Aβ) and aggregation of hyper-phosphorylated tau, resulting in paired helical filaments and impaired functions related to the ApoEε4 isoform, leading to complex pathological cascades culminating in AD. Surprisingly, all the AD associated molecular pathways mentioned in this review have been shown to be similar or analogous to those found in depression, including structural damage, i.e. hippocampal and frontal cortex atrophy. Other interacting molecular signals, i.e. GSK-3β, convergent survival factors (brain-derived neurotrophic factor and heat shock proteins), and transition-redox metals are also mentioned to emphasize the vast array of intermediates that could interact via comparable mechanisms in both MDD and AD. PMID:24927694
Heavy Quark Correlations and J / Φ Production in Heavy Ion Collisions
NASA Astrophysics Data System (ADS)
Niazi, Reza; Liu, Yunpeng; Ko, Che-Ming
2014-09-01
Quark Gluon Plasma (QGP), a phase of QCD matter, was the temporary state that all matter had in the universe microseconds after its creation, which has been produced in high energy nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Normally being bound inside a proton or neutron, due to the strong nuclear force, the QGP is a hot ``soup'' of quarks and gluons that move relatively freely. QGP is still a very enigmatic state of matter; therefore, active work is being done in trying to understand what is left behind after this short-lived state of matter disintegrates. This includes the abundance of the charmonium meson that consists of a pair of heavy charm and anticharm quarks. In this study, a QGP simulation called the Parton Cascade Model is used with two different initial conditions to see if charm and anticharm quarks can create a charmonium meson in the expanding QGP. In the simulation, the charm quark pair is initially either correlated, with opposite momenta but same position, or uncorrelated, with random momenta and positions, within the QGP. Understanding the difference of the amount of charmonium mesons produced in these two conditions will be helpful in developing theoretical models for charmonium production in heavy ion collisions and thus determining the properties of QGP from experimental measurements. Quark Gluon Plasma (QGP), a phase of QCD matter, was the temporary state that all matter had in the universe microseconds after its creation, which has been produced in high energy nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Normally being bound inside a proton or neutron, due to the strong nuclear force, the QGP is a hot ``soup'' of quarks and gluons that move relatively freely. QGP is still a very enigmatic state of matter; therefore, active work is being done in trying to understand what is left behind after this short-lived state of matter disintegrates. This includes the abundance of the charmonium meson that consists of a pair of heavy charm and anticharm quarks. In this study, a QGP simulation called the Parton Cascade Model is used with two different initial conditions to see if charm and anticharm quarks can create a charmonium meson in the expanding QGP. In the simulation, the charm quark pair is initially either correlated, with opposite momenta but same position, or uncorrelated, with random momenta and positions, within the QGP. Understanding the difference of the amount of charmonium mesons produced in these two conditions will be helpful in developing theoretical models for charmonium production in heavy ion collisions and thus determining the properties of QGP from experimental measurements. Funded by DOE and NSF-REU Program.
On the failure behaviour to striking bow penetration of impacted marine-steel structures
NASA Astrophysics Data System (ADS)
Prabowo, Aditya Rio; Muttaqie, Teguh; Sohn, Jung Min; Bae, Dong Myung; Setiyawan, Agus
2018-04-01
Demands for water transportation modes are continuously increasing as rapid economic and industrial growths in the recent decade. Ship as representative of the water transportation is generally needed to carry various products from one location to another. Besides as product carrier, ship also acts as public facility to transport human across islands for number of reasons, such as tourism and vehicle. Considering its importance, structural damage due to accidental loads or so-called impact can cause unacceptable casualties which threat ship passenger, shipping industry and maritime environment in same time. The most frequent impact phenomena occur in forms of collision and grounding, which are targeting side structure and double bottom consecutively. However, since responses of the impacts on structure are highly nonlinear and vary due to development of ship structures, sustainable analysis as an update of pioneer calculation can be beneficial as rational reference for improving safety and navigational instruments. This work aims to assess failures of the side structures subjected to penetration of striking bow in ship-ship collision scenario. Locations of impact are idealized to happen on after-end, midsection and fore-end to provide complete assessment. Striking bow is to be deployed by varying input velocity to observe significance of the fractures on the side structure. This configuration is implemented on the designed collision scenario, and later calculated using nonlinear finite element method (NLFEM). Summary of the solution indicated that the midsection produced the highest resistance against side collision. Breaching of the inner shell was successfully avoided on the fore-end, but the critical damage to the cargo was observed during bow penetration to the after-end region. This location was recommended to be added by longitudinal framing to increase its resistance against ship collision.
The replisome uses mRNA as a primer after colliding with RNA polymerase.
Pomerantz, Richard T; O'Donnell, Mike
2008-12-11
Replication forks are impeded by DNA damage and protein-nucleic acid complexes such as transcribing RNA polymerase. For example, head-on collision of the replisome with RNA polymerase results in replication fork arrest. However, co-directional collision of the replisome with RNA polymerase has little or no effect on fork progression. Here we examine co-directional collisions between a replisome and RNA polymerase in vitro. We show that the Escherichia coli replisome uses the RNA transcript as a primer to continue leading-strand synthesis after the collision with RNA polymerase that is displaced from the DNA. This action results in a discontinuity in the leading strand, yet the replisome remains intact and bound to DNA during the entire process. These findings underscore the notable plasticity by which the replisome operates to circumvent obstacles in its path and may explain why the leading strand is synthesized discontinuously in vivo.
49 CFR 178.338-10 - Accident damage protection.
Code of Federal Regulations, 2011 CFR
2011-10-01
..., enclosure, or protective device or structure (exclusive of wheel assemblies), must be at least 14 inches... transmit the force of the collision directly to the chassis of the vehicle. The rear-end tank protection...
49 CFR 178.338-10 - Accident damage protection.
Code of Federal Regulations, 2012 CFR
2012-10-01
..., enclosure, or protective device or structure (exclusive of wheel assemblies), must be at least 14 inches... transmit the force of the collision directly to the chassis of the vehicle. The rear-end tank protection...
49 CFR 178.338-10 - Accident damage protection.
Code of Federal Regulations, 2013 CFR
2013-10-01
..., enclosure, or protective device or structure (exclusive of wheel assemblies), must be at least 14 inches... transmit the force of the collision directly to the chassis of the vehicle. The rear-end tank protection...
49 CFR 178.338-10 - Accident damage protection.
Code of Federal Regulations, 2014 CFR
2014-10-01
..., enclosure, or protective device or structure (exclusive of wheel assemblies), must be at least 14 inches... transmit the force of the collision directly to the chassis of the vehicle. The rear-end tank protection...
49 CFR 178.338-10 - Accident damage protection.
Code of Federal Regulations, 2010 CFR
2010-10-01
..., enclosure, or protective device or structure (exclusive of wheel assemblies), must be at least 14 inches... must transmit the force of the collision directly to the chassis of the vehicle. The rear-end tank...
Evaluation of residual strength in the basalt fiber reinforced composites under impact damage
NASA Astrophysics Data System (ADS)
Kim, Yun-Hae; Lee, Jin-Woo; Moon, Kyung-Man; Yoon, Sung-Won; Baek, Tae-Sil; Hwang, Kwang-Il
2015-03-01
Composites are vulnerable to the impact damage by the collision as to the thickness direction, because composites are being manufactured by laminating the fiber. The understanding about the retained strength after the impact damage of the material is essential in order to secure the reliability of the structure design using the composites. In this paper, we have tried to evaluate the motion of the material according to the kinetic energy and potential energy and the retained strength after impact damage by testing the free fall test of the basalt fiber reinforced composite in the limelight as the environment friendly characteristic.
The use of the SRIM code for calculation of radiation damage induced by neutrons
NASA Astrophysics Data System (ADS)
Mohammadi, A.; Hamidi, S.; Asadabad, Mohsen Asadi
2017-12-01
Materials subjected to neutron irradiation will being evolve to structural changes by the displacement cascades initiated by nuclear reaction. This study discusses a methodology to compute primary knock-on atoms or PKAs information that lead to radiation damage. A program AMTRACK has been developed for assessing of the PKAs information. This software determines the specifications of recoil atoms (using PTRAC card of MCNPX code) and also the kinematics of interactions. The deterministic method was used for verification of the results of (MCNPX+AMTRACK). The SRIM (formely TRIM) code is capable to compute neutron radiation damage. The PKAs information was extracted by AMTRACK program, which can be used as an input of SRIM codes for systematic analysis of primary radiation damage. Then the Bushehr Nuclear Power Plant (BNPP) radiation damage on reactor pressure vessel is calculated.
Lv, Yanni; Qian, Yisong; Ou-Yang, Aijun; Fu, Longsheng
2016-11-01
Microglia activation initiates a neurological deficit cascade that contributes to substantial neuronal damage and impairment following ischemia stroke. Toll-like receptor 4 (TLR4) has been demonstrated to play a critical role in this cascade. In the current study, we tested the hypothesis that hydroxysafflor yellow A (HSYA), an active ingredient extracted from Flos Carthami tinctorii, alleviated inflammatory damage, and mediated neurotrophic effects in neurons by inducing the TLR4 pathway in microglia. A non-contact Transwell co-culture system comprised microglia and neurons was treated with HSYA followed by a 1 mg/mL lipopolysaccharide (LPS) stimulation. The microglia were activated prior to neuronal apoptosis, which were induced by increasing TLR4 expression in the activated microglia. However, HSYA suppressed TLR4 expression in the activated microglia, resulting in less neuronal damage at the early stage of LPS stimulation. Western blot analysis and immunofluorescence indicated that dose-dependently HSYA down-regulated TLR4-induced downstream effectors myeloid differentiation factor 88 (MyD88), nuclear factor kappa b (NF-κB), and the mitogen-activated protein kinases (MAPK)-regulated proteins c-Jun NH2-terminal protein kinase (JNK), protein kinase (ERK) 1/2 (ERK1/2), p38 MAPK (p38), as well as the LPS-induced inflammatory cytokine release. However, HSYA up-regulated brain-derived neurotrophic factor (BDNF) expression. Our data suggest that HSYA could exert neurotrophic and anti-inflammatory functions in response to LPS stimulation by inhibiting TLR4 pathway-mediated signaling.
NASA Astrophysics Data System (ADS)
Samolyuk, G. D.; Osetsky, Y. N.; Stoller, R. E.
2015-10-01
We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascade production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (∼0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential. The Gao-Weber potential appears to give a more realistic description of cascade dynamics in SiC, but still has some shortcomings when the defect migration barriers are compared to the ab initio results.
Isaksson-Hellman, Irene; Lindman, Magdalena
2016-09-01
The aim of the present study was to evaluate the crash mitigation performance of low-speed automated emergency braking collision avoidance technologies by examining crash rates, car damage, and personal injuries. Insurance claims data were used to identify rear-end frontal collisions, the specific situations where the low-speed automated emergency braking system intervenes. We compared cars of the same model (Volvo V70) with and without the low-speed automated emergency braking system (AEB and no AEB, respectively). Distributions of spare parts required for car repair were analyzed to identify car damage, and crash severity was estimated by comparing the results with laboratory crash tests. Repair costs and occupant injuries were investigated for both the striking and the struck vehicle. Rear-end frontal collisions were reduced by 27% for cars with low-speed AEB compared to cars without the system. Those of low severity were reduced by 37%, though more severe crashes were not reduced. Accordingly, the number of injured occupants in vehicles struck by low-speed AEB cars was reduced in low-severity crashes. In offset crash configurations, the system was found to be less effective. This study adds important information about the safety performance of collision avoidance technologies, beyond the number of crashes avoided. By combining insurance claims data and information from spare parts used, the study demonstrates a mitigating effect of low-speed AEB in real-world traffic.
Study on Collision of Ship Side Structure by Simplified Plastic Analysis Method
NASA Astrophysics Data System (ADS)
Sun, C. J.; Zhou, J. H.; Wu, W.
2017-10-01
During its lifetime, a ship may encounter collision or grounding and sustain permanent damage after these types of accidents. Crashworthiness has been based on two kinds of main methods: simplified plastic analysis and numerical simulation. A simplified plastic analysis method is presented in this paper. Numerical methods using the non-linear finite-element software LS-DYNA are conducted to validate the method. The results show that, as for the accuracy of calculation results, the simplified plasticity analysis are in good agreement with the finite element simulation, which reveals that the simplified plasticity analysis method can quickly and accurately estimate the crashworthiness of the side structure during the collision process and can be used as a reliable risk assessment method.
Hydrodynamic effects on cells in agitated tissue culture reactors
NASA Technical Reports Server (NTRS)
Cherry, R. S.; Papoutsakis, E. T.
1986-01-01
The mechanisms by which hydrodynamic forces can affect cells grown on microcarrier beads in agitated cell culture reactors were investigated by analyzing the motion of microcarriers relative to the surrounding fluid, to each other, and to moving or stationary solid surfaces. It was found that harmful effects on cell cultures that have been previously attributed to shear can be better explained as the effects of turbulence (of a size scale comparable to the microcarriers or the spacing between them) or collisions. The primary mechanisms of cell damage involve direct interaction between microcarriers and turbulent eddies, collisions between microcarriers in turbulent flow, and collisions against the impeller or other solid surfaces. The implications of these analytical results for the design of tissue culture reactors are discussed.
Jerome S. Beatty; Gregory M. Filip; Robert L. Mathiason
1997-01-01
Larch dwarf mistletoe (Arceuthobium laricis (Piper) St. John) is a common and damaging parasite of western larch (Larix occidentalis Nutt.) in the Pacific Northwest and southern British Columbia. Larch dwarf mistletoe occurs commonly throughout the range of western larch in British Columbia, northern and central Idaho, western Montana and east of the Cascades in...
Importance of initial and final state effects for azimuthal correlations in p + Pb collisions
Greif, Moritz; Greiner, Carsten; Schenke, Bjorn; ...
2017-11-27
In this work, we investigate the relative importance of initial and final state effects on azimuthal correlations of gluons in low and high multiplicity p+Pb collisions. To achieve this, we couple Yang-Mills dynamics of pre-equilibrium gluon fields (IP-GLASMA) to a perturbative QCD based parton cascade for the final state evolution (BAMPS) on an event-by-event basis. We find that signatures of both the initial state correlations and final state interactions are seen in azimuthal correlation observables, such as v 2 {2PC} (p T), their strength depending on the event multiplicity and transverse momentum. Initial state correlations dominate v 2 {2PC} (pmore » T) in low multiplicity events for transverse momenta p T > 2 GeV. Lastly, while final state interactions are dominant in high multiplicity events, initial state correlations affect v 2 {2PC} (p T) for p T > 2 GeV as well as the pT integrated v 2 {2PC}.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
El-Atwani, O.; Norris, S. A.; Ludwig, K.
In this study, several proposed mechanisms and theoretical models exist concerning nanostructure evolution on III-V semiconductors (particularly GaSb) via ion beam irradiation. However, making quantitative contact between experiment on the one hand and model-parameter dependent predictions from different theories on the other is usually difficult. In this study, we take a different approach and provide an experimental investigation with a range of targets (GaSb, GaAs, GaP) and ion species (Ne, Ar, Kr, Xe) to determine new parametric trends regarding nanostructure evolution. Concurrently, atomistic simulations using binary collision approximation over the same ion/target combinations were performed to determine parametric trends onmore » several quantities related to existing model. A comparison of experimental and numerical trends reveals that the two are broadly consistent under the assumption that instabilities are driven by chemical instability based on phase separation. Furthermore, the atomistic simulations and a survey of material thermodynamic properties suggest that a plausible microscopic mechanism for this process is an ion-enhanced mobility associated with energy deposition by collision cascades.« less
NASA Astrophysics Data System (ADS)
Wielanek, D.
2017-08-01
Femtoscopy is a tool to study the space-time evolution of hot and dense matter during high energy collision by using two-particle correlations. The femtoscopic and flow measurements at RHIC and LHC energies are well reproduced by the hydrodynamics models that contains equation of state (EoS) with crossover type transition from Quark-Gluon Plasma to hadron gas phase. Similar studies where performed at AGS and SPS accelerators and was performed in Beam Energy Scan (BES) program at Relativistic Heavy Ion Collider for exploring phase diagram of QCD matter. I present the femtoscopic observables calculated for Au-Au collisions at √sNN = 7:7 - 62:4 GeV calculated from viscous hydro + cascade model vHLLE+UrQMD with two types of EoSs - one that correspond to 1st order phase transition (PT) and second that correspond to crossover PT. I also discuss perspectives of femtoscopic measurements at NICA energy scale √sNN = 4 - 11 GeV.1
Importance of initial and final state effects for azimuthal correlations in p + Pb collisions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Greif, Moritz; Greiner, Carsten; Schenke, Bjorn
In this work, we investigate the relative importance of initial and final state effects on azimuthal correlations of gluons in low and high multiplicity p+Pb collisions. To achieve this, we couple Yang-Mills dynamics of pre-equilibrium gluon fields (IP-GLASMA) to a perturbative QCD based parton cascade for the final state evolution (BAMPS) on an event-by-event basis. We find that signatures of both the initial state correlations and final state interactions are seen in azimuthal correlation observables, such as v 2 {2PC} (p T), their strength depending on the event multiplicity and transverse momentum. Initial state correlations dominate v 2 {2PC} (pmore » T) in low multiplicity events for transverse momenta p T > 2 GeV. Lastly, while final state interactions are dominant in high multiplicity events, initial state correlations affect v 2 {2PC} (p T) for p T > 2 GeV as well as the pT integrated v 2 {2PC}.« less
Aad, G.; Abbott, B.; Abdallah, J.; ...
2011-07-09
Results are presented of a search for supersymmetric particles decaying into final states with significant missing transverse momentum and exactly two identical flavour leptons (e, μ) of opposite charge in √s = 7 TeV collisions at the Large Hadron Collider. This channel is particularly sensitive to supersymmetric particle cascade decays producing flavour correlated lepton pairs. Flavour uncorrelated backgrounds are subtracted using a sample of opposite flavour lepton pair events. Observation of an excess beyond Standard Model expectations following this subtraction procedure would offer one of the best routes to measuring the masses of supersymmetric particles. In a data sample correspondingmore » to an integrated luminosity of 35 pb⁻¹ no such excess is observed. Model-independent limits are set on the contribution to these final states from new physics and are used to exclude regions of a phenomenological supersymmetric parameter space.« less
NASA Astrophysics Data System (ADS)
Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Alam, M. S.; Alam, M. A.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Andeen, T.; Anders, C. F.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonelli, S.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Aubert, B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Dos Santos Pedrosa, F. Baltasar; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, D.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Battistoni, G.; Bauer, F.; Bawa, H. S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Harpaz, S. Behar; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ami, S. Ben; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bona, M.; Bondarenko, V. G.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Booth, P.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Brett, N. D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brubaker, E.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.; Buchanan, J.; Buchanan, N. J.; Buchholz, P.; Buckingham, R. M.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Budick, B.; Büscher, V.; Bugge, L.; Buira-Clark, D.; Buis, E. J.; Bulekov, O.; Bunse, M.; Buran, T.; Burckhart, H.; Burdin, S.; Burgess, T.; Burke, S.; Busato, E.; Bussey, P.; Buszello, C. P.; Butin, F.; Butler, B.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Buttinger, W.; Byatt, T.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Caloi, R.; Calvet, D.; Calvet, S.; Camacho Toro, R.; Camard, A.; Camarri, P.; Cambiaghi, M.; Cameron, D.; Cammin, J.; Campana, S.; Campanelli, M.; Canale, V.; Canelli, F.; Canepa, A.; Cantero, J.; Capasso, L.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capriotti, D.; Capua, M.; Caputo, R.; Caramarcu, C.; Cardarelli, R.; Carli, T.; Carlino, G.; Carminati, L.; Caron, B.; Caron, S.; Carpentieri, C.; Carrillo Montoya, G. D.; Carter, A. A.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Cascella, M.; Caso, C.; Castaneda Hernandez, A. M.; Castaneda-Miranda, E.; Castillo Gimenez, V.; Castro, N. F.; Cataldi, G.; Cataneo, F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Cattani, G.; Caughron, S.; Cauz, D.; Cavallari, A.; Cavalleri, P.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Cazzato, A.; Ceradini, F.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cetin, S. A.; Cevenini, F.; Chafaq, A.; Chakraborty, D.; Chan, K.; Chapleau, B.; Chapman, J. D.; Chapman, J. W.; Chareyre, E.; Charlton, D. G.; Chavda, V.; Cheatham, S.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, L.; Chen, S.; Chen, T.; Chen, X.; Cheng, S.; Cheplakov, A.; Chepurnov, V. F.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Cheung, S. L.; Chevalier, L.; Chiefari, G.; Chikovani, L.; Childers, J. T.; Chilingarov, A.; Chiodini, G.; Chizhov, M. V.; Choudalakis, G.; Chouridou, S.; Christidi, I. A.; Christov, A.; Chromek-Burckhart, D.; Chu, M. L.; Chudoba, J.; Ciapetti, G.; Ciba, K.; Ciftci, A. K.; Ciftci, R.; Cinca, D.; Cindro, V.; Ciobotaru, M. D.; Ciocca, C.; Ciocio, A.; Cirilli, M.; Ciubancan, M.; Clark, A.; Clark, P. J.; Cleland, W.; Clemens, J. C.; Clement, B.; Clement, C.; Clifft, R. W.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Coe, P.; Cogan, J. G.; Coggeshall, J.; Cogneras, E.; Cojocaru, C. D.; Colas, J.; Colijn, A. P.; Collard, C.; Collins, N. J.; Collins-Tooth, C.; Collot, J.; Colon, G.; Comune, G.; Conde Muiño, P.; Coniavitis, E.; Conidi, M. C.; Consonni, M.; Constantinescu, S.; Conta, C.; Conventi, F.; Cook, J.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cooper-Smith, N. J.; Copic, K.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Costin, T.; Côté, D.; Coura Torres, R.; Courneyea, L.; Cowan, G.; Cowden, C.; Cox, B. E.; Cranmer, K.; Crescioli, F.; Cristinziani, M.; Crosetti, G.; Crupi, R.; Crépé-Renaudin, S.; Almenar, C. Cuenca; Cuhadar Donszelmann, T.; Cuneo, S.; Curatolo, M.; Curtis, C. J.; Cwetanski, P.; Czirr, H.; Czyczula, Z.; D'Auria, S.; D'Onofrio, M.; D'Orazio, A.; Da Rocha Gesualdi Mello, A.; Da Silva, P. V. M.; Da Via, C.; Dabrowski, W.; Dahlhoff, A.; Dai, T.; Dallapiccola, C.; Dallison, S. J.; Dam, M.; Dameri, M.; Damiani, D. S.; Danielsson, H. O.; Dankers, R.; Dannheim, D.; Dao, V.; Darbo, G.; Darlea, G. L.; Daum, C.; Dauvergne, J. P.; Davey, W.; Davidek, T.; Davidson, N.; Davidson, R.; Davies, M.; Davison, A. R.; Dawe, E.; Dawson, I.; Dawson, J. W.; Daya, R. K.; De, K.; de Asmundis, R.; De Castro, S.; De Castro Faria Salgado, P. E.; De Cecco, S.; de Graat, J.; De Groot, N.; de Jong, P.; De La Taille, C.; De la Torre, H.; De Lotto, B.; De Mora, L.; De Nooij, L.; De Oliveira Branco, M.; De Pedis, D.; de Saintignon, P.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vivie De Regie, J. B.; Dean, S.; Dedovich, D. V.; Degenhardt, J.; Dehchar, M.; Deile, M.; Del Papa, C.; Del Peso, J.; Del Prete, T.; Dell'Acqua, A.; Dell'Asta, L.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delpierre, P.; Delruelle, N.; Delsart, P. A.; Deluca, C.; Demers, S.; Demichev, M.; Demirkoz, B.; Deng, J.; Denisov, S. P.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Devetak, E.; Deviveiros, P. O.; Dewhurst, A.; DeWilde, B.; Dhaliwal, S.; Dhullipudi, R.; Di Ciaccio, A.; Di Ciaccio, L.; Di Girolamo, A.; Di Girolamo, B.; Di Luise, S.; Di Mattia, A.; Di Micco, B.; Di Nardo, R.; Di Simone, A.; Di Sipio, R.; Diaz, M. A.; Diblen, F.; Diehl, E. B.; Dietl, H.; Dietrich, J.; Dietzsch, T. A.; Diglio, S.; Dindar Yagci, K.; Dingfelder, J.; Dionisi, C.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djilkibaev, R.; Djobava, T.; do Vale, M. A. B.; Do Valle Wemans, A.; Doan, T. K. O.; Dobbs, M.; Dobinson, R.; Dobos, D.; Dobson, E.; Dobson, M.; Dodd, J.; Dogan, O. B.; Doglioni, C.; Doherty, T.; Doi, Y.; Dolejsi, J.; Dolenc, I.; Dolezal, Z.; Dolgoshein, B. A.; Dohmae, T.; Donadelli, M.; Donega, M.; Donini, J.; Dopke, J.; Doria, A.; Dos Anjos, A.; Dosil, M.; Dotti, A.; Dova, M. T.; Dowell, J. D.; Doxiadis, A. D.; Doyle, A. T.; Drasal, Z.; Drees, J.; Dressnandt, N.; Drevermann, H.; Driouichi, C.; Dris, M.; Drohan, J. G.; Dubbert, J.; Dubbs, T.; Dube, S.; Duchovni, E.; Duckeck, G.; Dudarev, A.; Dudziak, F.; Dührssen, M.; Duerdoth, I. P.; Duflot, L.; Dufour, M.-A.; Dunford, M.; Yildiz, H. Duran; Duxfield, R.; Dwuznik, M.; Dydak, F.; Dzahini, D.; Düren, M.; Ebenstein, W. L.; Ebke, J.; Eckert, S.; Eckweiler, S.; Edmonds, K.; Edwards, C. A.; Ehrenfeld, W.; Ehrich, T.; Eifert, T.; Eigen, G.; Einsweiler, K.; Eisenhandler, E.; Ekelof, T.; El Kacimi, M.; Ellert, M.; Elles, S.; Ellinghaus, F.; Ellis, K.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Ely, R.; Emeliyanov, D.; Engelmann, R.; Engl, A.; Epp, B.; Eppig, A.; Erdmann, J.; Ereditato, A.; Eriksson, D.; Ernst, J.; Ernst, M.; Ernwein, J.; Errede, D.; Errede, S.; Ertel, E.; Escalier, M.; Escobar, C.; Espinal Curull, X.; Esposito, B.; Etienne, F.; Etienvre, A. I.; Etzion, E.; Evangelakou, D.; Evans, H.; Fabbri, L.; Fabre, C.; Facius, K.; Fakhrutdinov, R. M.; Falciano, S.; Falou, A. C.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farley, J.; Farooque, T.; Farrington, S. M.; Farthouat, P.; Fasching, D.; Fassnacht, P.; Fassouliotis, D.; Fatholahzadeh, B.; Favareto, A.; Fayard, L.; Fazio, S.; Febbraro, R.; Federic, P.; Fedin, O. L.; Fedorko, I.; Fedorko, W.; Fehling-Kaschek, M.; Feligioni, L.; Fellmann, D.; Felzmann, C. U.; Feng, C.; Feng, E. J.; Fenyuk, A. 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R.; Haefner, P.; Hahn, F.; Haider, S.; Hajduk, Z.; Hakobyan, H.; Haller, J.; Hamacher, K.; Hamal, P.; Hamilton, A.; Hamilton, S.; Han, H.; Han, L.; Hanagaki, K.; Hance, M.; Handel, C.; Hanke, P.; Hansen, C. J.; Hansen, J. R.; Hansen, J. B.; Hansen, J. D.; Hansen, P. H.; Hansson, P.; Hara, K.; Hare, G. A.; Harenberg, T.; Harper, D.; Harrington, R. D.; Harris, O. M.; Harrison, K.; Hartert, J.; Hartjes, F.; Haruyama, T.; Harvey, A.; Hasegawa, S.; Hasegawa, Y.; Hassani, S.; Hatch, M.; Hauff, D.; Haug, S.; Hauschild, M.; Hauser, R.; Havranek, M.; Hawes, B. M.; Hawkes, C. M.; Hawkings, R. J.; Hawkins, D.; Hayakawa, T.; Hayden, D.; Hayward, H. S.; Haywood, S. J.; Hazen, E.; He, M.; Head, S. J.; Hedberg, V.; Heelan, L.; Heim, S.; Heinemann, B.; Heisterkamp, S.; Helary, L.; Heldmann, M.; Heller, M.; Hellman, S.; Helsens, C.; Henderson, R. C. W.; Henke, M.; Henrichs, A.; Correia, A. M. 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C.; Koenig, S.; Köpke, L.; Koetsveld, F.; Koevesarki, P.; Koffas, T.; Koffeman, E.; Kohn, F.; Kohout, Z.; Kohriki, T.; Koi, T.; Kokott, T.; Kolachev, G. M.; Kolanoski, H.; Kolesnikov, V.; Koletsou, I.; Koll, J.; Kollar, D.; Kollefrath, M.; Kolya, S. D.; Komar, A. A.; Komaragiri, J. R.; Kondo, T.; Kono, T.; Kononov, A. I.; Konoplich, R.; Konstantinidis, N.; Kootz, A.; Koperny, S.; Kopikov, S. V.; Korcyl, K.; Kordas, K.; Koreshev, V.; Korn, A.; Korol, A.; Korolkov, I.; Korolkova, E. V.; Korotkov, V. A.; Kortner, O.; Kortner, S.; Kostyukhin, V. V.; Kotamäki, M. J.; Kotov, S.; Kotov, V. M.; Kourkoumelis, C.; Kouskoura, V.; Koutsman, A.; Kowalewski, R.; Kowalski, H.; Kowalski, T. Z.; Kozanecki, W.; Kozhin, A. S.; Kral, V.; Kramarenko, V. A.; Kramberger, G.; Krasel, O.; Krasny, M. W.; Krasznahorkay, A.; Kraus, J.; Kreisel, A.; Krejci, F.; Kretzschmar, J.; Krieger, N.; Krieger, P.; Kroeninger, K.; Kroha, H.; Kroll, J.; Kroseberg, J.; Krstic, J.; Kruchonak, U.; Krüger, H.; Krumshteyn, Z. 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E.; Taylor, G. N.; Taylor, W.; Castanheira, M. Teixeira Dias; Teixeira-Dias, P.; Temming, K. K.; Ten Kate, H.; Teng, P. K.; Terada, S.; Terashi, K.; Terron, J.; Terwort, M.; Testa, M.; Teuscher, R. J.; Tevlin, C. M.; Thadome, J.; Therhaag, J.; Theveneaux-Pelzer, T.; Thioye, M.; Thoma, S.; Thomas, J. P.; Thompson, E. N.; Thompson, P. D.; Thompson, P. D.; Thompson, A. S.; Thomson, E.; Thomson, M.; Thun, R. P.; Tic, T.; Tikhomirov, V. O.; Tikhonov, Y. A.; Timmermans, C. J. W. P.; Tipton, P.; Tique Aires Viegas, F. J.; Tisserant, S.; Tobias, J.; Toczek, B.; Todorov, T.; Todorova-Nova, S.; Toggerson, B.; Tojo, J.; Tokár, S.; Tokunaga, K.; Tokushuku, K.; Tollefson, K.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, G.; Tonoyan, A.; Topfel, C.; Topilin, N. D.; Torchiani, I.; Torrence, E.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Traynor, D.; Trefzger, T.; Treis, J.; Tremblet, L.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Trinh, T. N.; Tripiana, M. 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G.; Zhu, H.; Zhu, Y.; Zhuang, X.; Zhuravlov, V.; Zieminska, D.; Zimmermann, R.; Zimmermann, S.; Zimmermann, S.; Ziolkowski, M.; Zitoun, R.; Živković, L.; Zmouchko, V. V.; Zobernig, G.; Zoccoli, A.; Zolnierowski, Y.; Zsenei, A.; zur Nedden, M.; Zutshi, V.; Zwalinski, L.
2011-07-01
Results are presented of a search for particles decaying into final states with significant missing transverse momentum and exactly two identical flavour leptons ( e, μ) of opposite charge in sqrt{s}=7 TeV collisions at the Large Hadron Collider. This channel is particularly sensitive to supersymmetric particle cascade decays producing flavour correlated lepton pairs. Flavour uncorrelated backgrounds are subtracted using a sample of opposite flavour lepton pair events. Observation of an excess beyond Standard Model expectations following this subtraction procedure would offer one of the best routes to measuring the masses of supersymmetric particles. In a data sample corresponding to an integrated luminosity of 35 pb-1 no such excess is observed. Model-independent limits are set on the contribution to these final states from supersymmetry and are used to exclude regions of a phenomenological supersymmetric parameter space.
Double Molecular Photoswitch Driven by Light and Collisions
NASA Astrophysics Data System (ADS)
Bull, James N.; Scholz, Michael S.; Carrascosa, Eduardo; da Silva, Gabriel; Bieske, Evan J.
2018-06-01
The shapes of many molecules can be transformed by light or heat. Here we investigate collision- and photon-induced interconversions of E E , E Z , and Z Z isomers of the isolated Congo red (CR) dianion, a double molecular switch containing two - N ═ N - azo groups, each of which can have the E or Z configuration. We find that collisional activation of CR dianions drives a one-way Z Z →E Z →E E cascade towards the lowest-energy isomer, whereas the absorption of a single photon over the 270-600 nm range can switch either azo group from E to Z or Z to E , driving the CR dianion to lower- or higher-energy forms. The experimental results, which are interpreted with the aid of calculated statistical isomerization rates, indicate that photoisomerization of CR in the gas phase involves a passage through conical intersection seams linking the excited and ground state potential energy surfaces rather than through isomerization on the ground state potential energy surface following internal conversion.
Solar wind charge exchange in laboratory - Observation of forbidden X-ray transitions
NASA Astrophysics Data System (ADS)
Numadate, Naoki; Shimaya, Hirofumi; Ishida, Takuya; Okada, Kunihiro; Nakamura, Nobuyuki; Tanuma, Hajime
2017-10-01
We have reproduced solar wind charge exchange collisions of hydrogen-like O7+ ions with He gas at collision energies of 42 keV in the laboratory and observed the forbidden transition of 1s21S0 -1s2s 3S1 in helium-like O6+ ions produced by single electron capture. The measured soft X-ray spectrum had a peak at 560 eV which corresponds to the energy of the forbidden 1s21S0 -1s2s 3S1 transition in the O6+ ion, and a reasonable energy difference between peak positions of the forbidden and resonance lines was found, which ensured that we succeeded in observing the forbidden transition of O6+ ions. The dominant electron capture level in the collision of O7+ ions with He can be estimated to be a principal quantum number n = 4 by the classical over barrier model and the two-center atomic orbital close coupling method. After the charge exchange, the population of the 1s2s state becomes large due to cascade transitions from the higher excited states, so the long-lived forbidden transition to the 1s21S0 ground state is one of main features observed in the charge exchange spectra.
Onset of chaos in a single-phase power electronic inverter.
Avrutin, Viktor; Mosekilde, Erik; Zhusubaliyev, Zhanybai T; Gardini, Laura
2015-04-01
Supported by experiments on a power electronic DC/AC converter, this paper considers an unusual transition from the domain of stable periodic dynamics (corresponding to the desired mode of operation) to chaotic dynamics. The behavior of the converter is studied by means of a 1D stroboscopic map derived from a non-autonomous ordinary differential equation with discontinuous right-hand side. By construction, this stroboscopic map has a high number of border points. It is shown that the onset of chaos occurs stepwise, via irregular cascades of different border collisions, some of which lead to bifurcations while others do not.
Wan Chan Tseung, H; Ma, J; Beltran, C
2015-06-01
Very fast Monte Carlo (MC) simulations of proton transport have been implemented recently on graphics processing units (GPUs). However, these MCs usually use simplified models for nonelastic proton-nucleus interactions. Our primary goal is to build a GPU-based proton transport MC with detailed modeling of elastic and nonelastic proton-nucleus collisions. Using the cuda framework, the authors implemented GPU kernels for the following tasks: (1) simulation of beam spots from our possible scanning nozzle configurations, (2) proton propagation through CT geometry, taking into account nuclear elastic scattering, multiple scattering, and energy loss straggling, (3) modeling of the intranuclear cascade stage of nonelastic interactions when they occur, (4) simulation of nuclear evaporation, and (5) statistical error estimates on the dose. To validate our MC, the authors performed (1) secondary particle yield calculations in proton collisions with therapeutically relevant nuclei, (2) dose calculations in homogeneous phantoms, (3) recalculations of complex head and neck treatment plans from a commercially available treatment planning system, and compared with (GEANT)4.9.6p2/TOPAS. Yields, energy, and angular distributions of secondaries from nonelastic collisions on various nuclei are in good agreement with the (GEANT)4.9.6p2 Bertini and Binary cascade models. The 3D-gamma pass rate at 2%-2 mm for treatment plan simulations is typically 98%. The net computational time on a NVIDIA GTX680 card, including all CPU-GPU data transfers, is ∼ 20 s for 1 × 10(7) proton histories. Our GPU-based MC is the first of its kind to include a detailed nuclear model to handle nonelastic interactions of protons with any nucleus. Dosimetric calculations are in very good agreement with (GEANT)4.9.6p2/TOPAS. Our MC is being integrated into a framework to perform fast routine clinical QA of pencil-beam based treatment plans, and is being used as the dose calculation engine in a clinically applicable MC-based IMPT treatment planning system. The detailed nuclear modeling will allow us to perform very fast linear energy transfer and neutron dose estimates on the GPU.
Ab initio treatment of ion-induced charge transfer dynamics of isolated 2-deoxy-D-ribose.
Bacchus-Montabonel, Marie-Christine
2014-08-21
Modeling-induced radiation damage in biological systems, in particular, in DNA building blocks, is of major concern in cancer therapy studies. Ion-induced charge-transfer dynamics may indeed be involved in proton and hadrontherapy treatments. We have thus performed a theoretical approach of the charge-transfer dynamics in collision of C(4+) ions and protons with isolated 2-deoxy-D-ribose in a wide collision energy range by means of ab initio quantum chemistry molecular methods. The comparison of both projectile ions has been performed with regard to previous theoretical and experimental results. The charge transfer appears markedly less efficient with the 2-deoxy-D-ribose target than that with pyrimidine nucleobases, which would induce an enhancement of the fragmentation process in agreement with experimental measurements. The mechanism has been analyzed with regard to inner orbital excitations, and qualitative tendencies have been pointed out for studies on DNA buiding block damage.
Data fusion of multi-scale representations for structural damage detection
NASA Astrophysics Data System (ADS)
Guo, Tian; Xu, Zili
2018-01-01
Despite extensive researches into structural health monitoring (SHM) in the past decades, there are few methods that can detect multiple slight damage in noisy environments. Here, we introduce a new hybrid method that utilizes multi-scale space theory and data fusion approach for multiple damage detection in beams and plates. A cascade filtering approach provides multi-scale space for noisy mode shapes and filters the fluctuations caused by measurement noise. In multi-scale space, a series of amplification and data fusion algorithms are utilized to search the damage features across all possible scales. We verify the effectiveness of the method by numerical simulation using damaged beams and plates with various types of boundary conditions. Monte Carlo simulations are conducted to illustrate the effectiveness and noise immunity of the proposed method. The applicability is further validated via laboratory cases studies focusing on different damage scenarios. Both results demonstrate that the proposed method has a superior noise tolerant ability, as well as damage sensitivity, without knowing material properties or boundary conditions.
NASA Technical Reports Server (NTRS)
Kessler, D. J.; Cour-Palais, B. G.; Taylor, R. E.; Landry, P. M.
1980-01-01
Collisions in earth orbital space between operational payloads and various forms of space debris (nonoperational payloads, nonfunctional mission-related objects and fragments resulting from collisions and explosions) are discussed and possible means of avoiding them are considered. From 10,000 to 15,000 objects are estimated to be in earth orbital space, most of which represent spacecraft fragments and debris too small to be detected and tracked by earth-based sensors, and it is considered likely that some of them will be or have already been involved in direct collisions with the ever increasing number of operational satellites and space stations. Means of protecting proposed large space structures and smaller spacecraft from significant damage by larger space objects, particularly in the 400-4000 km altitude range where most debris occurs, include structural redundancy and the double shielding of sensitive components. Other means of collision avoidance are the collection or relocation of satellites, rocket bodies and other objects by the Space Shuttle, the prevention of explosions and the disposal of spent rocket parts by reentry. Finally, a management structure would be required to administer guidelines for the prevention and elimination of space debris.
Rosenblat, Gennady; Meretski, Shai; Segal, Joseph; Tarshis, Mark; Schroeder, Avi; Zanin-Zhorov, Alexandra; Lion, Gilead; Ingber, Arieh; Hochberg, Malka
2011-05-01
Exposing skin to ultraviolet (UV) radiation contributes to photoaging and to the development of skin cancer by DNA lesions and triggering inflammatory and other harmful cellular cascades. The present study tested the ability of unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, to reduce UVB-induced damage and inflammation in skin. Introducing PFA to keratinocytes prior to their exposure to UVB exerted a protective effect, increasing cell viability, decreasing the secretion of IL-6 and PGE(2), and enhancing DNA repair. In human skin explants, treating with PFA reduced significantly UV-induced cellular damage. These results support the idea that PFA can play an important role as a photo-protective agent in UV-induced skin damage.
A new technique for ground simulation of hypervelocity debris
NASA Astrophysics Data System (ADS)
Roybal, R.; Shively, J.; Stein, C.; Miglionico, C.; Robertson, R.
1995-02-01
A series of hypervelocity damage experiments were preformed on spacecraft materials. These experiments employed a technique which accelerates micro flyer plates simulating space debris traveling at 3 to 8 km/sec. The apparatus used to propel the micro flyer plates was compact and fit well into a space environmental chamber equipped with instrumentation capable of analyzing the vapor ejected from the sample. Mechanical damage to the sample was also characterized using optical and scanning electron microscpopy. Data for this work was obtained from hypervelocity impacts on a polysulfone resin and a graphite polysulfone composite. Polysulfone was selected because it was flown on the Long Duration Exposure Facility (LDEF) which spent several years in low earth orbit (LEO). Chemistry of the vapor produced by the impact was analyzed with a time of flight mass spectrometer, (TOFMS). This represents the first time that ejected vapors from hypervelocity collisions were trapped and analyzed with a mass spectrometer. With this approach we are able to study changes in the vapor chemistry as a function of time after impact, obtain a velocity measurement of the vapor, and estimate a temperature of the surface at time of impact using dynamic gas equations. Samples of the vapor plume may be captured and examined by transmission electron microscopy. Studies were also conducted to determine mechanical damage to a graphite polysulfone composite and a polysulfone resin. Impact craters were examined under optical and scanning electron microscopes. The collision craters in the matrix were typical of those shown in conventional shock experiments. However, the hypervelocity collisions with the graphite polysulfone composite were remarkably different than those with the resin.
NASA Astrophysics Data System (ADS)
Hand, D. H.
1981-01-01
The test vehicles were impacted tested for compliance with FMVSS 212/219/301-75. As a parallel nonconflicting effort, the test vehicles were instrumented with accelerometers to measure vehicle accelerator resultants.
46 CFR 10.229 - Issuance of duplicate merchant mariner credentials.
Code of Federal Regulations, 2013 CFR
2013-10-01
... replaced credential(s). The duplicate issued will be in the form of an MMC. Until April 15, 2014, if a... charge. The term “other casualty” includes any damage to a ship caused by collision, explosion, tornado...
46 CFR 10.229 - Issuance of duplicate merchant mariner credentials.
Code of Federal Regulations, 2012 CFR
2012-10-01
... replaced credential(s). The duplicate issued will be in the form of an MMC. Until April 15, 2014, if a... charge. The term “other casualty” includes any damage to a ship caused by collision, explosion, tornado...
Evaluation of a buried cable roadside animal detection system.
DOT National Transportation Integrated Search
2015-06-01
Animal-vehicle collisions (AVC) are a concern for departments of transportation as they translate into hundreds of : human fatalities and billions of dollars in property damage each year. A recently published report states that the Virginia : Departm...
Zhao, Na; Wu, Baoyan; Hu, Xianglong; Xing, Da
2017-10-01
Stimuli-responsive nanoparticles with multiple therapeutic/diagnostic functions are highly desirable for effective tumor treatment. Herein novel caspase-3 responsive functionalized upconversion nanoparticles (CFUNs) were fabricated with three-in-one functional integration: near-infrared (NIR) triggered photodynamic damage along with caspase-3 activation, subsequent caspase-3 responsive drug release, and cascade chemotherapeutic activation. CFUNs were formulated from the self-assembly of caspase-3 responsive doxorubicin (DOX) prodrug tethered with DEVD peptide (DEVD-DOX), upconversion nanoparticles (UCNP), a photosensitizer (pyropheophorbide-a methyl ester, MPPa), and tumor-targeting cRGD-PEG-DSPE to afford multifunctional CFUNs, MPPa/UCNP-DEVD-DOX/cRGD. Upon cellular uptake and NIR irradiation, the visible light emission of UCNP could excite MPPa to produce reactive oxygen species for photodynamic therapy (PDT) along with the activation of caspase-3, which further cleaved DEVD peptide to release DOX within tumor cells, thus accomplishing NIR-triggered PDT and cascade chemotherapy. CFUNs presented silent therapeutic potency and negligible cytotoxicity in the dark, whereas in vitro and in vivo experiments demonstrated the NIR-triggered cascade therapeutic activation and tumor inhibition due to consecutive PDT and chemotherapy. Current NIR-activated cascade tumor therapy with two distinct mechanisms is significantly favorable to overcome multidrug resistance and tumor heterogeneity for persistent tumor treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.
Ravi, Koustuban; Schimpf, Damian N; Kärtner, Franz X
2016-10-31
The use of laser pulse sequences to drive the cascaded difference frequency generation of high energy, high peak-power and multi-cycle terahertz pulses in cryogenically cooled (100 K) periodically poled Lithium Niobate is proposed and studied. Detailed simulations considering the coupled nonlinear interaction of terahertz and optical waves (or pump depletion), show that unprecedented optical-to-terahertz energy conversion efficiencies > 5%, peak electric fields of hundred(s) of mega volts/meter at terahertz pulse durations of hundred(s) of picoseconds can be achieved. The proposed methods are shown to circumvent laser induced damage limitations at Joule-level pumping by 1µm lasers to enable multi-cycle terahertz sources with pulse energies > 10 milli-joules. Various pulse sequence formats are proposed and analyzed. Numerical calculations for periodically poled structures accounting for cascaded difference frequency generation, self-phase-modulation, cascaded second harmonic generation and laser induced damage are introduced. The physics governing terahertz generation using pulse sequences in this high conversion efficiency regime, limitations and practical considerations are discussed. It is shown that varying the poling period along the crystal length and further reduction of absorption can lead to even higher energy conversion efficiencies >10%. In addition to numerical calculations, an analytic formulation valid for arbitrary pulse formats and closed-form expressions for important cases are presented. Parameters optimizing conversion efficiency in the 0.1-1 THz range, the corresponding peak electric fields, crystal lengths and terahertz pulse properties are furnished.
Tang, Youming; Cao, Libo; Kan, Steven
2014-01-01
Objectives To examine the damage location distribution of five main body region injuries of maximum abbreviated injury score (MAIS) 3–6 injured occupants for nearside struck vehicle in front-to-side impact crashes. Design and setting MAIS 3–6 injured occupants information was extracted from the US-National Automotive Sampling System/Crashworthiness Data System in the year 2007; it included the head/face/neck, chest, pelvis, upper extremity and lower extremity. Struck vehicle collision damage was classified in a three-dimensional system according to the J224 Collision Deformation Classification of SAE Surface Vehicle Standard. Participants Nearside occupants seated directly adjacent to the struck side of the vehicle with MAIS 3–6 injured, in light truck vehicles–passenger cars (LTV–PC) side impact crashes. Outcome measures Distribution of MAIS 3–6 injured occupants by body regions and specific location of damage (lateral direction, horizontal direction and vertical direction) were examined. Injury risk ratio was also assessed. Results The lateral crush zone contributed to MAIS 3–6 injured occupants (n=705) and 50th centile injury risks when extended into zone 3. When the crush extended to zone 4, the injury risk ratio of MAIS 3–6 injured occupants approached 81%. The horizontal crush zones contributing to the highest injury risk ratio of MAIS 3–6 occupants were zones ‘D’ and ‘Y’, and the injury risk ratios were 25.4% and 36.9%, respectively. In contrast, the lowest injury risk ratio was 5.67% caused by zone ‘B’. The vertical crush zone which contributed to the highest injury risk ratio of MAIS 3–6 occupants was zone ‘E’, whose injury risk ratio was 58%. In contrast, the lowest injury risk ratio was 0.14% caused by zone ‘G+M’. Conclusions The highest injury risk ratio of MAIS 3–6 injured occupants caused by crush intrusion between 40 and 60 cm in LTV–PC nearside impact collisions and the damage region of the struck vehicle was in the zones ‘E’ and ‘Y’. PMID:24812190
Discovery of a novel aquaporin ZmPIP2-8 from southern corn rootworm infested maize
USDA-ARS?s Scientific Manuscript database
A common paradigm of infestation by chewing insects is a jasmonic acid (JA) cascade that results in the induction of JA responsive genes. However examination of several maize genes induced by Southern corn rootworm (SCR) infestation, an insect that chews into and significantly damages maize roots, ...
Predicting neutron damage using TEM with in situ ion irradiation and computer modeling
NASA Astrophysics Data System (ADS)
Kirk, Marquis A.; Li, Meimei; Xu, Donghua; Wirth, Brian D.
2018-01-01
We have constructed a computer model of irradiation defect production closely coordinated with TEM and in situ ion irradiation of Molybdenum at 80 °C over a range of dose, dose rate and foil thickness. We have reexamined our previous ion irradiation data to assign appropriate error and uncertainty based on more recent work. The spatially dependent cascade cluster dynamics model is updated with recent Molecular Dynamics results for cascades in Mo. After a careful assignment of both ion and neutron irradiation dose values in dpa, TEM data are compared for both ion and neutron irradiated Mo from the same source material. Using the computer model of defect formation and evolution based on the in situ ion irradiation of thin foils, the defect microstructure, consisting of densities and sizes of dislocation loops, is predicted for neutron irradiation of bulk material at 80 °C and compared with experiment. Reasonable agreement between model prediction and experimental data demonstrates a promising direction in understanding and predicting neutron damage using a closely coordinated program of in situ ion irradiation experiment and computer simulation.
Energy loss in vehicle collisions from permanent deformation: an extension of the `Triangle Method'
NASA Astrophysics Data System (ADS)
Vangi, Dario; Begani, Filippo
2013-06-01
The paper presents an extension of the 'Triangle Method', to evaluate the energy loss in road accidents. The improvement of the method allows to evaluate the energy loss by both the colliding vehicles in car to car impacts, considering the main possible configurations of accident. The limits of applicability of the method are those of the Campbell's method [K.E. Campbell, Energy basis for collision severity, SAE paper 740565, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1974; A.G. Fonda, Principles of crush energy determination, SAE 1999-01-0106, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1999; N.S. Tumbas and R.A. Smith, Measurement protocol for quantifying vehicle damage from an energy basis point of view, SAE paper 880072, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1988; G.A. Nystrom, G. Kost, and S.M. Werner, Stiffness parameters for vehicle collision analysis, SAE paper 910119, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1991; J.A. Neptune, G.Y. Blair, and J.E. Flynn, A method for quantifying vehicle crush stiffness coefficients, SAE paper 920607, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1992]. The advantage over the usual methods are that the method does not require the knowledge of the stiffness of the vehicles and only two parameters are needed to define the damage geometry. The latter can be easily evaluated by visual inspection on a suitable photographical documentation of the damages, without the need to perform any direct measurement on the vehicles. Furthermore, the method can be used also in the very frequent cases in which some of the damage data about one of the vehicles are missing or in accidents involving lateral parts of the vehicle as zones near the wheels or the front, that have different behaviour from that tested in the classical crash tests. The error analysis developed shows that the errors due to the application of the extended method are negligible and fall in the range generally considered acceptable in road accident reconstruction.
Asteroid collisions: Target size effects and resultant velocity distributions
NASA Technical Reports Server (NTRS)
Ryan, Eileen V.
1993-01-01
To study the dynamic fragmentation of rock to simulate asteroid collisions, we use a 2-D, continuum damage numerical hydrocode which models two-body impacts. This hydrocode monitors stress wave propagation and interaction within the target body, and includes a physical model for the formation and growth of cracks in rock. With this algorithm we have successfully reproduced fragment size distributions and mean ejecta speeds from laboratory impact experiments using basalt, and weak and strong mortar as target materials. Using the hydrocode, we have determined that the energy needed to fracture a body has a much stronger dependence on target size than predicted from most scaling theories. In addition, velocity distributions obtained indicate that mean ejecta speeds resulting from large-body collisions do not exceed escape velocities.
Medvedeva, Nataly; Papper, Vladislav; Likhtenshtein, Gertz I
2005-09-21
Measurements of active encounters between molecules in native membranes containing ingredients, including proteins, are of prime importance. To estimate rare encounters in a high range of rate constants (rate coefficients) and distances between interacting molecules in membranes, a cascade of photochemical reactions for molecules diffusing in multilamellar liposomes was investigated. The sensitised cascade triplet cis-trans photoisomerisation of the excited stilbene involves the use of a triplet sensitiser (Erythrosin B), a photochrome stilbene-derivative probe (4-dimethylamino-4'-aminostilbene) exhibiting the phenomenon of trans-cis photoisomerisation, and nitroxide radicals (5-doxyl stearic acid) to quench the excited triplet state of the sensitiser. Measurement of the phosphorescence lifetime of Erythrosin B and the fluorescence enhancement of the stilbene-derivative photochrome probe, at various concentrations of the nitroxide probe, made it possible to calculate the quenching rate constant k(q)= 1.1 x 10(15) cm2 M(-1) s(-1) and the rate constant of the triplet-triplet energy transfer between the sensitiser and stilbene probe k(T)= 1.0 x 10(12) cm2 M(-1) s(-1). These values, together with the data on diffusion rate constant, obtained by methods utilising various theoretical characteristic times of about seven orders of magnitude and the experimental rate constants of about five orders of magnitude, were found to be in good agreement with the advanced theory of diffusion-controlled reactions in two dimensions. Because the characteristic time of the proposed cascade method is relatively large (0.1 s), it is possible to follow rare collisions between molecules and free radicals in model and biological membranes with a very sensitive fluorescence spectroscopy technique, using a relatively low concentration of probes.
Elliptic flow of identified hadrons in Pb-Pb collisions at $$ \\sqrt{s_{\\mathrm{NN}}}=2.76 $$ TeV
Abelev, B.; Adam, J.; Adamová, D.; ...
2015-06-29
Here, the elliptic flow coefficient (v 2) of identified particles in Pb-Pb collisions at √s NN =2.76 TeV was measured with the ALICE detector at the Large Hadron Collider (LHC). The results were obtained with the Scalar Product method, a two-particle correlation technique, using a pseudo-rapidity gap of |Δη| > 0.9 between the identified hadron under study and the reference particles. The v 2 is reported for π ±, K ±, K S 0, p+p¯, Φ, Λ+Λ¯, Ξ –+Ξ¯+ and Ω –+Ω ¯+ in several collision centralities. In the low transverse momentum (p T) region, p T < 3 GeV/c,more » v 2(p T) exhibits a particle mass dependence consistent with elliptic flow accompanied by the transverse radial expansion of the system with a common velocity field. The experimental data for π± and the combined K ± and K S 0 results, are described fairly well by hydrodynamic calculations coupled to a hadronic cascade model (VISHNU) for central collisions. However, the same calculations fail to reproduce the v 2(p T) for p+p¯, Φ, Λ+Λ¯ and Ξ –+Ξ ¯+. For transverse momentum values larger than about 3 GeV/c, particles tend to group according to their type, i.e. mesons and baryons. The present measurements exhibit deviations from the number of constituent quark (NCQ) scaling at the level of ±20% for p T > 3 GeV/c.« less
Repair of Budd Pioneer Coach car crush zones
DOT National Transportation Integrated Search
2007-05-01
The research team conducted a project to repair cars for use in a full-scale train-to-train collision test with crash energy management systems. The two cars had been damaged in previous dynamic tests. Several components required replacement, and som...
Electron Impact Excitation-Ionization of Molecules
NASA Astrophysics Data System (ADS)
Ali, Esam Abobakr A.
In the last few decades, the study of atomic collisions by electron-impact has made significant advances. The most difficult case to study is electron impact ionization of molecules for which many approximations have to be made and the validity of these approximations can only be checked by comparing with experiment. In this thesis, I have examined the Molecular three-body distorted wave (M3DW) or Molecular four-body distorted wave (M4DW) approximations for electron-impact ionization. These models use a fully quantum mechanical approach where all particles are treated quantum mechanically and the post collision interaction (PCI) is treated to all orders of perturbation. These electron impact ionization collisions play central roles in the physics and chemistry of upper atmosphere, biofuel, the operation of discharges and lasers, radiation induced damage in biological material like damage to DNA by secondary electrons, and plasma etching processes. For the M3DW model, I will present results for electron impact single ionization of small molecules such as Water, Ethane, and Carbon Dioxide and the much larger molecules Tetrahydrofuran, phenol, furfural, 1-4 Benzoquinone. I will also present results for the four-body problem in which there are two target electrons involved in the collision. M4DW results will be presented for dissociative excitation-ionization of orientated D2. I will show that M4DW calculations using a variational wave function for the ground state that included s- and p- orbital states give better agreement to the experimental measurements than a ground state approximated as a product of two 1s-type Dyson orbitals.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Pearson, Walter H.; Al-Ghais, Saif M.; Neff, Jerry M.
1998-12-01
Historically, about half the oil transported through the global marine environment has come through the Arabian Gulf and the annual input of oil to the gulf's marine environment is skewed toward sources connected with marine transport. As a case study, we assess the damages from an oil spill caused by a collision between the crude oil tankers Baynuna and the Seki on 30 March 1994. The collision released approximately 16,000 metric tons (MT) of light Iranian crude oil into the coastal waters of the Emirate of Fujairah, United Arab Emirates. Under the sponsorship of the government of Fujairah, we analyzemore » the effects on commercial fisheries and marine environment of Fujairah resulting from the spill. This analysis was the first comprehensive natural resource damage assessment conducted in this area. The major difficulty was to establish the economic damages associated with the environmental contamination and fisheries declines. We adapt an established compensation schedule to the UA E situation. Information on the amount and type of oil spilled, the amount of oil recovered, the season, the habitats oiled, the resources exposed, and the sensitivity of the resources is then used to establish the conic value of losses associated with environmental contamination and fisheries decline.« less
NASA Astrophysics Data System (ADS)
Itoh, Makoto; Fujiwara, Yusuke; Inagaki, Toshiyuki
This paper discusses driver's behavioral changes as a result of driver's use of an automatic brake system for preventing a rear-end collision from occurring. Three types of automatic brake systems are investigated in this study. Type 1 brake system applies a strong automatic brake when a collision is very imminent. Type 2 brake system initiates brake operation softly when a rear-end crash may be anticipated. Types 1 and 2 are for avoidance of a collision. Type 3 brake system, on the other hand, applies a strong automatic brake to reduce the damage when a collision can not be avoided. An experiment was conducted with a driving simulator in order to analyze the driver's possible behavioral changes. The results showed that the time headway (THW) during car following phase was reduced by use of an automatic brake system of any type. The inverse of time to collision (TTC), which is an index of the driver's brake timing, increased by use of Type 1 brake system when the deceleration rate of the lead vehicle was relatively low. However, the brake timing did not change when the drivers used Type 2 or 3 brake system. As a whole, dangerous behavioral changes, such as overreliance on a brake system, were not observed for either type of brake system.
Zhang, Linshuai; Guo, Shuxiang; Yu, Huadong; Song, Yu; Tamiya, Takashi; Hirata, Hideyuki; Ishihara, Hidenori
2018-02-23
The robot-assisted catheter system can increase operating distance thus preventing the exposure radiation of the surgeon to X-ray for endovascular catheterization. However, few designs have considered the collision protection between the catheter tip and the vessel wall. This paper presents a novel catheter operating system based on tissue protection to prevent vessel puncture caused by collision. The integrated haptic interface not only allows the operator to feel the real force feedback, but also combines with the newly proposed collision protection mechanism (CPM) to mitigate the collision trauma. The CPM can release the catheter quickly when the measured force exceeds a certain threshold, so as to avoid the vessel puncture. A significant advantage is that the proposed mechanism can adjust the protection threshold in real time by the current according to the actual characteristics of the blood vessel. To verify the effectiveness of the tissue protection by the system, the evaluation experiments in vitro were carried out. The results show that the further collision damage can be effectively prevented by the CPM, which implies the realization of relative safe catheterization. This research provides some insights into the functional improvements of safe and reliable robot-assisted catheter systems.
NASA Astrophysics Data System (ADS)
Warrier, M.; Bhardwaj, U.; Hemani, H.; Schneider, R.; Mutzke, A.; Valsakumar, M. C.
2015-12-01
We report on molecular Dynamics (MD) simulations carried out in fcc Cu and bcc W using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code to study (i) the statistical variations in the number of interstitials and vacancies produced by energetic primary knock-on atoms (PKA) (0.1-5 keV) directed in random directions and (ii) the in-cascade cluster size distributions. It is seen that around 60-80 random directions have to be explored for the average number of displaced atoms to become steady in the case of fcc Cu, whereas for bcc W around 50-60 random directions need to be explored. The number of Frenkel pairs produced in the MD simulations are compared with that from the Binary Collision Approximation Monte Carlo (BCA-MC) code SDTRIM-SP and the results from the NRT model. It is seen that a proper choice of the damage energy, i.e. the energy required to create a stable interstitial, is essential for the BCA-MC results to match the MD results. On the computational front it is seen that in-situ processing saves the need to input/output (I/O) atomic position data of several tera-bytes when exploring a large number of random directions and there is no difference in run-time because the extra run-time in processing data is offset by the time saved in I/O.
Monitoring Mount Baker Volcano
Malone, S.D.; Frank, D.
1976-01-01
Hisotrically active volcanoes in the conterminous United States are restricted to the Cascade Range and extend to the Cascade Range and extend from Mount Baker near the Canadian border to Lassen Peak in northern California. Since 1800 A.D, most eruptive activity has been on a relatively small scale and has not caused loss of life or significant property damage. However, future volcanism predictably will have more serious effects because of greatly increased use of land near volcanoes during the present century. (See "Appraising Volcanic Hazards of the Cascade Range of the Northwestern United States," Earthquake Inf. Bull., Sept.-Oct. 1974.) The recognition an impending eruption is highly important in order to minimize the potential hazard to people and property. Thus, a substantial increase in hydrothermal activity at Mount Baker in March 1975 ( see "Mount Baker Heating Up," July-Aug. 1975 issue) was regarded as a possible first signal that an eruption might occur, and an intensive monitoring program was undertaken.
Molecular dynamics study of Al and Ni 3Al sputtering by Al clusters bombardment
NASA Astrophysics Data System (ADS)
Zhurkin, Eugeni E.; Kolesnikov, Anton S.
2002-06-01
The sputtering of Al and Ni 3Al (1 0 0) surfaces induced by impact of Al ions and Al N clusters ( N=2,4,6,9,13,55) with energies of 100 and 500 eV/atom is studied at atomic scale by means of classical molecular dynamics (MD). The MD code we used implements many-body tight binding potential splined to ZBL at short distances. Special attention has been paid to model dense cascades: we used quite big computation cells with lateral periodic and damped boundary conditions. In addition, long simulation times (10-25 ps) and representative statistics (up to 1000 runs per each case) were considered. The total sputtering yields, energy and time spectrums of sputtered particles, as well as preferential sputtering of compound target were analyzed, both in the linear and non-linear regimes. The significant "cluster enhancement" of sputtering yield was found for cluster sizes N⩾13. In parallel, we estimated collision cascade features depending on cluster size in order to interpret the nature of observed non-linear effects.
Pump and probe spectroscopy with continuous wave quantum cascade lasers.
Kirkbride, James M R; Causier, Sarah K; Dalton, Andrew R; Weidmann, Damien; Ritchie, Grant A D
2014-02-07
This paper details infra-red pump and probe studies on nitric oxide conducted with two continuous wave quantum cascade lasers both operating around 5 μm. The pump laser prepares a velocity selected population in a chosen rotational quantum state of the v = 1 level which is subsequently probed using a second laser tuned to a rotational transition within the v = 2 ← v = 1 hot band. The rapid frequency scan of the probe (with respect to the molecular collision rate) in combination with the velocity selective pumping allows observation of marked rapid passage signatures in the transient absorption profiles from the polarized vibrationally excited sample. These coherent transient signals are influenced by the underlying hyperfine structure of the pump and probe transitions, the sample pressure, and the coherent properties of the lasers. Pulsed pump and probe studies show that the transient absorption signals decay within 1 μs at 50 mTorr total pressure, reflecting both the polarization and population dephasing times of the vibrationally excited sample. The experimental observations are supported by simulation based upon solving the optical Bloch equations for a two level system.
NASA Astrophysics Data System (ADS)
Springer, H.; Miller, W.; Levatin, J.; Pertica, A.; Olivier, S.
2010-09-01
Satellite collision debris poses risks to existing space assets and future space missions. Predictive models of debris generated from these hypervelocity collisions are critical for developing accurate space situational awareness tools and effective mitigation strategies. Hypervelocity collisions involve complex phenomenon that spans several time and length-scales. We have developed a satellite collision debris modeling approach consisting of a Lagrangian hydrocode enriched with smooth particle hydrodynamics (SPH), advanced material failure models, detailed satellite mesh models, and massively parallel computers. These computational studies enable us to investigate the influence of satellite center-of-mass (CM) overlap and orientation, relative velocity, and material composition on the size, velocity, and material type distributions of collision debris. We have applied our debris modeling capability to the recent Iridium 33-Cosmos 2251 collision event. While the relative velocity was well understood in this event, the degree of satellite CM overlap and orientation was ill-defined. In our simulations, we varied the collision CM overlap and orientation of the satellites from nearly maximum overlap to partial overlap on the outermost extents of the satellites (i.e, solar panels and gravity boom). As expected, we found that with increased satellite overlap, the overall debris cloud mass and momentum (transfer) increases, the average debris size decreases, and the debris velocity increases. The largest predicted debris can also provide insight into which satellite components were further removed from the impact location. A significant fraction of the momentum transfer is imparted to the smallest debris (< 1-5mm, dependent on mesh resolution), especially in large CM overlap simulations. While the inclusion of the smallest debris is critical to enforcing mass and momentum conservation in hydrocode simulations, there seems to be relatively little interest in their disposition. Based on comparing our results to observations, it is unlikely that the Iridium 33-Cosmos 2251 collision event was a large mass-overlap collision. We also performed separate simulations studying the debris generated by the collision of 5 and 10 cm spherical projectiles on the Iridium 33 satellite at closing velocities of 5, 10, and 15 km/s. It is important to understand the vulnerability of satellites to small debris threats, given their pervasiveness in orbit. These studies can also be merged with probabilistic conjunction analysis to better understand the risk to space assets. In these computational studies, we found that momentum transfer, kinetic energy losses due to dissipative mechanisms (e.g., fracture), fragment number, and fragment velocity increases with increasing velocity for a fixed projectile size. For a fixed velocity, we found that the smaller projectile size more efficiently transfers momentum to the satellite. This latter point has an important implication: Eight (spaced) 5 cm debris objects can impart more momentum to the satellite, and likely cause more damage, than a single 10 cm debris object at the same velocity. Further studies are required to assess the satellite damage induced by 1-5 cm sized debris objects, as well as multiple debris objects, in this velocity range.
Side Object Detection Systems Evaluation : Final Evaluation Report.
DOT National Transportation Integrated Search
2008-12-15
Nearly 46 percent of bus accidents across the United States each year occur on the left or right side of the bus. These collisions result in property damage, and they can negatively impact on revenue operations and public perception. The first commer...
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bradley, R. Mark
2016-04-07
We modify the theory of nanoscale patterns produced by ion bombardment with concurrent impurity deposition to take into account the effect that the near-surface impurities have on the collision cascades. As the impurity concentration is increased, the resulting theory successively yields a flat surface, a rippled surface with its wavevector along the projected direction of ion incidence, and a rippled surface with its wavevector rotated by 90°. Exactly the same morphological transitions were observed in recent experiments in which silicon was bombarded with an argon ion beam and gold was co-deposited [Moon et al., e-print arXiv:1601.02534].
Neutron displacement cross-sections for tantalum and tungsten at energies up to 1 GeV
NASA Astrophysics Data System (ADS)
Broeders, C. H. M.; Konobeyev, A. Yu.; Villagrasa, C.
2005-06-01
The neutron displacement cross-section has been evaluated for tantalum and tungsten at energies from 10 -5 eV up to 1 GeV. The nuclear optical model, the intranuclear cascade model combined with the pre-equilibrium and evaporation models were used for the calculations. The number of defects produced by recoil atoms nuclei in materials was calculated by the Norgett, Robinson, Torrens model and by the approach combining calculations using the binary collision approximation model and the results of the molecular dynamics simulation. The numerical calculations were done using the NJOY code, the ECIS96 code, the MCNPX code and the IOTA code.
2014-03-27
Source The laser probe in use for this test is a Daylight Solutions Unicorn II quantum cascade laser operating at 3.77 µm. According to the laser...San Diego, CA, Spec Sheet: Unicorn II Fixed-Wavelength Mid-IR External Cavity Lasers. 51 REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704–0188 The
Gregory M. Filip; Alan Kanaskie; Will R. Littke; John Browning; Kristen L. Chadwick; David C. Shaw; Robin L. Mulvey
2014-01-01
Swiss needle cast (SNC), caused by the fungus Phaeocryptopus gaeumannii, is one of the most damaging diseases of coast Douglasfir (Pseudotsuga menziesii var. menziesii) in the Pacific Northwest (Hansen and others 2000, Mainwaring and others 2005, Shaw and others 2011).
NASA Astrophysics Data System (ADS)
Chen, Jiamin; Luo, Xiaofeng; Liu, Feng; Nara, Yasushi
2018-01-01
We perform a systematic study of elliptic flow (v 2) in Au+Au collisions at \\sqrt{{s}NN}}=5 {GeV} by using a microscopic transport model, JAM. The centrality, pseudorapidity, transverse momentum and beam energy dependence of v 2 for charged as well as identified hadrons are studied. We investigate the effects of both the hadronic mean-field and the softening of equation of state (EoS) on elliptic flow. The softening of the EoS is realized by imposing attractive orbits in two body scattering, which can reduce the pressure of the system. We found that the softening of the EoS leads to the enhancement of v 2, while the hadronic mean-field suppresses v 2 relative to the cascade mode. It indicates that elliptic flow at high baryon density regions is highly sensitive to the EoS and the enhancement of v 2 may probe the signature of a first-order phase transition in heavy-ion collisions at beam energies of a strong baryon stopping region. Supported by the MoST of China 973-Project (2015CB856901), NSFC (11575069, 11221504). Y. N. is supported by the Grants-in-Aid for Scientific Research from JSPS (15K05079, 15K05098)
Butterworth, A; Ferrari, A; Tsoulou, E; Vlachoudis, V; Wijnands, T
2005-01-01
Monte Carlo simulations have been performed to estimate the radiation damage induced by high-energy hadrons in the digital electronics of the RF low-level systems in the LHC cavities. High-energy hadrons are generated when the proton beams interact with the residual gas. The contributions from various elements-vacuum chambers, cryogenic cavities, wideband pickups and cryomodule beam tubes-have been considered individually, with each contribution depending on the gas composition and density. The probability of displacement damage and single event effects (mainly single event upsets) is derived for the LHC start-up conditions.
Radiation damage buildup by athermal defect reactions in nickel and concentrated nickel alloys
Zhang, S.; Nordlund, K.; Djurabekova, F.; ...
2017-04-12
We develop a new method using binary collision approximation simulating the Rutherford backscattering spectrometry in channeling conditions (RBS/C) from molecular dynamics atom coordinates of irradiated cells. The approach allows comparing experimental and simulated RBS/C signals as a function of depth without fitting parameters. The simulated RBS/C spectra of irradiated Ni and concentrated solid solution alloys (CSAs, NiFe and NiCoCr) show a good agreement with the experimental results. The good agreement indicates the damage evolution under damage overlap conditions in Ni and CSAs at room temperature is dominated by defect recombination and migration induced by irradiation rather than activated thermally.
DOT National Transportation Integrated Search
2005-01-01
The rapid increase in animal-vehicle collisions on U.S. roadways is a growing concern in terms of human safety, property damage and injury costs, and viability of wildlife populations. Wildlife crossing structures are gaining national recognition by ...
Repair of impact damaged utility poles with fiber reinforced polymers (FRP), phase II : [summary].
DOT National Transportation Integrated Search
2015-04-01
The aluminum and steel utility poles which support traffic signals, lighting, or mast-arm signs : are vulnerable to collisions from vehicles because of proximity to roadways. Removing these : poles for repair is costly and time-consuming, and removal...
DOT National Transportation Integrated Search
2012-02-01
The permanent deformations in steel beam bridges caused by collision with high profile vehicles can be repaired by heat straightening, : which is a structurally efficient and costeffective repair process developed by many engineers over the years....
Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie; Xi, Zhide
2018-01-01
In order to access the fretting damage of the steam generator tube (SGT), a fast fiber Fabry-Perot (F-P) non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED) was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP) was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail. Specially, a piezoelectric ceramic transducer (PZT) modulation method was developed to get rid of the interference of mode coupling induced by different types of fiber optics in the demodulation system. The reflectivity of optical wedge and F-P sensor was optimized. Finally, the demodulation system worked well in a 1:1 steam generator test loop and successfully demodulated a force signal of 32 N with a collision time of 2 ms. PMID:29329225
Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie; Xi, Zhide
2018-01-12
In order to access the fretting damage of the steam generator tube (SGT), a fast fiber Fabry-Perot (F-P) non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED) was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP) was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail. Specially, a piezoelectric ceramic transducer (PZT) modulation method was developed to get rid of the interference of mode coupling induced by different types of fiber optics in the demodulation system. The reflectivity of optical wedge and F-P sensor was optimized. Finally, the demodulation system worked well in a 1:1 steam generator test loop and successfully demodulated a force signal of 32 N with a collision time of 2 ms.
Using GPS telemetry to determine roadways most susceptible to deer-vehicle collisions
Kramer, David W.; Prebyl, Thomas J.; Stickles, James H.; Osborn, David A.; Irwin, Brian J.; Nibbelink, Nathan P.; Warren, Robert J.; Miller, Karl V.
2016-01-01
More than 1 million wildlife-vehicle collisions occur annually in the United States. The majority of these accidents involve white-tailed deer (Odocoileus virginianus) and result in >US $4.6 billion in damage and >200 human fatalities. Prior research has used collision locations to assess sitespecific as well as landscape features that contribute to risk of deer-vehicle collisions. As an alternative approach, we calculated road-crossing locations from 25 GPS-instrumented white-tailed deer near Madison, Georgia (n=154,131 hourly locations). We identified crossing locations by creating movement paths between subsequent GPS points and then intersecting the paths with road locations. Using AIC model selection, we determined whether 10 local and landscape variables were successful at identifying areas where higher frequencies of deer crossings were likely to occur. Our findings indicate that traffic volume, distance to riparian areas, and the amount of forested area influenced the frequency of road crossings. Roadways that were predominately located in wooded landscapes and 200–300 m from riparian areas were crossed frequently. Additionally, we found that areas of low traffic volume (e.g., county roads) had the highest frequencies of deer crossings. Analyses utilizing only records of deer-vehicle collision locations cannot separate the relative contribution of deer crossing rates and traffic volume. Increased frequency of road crossings by deer in low-traffic, forested areas may lead to a greater risk of deer-vehicle collision than suggested by evaluations of deer-vehicle collision frequency alone.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Springer, H K; Miller, W O; Levatin, J L
Satellite collision debris poses risks to existing space assets and future space missions. Predictive models of debris generated from these hypervelocity collisions are critical for developing accurate space situational awareness tools and effective mitigation strategies. Hypervelocity collisions involve complex phenomenon that spans several time- and length-scales. We have developed a satellite collision debris modeling approach consisting of a Lagrangian hydrocode enriched with smooth particle hydrodynamics (SPH), advanced material failure models, detailed satellite mesh models, and massively parallel computers. These computational studies enable us to investigate the influence of satellite center-of-mass (CM) overlap and orientation, relative velocity, and material composition onmore » the size, velocity, and material type distributions of collision debris. We have applied our debris modeling capability to the recent Iridium 33-Cosmos 2251 collision event. While the relative velocity was well understood in this event, the degree of satellite CM overlap and orientation was ill-defined. In our simulations, we varied the collision CM overlap and orientation of the satellites from nearly maximum overlap to partial overlap on the outermost extents of the satellites (i.e, solar panels and gravity boom). As expected, we found that with increased satellite overlap, the overall debris cloud mass and momentum (transfer) increases, the average debris size decreases, and the debris velocity increases. The largest predicted debris can also provide insight into which satellite components were further removed from the impact location. A significant fraction of the momentum transfer is imparted to the smallest debris (< 1-5mm, dependent on mesh resolution), especially in large CM overlap simulations. While the inclusion of the smallest debris is critical to enforcing mass and momentum conservation in hydrocode simulations, there seems to be relatively little interest in their disposition. Based on comparing our results to observations, it is unlikely that the Iridium 33-Cosmos 2251 collision event was a large mass-overlap collision. We also performed separate simulations studying the debris generated by the collision of 5 and 10 cm spherical projectiles on the Iridium 33 satellite at closing velocities of 5, 10, and 15 km/s. It is important to understand the vulnerability of satellites to small debris threats, given their pervasiveness in orbit. These studies can also be merged with probabilistic conjunction analysis to better understand the risk to space assets. In these computational studies, we found that momentum transfer, kinetic energy losses due to dissipative mechanisms (e.g., fracture), fragment number, and fragment velocity increases with increasing velocity for a fixed projectile size. For a fixed velocity, we found that the smaller projectile size more efficiently transfers momentum to the satellite. This latter point has an important implication: Eight (spaced) 5 cm debris objects can impart more momentum to the satellite, and likely cause more damage, than a single 10 cm debris object at the same velocity. Further studies are required to assess the satellite damage induced by 1-5 cm sized debris objects, as well as multiple debris objects, in this velocity range.« less
Chen, Han-Sen; Chen, Xi; Li, Wen-Ting; Shen, Jian-Gang
2018-05-01
Reactive nitrogen species (RNS) play important roles in mediating cerebral ischemia-reperfusion injury. RNS activate multiple signaling pathways and participate in different cellular events in cerebral ischemia-reperfusion injury. Recent studies have indicated that caveolin-1 and matrix metalloproteinase (MMP) are important signaling molecules in the pathological process of ischemic brain injury. During cerebral ischemia-reperfusion, the production of nitric oxide (NO) and peroxynitrite (ONOO - ), two representative RNS, down-regulates the expression of caveolin-1 (Cav-1) and, in turn, further activates nitric oxide synthase (NOS) to promote RNS generation. The increased RNS further induce MMP activation and mediate disruption of the blood-brain barrier (BBB), aggravating the brain damage in cerebral ischemia-reperfusion injury. Therefore, the feedback interaction among RNS/Cav-1/MMPs provides an amplified mechanism for aggravating ischemic brain damage during cerebral ischemia-reperfusion injury. Targeting the RNS/Cav-1/MMP pathway could be a promising therapeutic strategy for protecting against cerebral ischemia-reperfusion injury. In this mini-review article, we highlight the important role of the RNS/Cav-1/MMP signaling cascades in ischemic stroke injury and review the current progress of studies seeking therapeutic compounds targeting the RNS/Cav-1/MMP signaling cascades to attenuate cerebral ischemia-reperfusion injury. Several representative natural compounds, including calycosin-7-O-β-D-glucoside, baicalin, Momordica charantia polysaccharide (MCP), chlorogenic acid, lutein and lycopene, have shown potential for targeting the RNS/Cav-1/MMP signaling pathway to protect the brain in ischemic stroke. Therefore, the RNS/Cav-1/MMP pathway is an important therapeutic target in ischemic stroke treatment.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sirunyan, A. M.; Tumasyan, A.; Adam, W.
Results are reported from a search for new physics in 13 TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H→more » $$b\\bar{b}$$. The search uses a data sample accumulated by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb -1. The search is motivated by models based on gauge-mediated supersymmetry breaking, which predict the electroweak production of a pair of Higgsinos, each of which can decay via a cascade process to a Higgs boson and an undetected lightest supersymmetric particle. The observed event yields in the signal regions are consistent with the standard model background expectation obtained from control regions in data. Higgsinos in the mass range 230–770 GeV are excluded at 95% confidence level in the context of a simplified model for the production and decay of approximately degenerate Higgsinos.« less
NASA Astrophysics Data System (ADS)
Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Grossmann, J.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; Pree, E.; Rabady, D.; Rad, N.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Spanring, M.; Spitzbart, D.; Strauss, J.; Waltenberger, W.; Wittmann, J.; Wulz, C.-E.; Zarucki, M.; Chekhovsky, V.; Mossolov, V.; Suarez Gonzalez, J.; De Wolf, E. A.; Di Croce, D.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; De Bruyn, I.; De Clercq, J.; Deroover, K.; Flouris, G.; Lontkovskyi, D.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Roskas, C.; Salva, S.; Tytgat, M.; Verbeke, W.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Melo De Almeida, M.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Misheva, M.; Rodozov, M.; Shopova, M.; Stoykova, S.; Sultanov, G.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Gao, X.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Jiang, C. H.; Leggat, D.; Liao, H.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Yazgan, E.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Courbon, B.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Starodumov, A.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Assran, Y.; Mahmoud, M. A.; Mahrous, A.; Dewanjee, R. K.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Faure, J. L.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Negro, G.; Rander, J.; Rosowsky, A.; Sahin, M. Ö.; Titov, M.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Charlot, C.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Lobanov, A.; Martin Blanco, J.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Jansová, M.; Le Bihan, A.-C.; Tonon, N.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Finco, L.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Viret, S.; Khvedelidze, A.; Bagaturia, I.; Autermann, C.; Beranek, S.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Verlage, T.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Teyssier, D.; Thüer, S.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bermúdez Martínez, A.; Bin Anuar, A. A.; Borras, K.; Botta, V.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Lipka, K.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Savitskyi, M.; Saxena, P.; Shevchenko, R.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wen, Y.; Wichmann, K.; Wissing, C.; Zenaiev, O.; Bein, S.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hinzmann, A.; Hoffmann, M.; Karavdina, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Kurz, S.; Lapsien, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sonneveld, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baur, S.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Freund, B.; Friese, R.; Giffels, M.; Gilbert, A.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Kassel, F.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Evangelou, I.; Foudas, C.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Strologas, J.; Triantis, F. A.; Csanad, M.; Filipovic, N.; Pasztor, G.; Bencze, G.; Hajdu, C.; Horvath, D.; Hunyadi, Á.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. 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I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Pazzini, J.; Piperov, S.; Sagir, S.; Syarif, R.; Yu, D.; Band, R.; Brainerd, C.; Burns, D.; Calderon De La Barca Sanchez, M.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Squires, M.; Stolp, D.; Tos, K.; Tripathi, M.; Wang, Z.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wang, L.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cittolin, S.; Derdzinski, M.; Hashemi, B.; Holzner, A.; Klein, D.; Kole, G.; Krutelyov, V.; Letts, J.; Macneill, I.; Masciovecchio, M.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mullin, S. D.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bendavid, J.; Bornheim, A.; Lawhorn, J. M.; Newman, H. B.; Nguyen, T.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhang, Z.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Mudholkar, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Abdullin, S.; Albrow, M.; Apollinari, G.; Apresyan, A.; Apyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cerati, G. B.; Cheung, H. W. K.; Chlebana, F.; Cremonesi, M.; Duarte, J.; Elvira, V. D.; Freeman, J.; Gecse, Z.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Schneider, B.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Kotov, K.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Sperka, D.; Terentyev, N.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Joshi, Y. R.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Perry, T.; Prosper, H.; Saha, A.; Santra, A.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Tonjes, M. B.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Royon, C.; Sanders, S.; Schmitz, E.; Stringer, R.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Loukas, N.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Benaglia, A.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Higginbotham, S.; Lange, D.; Luo, J.; Marlow, D.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Malik, S.; Norberg, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Peng, C. C.; Schulte, J. F.; Sun, J.; Wang, F.; Xie, W.; Cheng, T.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Ciesielski, R.; Goulianos, K.; Mesropian, C.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.; CMS Collaboration
2018-02-01
Results are reported from a search for new physics in 13 TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H →b b ¯ . The search uses a data sample accumulated by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb-1 . The search is motivated by models based on gauge-mediated supersymmetry breaking, which predict the electroweak production of a pair of Higgsinos, each of which can decay via a cascade process to a Higgs boson and an undetected lightest supersymmetric particle. The observed event yields in the signal regions are consistent with the standard model background expectation obtained from control regions in data. Higgsinos in the mass range 230-770 GeV are excluded at 95% confidence level in the context of a simplified model for the production and decay of approximately degenerate Higgsinos.
Search for a Two-Higgs-Boson Doublet Using a Simplified Model in pp̄ Collisions at √s=1.96 TeV
Aaltonen, T.; Adelman, J.; Álvarez González, B.; ...
2013-03-18
We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson (H⁰), a lighter charged Higgs boson (H ±), and an even lighter Higgs boson h⁰, with decays leading to a W-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, and at least four jets in data corresponding to an integrated luminosity of 8.7 fb⁻¹ collected by the CDF II detector in proton-antiproton collisions at √s=1.96 TeV. We find the data to be consistent with standard model predictions andmore » report the results in terms of a simplified Higgs-cascade-decay model, setting 95% confidence level upper limits on the product of cross section and branching fraction from 1.3 pb to 15 fb as a function of H⁰ and H ± masses for m⁰ h=126 GeV/c²« less
NASA Astrophysics Data System (ADS)
Mohammadi, Naghmeh;
2017-01-01
The latest ALICE results on the centrality and transverse momentum dependence of v 2, v 3, v 4 and v 5 for π± , K ± and p() in Pb-Pb collisions at = 2.76 TeV are presented. The flow coefficients exhibit a clear mass ordering for p T < 2.5 GeV/c for all harmonics. For transverse momentum values larger than about 3 GeV/c, mesons exhibit distinctively lower flow values compared to baryons, suggesting that coalescence might be the relevant particle production mechanism in this region. The experimental data for p T < 2.5 GeV/c are described fairly well by the hydrodynamical model iEBE-VISHNU, which models the hydrodynamical expansion of the fireball using a value of η/s = 0.08, coupled to a hadronic cascade model (UrQMD). Finally, A Multi-Phase Transition Model (AMPT) highlights the significant contribution of the hadronic rescattering phase and of coalescence as the dominant particle production mechanism to the mass ordering at low p T and the baryon-meson grouping at intermediate p T, respectively.
Aaltonen, T; Adelman, J; Álvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bisello, D; Bizjak, I; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Calamba, A; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chung, W H; Chung, Y S; Ciocci, M A; Clark, A; Clarke, C; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; Dell'Orso, M; Demortier, L; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, M; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, S; Ershaidat, N; Eusebi, R; Farrington, S; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Funakoshi, Y; Furic, I; Gallinaro, M; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Johnstone, A; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kim, Y J; Kimura, N; Kirby, M; Klimenko, S; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lin, C-J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Mastrandrea, P; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Prokoshin, F; Pranko, A; Ptohos, F; Punzi, G; Rahaman, A; Ramakrishnan, V; Ranjan, N; Rao, K; Redondo, I; Renton, P; Rescigno, M; Riddick, T; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sinervo, P; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Sorin, V; Song, H; Squillacioti, P; Stancari, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Truong, A; Ukegawa, F; Uozumi, S; Varganov, A; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zhou, C; Zucchelli, S
2013-03-22
We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson (H(0)), a lighter charged Higgs boson (H(±)), and an even lighter Higgs boson h(0), with decays leading to a W-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, and at least four jets in data corresponding to an integrated luminosity of 8.7 fb(-1) collected by the CDF II detector in proton-antiproton collisions at sqrt[s]= 1.96 TeV. We find the data to be consistent with standard model predictions and report the results in terms of a simplified Higgs-cascade-decay model, setting 95% confidence level upper limits on the product of cross section and branching fraction from 1.3 pb to 15 fb as a function of H(0) and H(±) masses for m(h)(0) = 126 GeV/c(2).
El-Atwani, O.; Norris, S. A.; Ludwig, K.; ...
2015-12-16
In this study, several proposed mechanisms and theoretical models exist concerning nanostructure evolution on III-V semiconductors (particularly GaSb) via ion beam irradiation. However, making quantitative contact between experiment on the one hand and model-parameter dependent predictions from different theories on the other is usually difficult. In this study, we take a different approach and provide an experimental investigation with a range of targets (GaSb, GaAs, GaP) and ion species (Ne, Ar, Kr, Xe) to determine new parametric trends regarding nanostructure evolution. Concurrently, atomistic simulations using binary collision approximation over the same ion/target combinations were performed to determine parametric trends onmore » several quantities related to existing model. A comparison of experimental and numerical trends reveals that the two are broadly consistent under the assumption that instabilities are driven by chemical instability based on phase separation. Furthermore, the atomistic simulations and a survey of material thermodynamic properties suggest that a plausible microscopic mechanism for this process is an ion-enhanced mobility associated with energy deposition by collision cascades.« less
Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...
2018-02-08
Results are reported from a search for new physics in 13 TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H→more » $$b\\bar{b}$$. The search uses a data sample accumulated by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb -1. The search is motivated by models based on gauge-mediated supersymmetry breaking, which predict the electroweak production of a pair of Higgsinos, each of which can decay via a cascade process to a Higgs boson and an undetected lightest supersymmetric particle. The observed event yields in the signal regions are consistent with the standard model background expectation obtained from control regions in data. Higgsinos in the mass range 230–770 GeV are excluded at 95% confidence level in the context of a simplified model for the production and decay of approximately degenerate Higgsinos.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.
We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascademore » production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.« less
Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.
2015-06-03
We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascademore » production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.« less
The role of the baryon junction in relativistic heavy-ion collisions
NASA Astrophysics Data System (ADS)
Vance, Stephen Earl
The non-perturbative nature of the conserved baryon number of nuclei is investigated by studying the role of the baryon junction in relativistic heavy-ion collisions. The junction, J, of a baryon originates in the Standard Model of Strong Interactions (QCD) and is the vertex which connects the color flux (Wilson) lines flowing from the three valence quarks. In high energy interactions, the baryon junction can play a dynamical role through the Regge exchange of junction states. We show that the junction exchange provides a natural mechanism for the transport of baryon number into the central rapidity region and has the remarkable ability to produce valence hyperons, including W- baryons. This mechanism is used to describe the observed baryon stopping and associated hyperon production in nucleus-nucleus collisions at the CERN SPS. We also show that junction - antijunction excitations or JJ loops provide a new mechanism for baryon pair production and lead to enhanced hyperon and antihyperon production. The combination of these two mechanisms is able to explain part of the anomalous hyperon production observed in Pb + Pb collisions at the SPS. Using the junction initial state dynamics, final state strangeness exchange interactions are shown to further enhance hyperon production and are proposed as an explanation of the remaining anomalous hyperon production. With larger phase space (higher energy) accessible at the newly constructed BNL RHIC facility, we propose that the observation of valence W- baryons in pp collisions will be a decisive observable to confirm the junction exchange picture of baryon number transport. In addition, we note that novel rapidity correlations between baryons and antibaryons of completely different quark flavors, like D++(uuu) and W+( ss s) , are predicted by the JJ loop mechanism. For numerical calculations of multiparticle observables associated with these junction mechanisms, we developed the HIJING/BB¯ nuclear event generator. HIJING/BB¯ was then coupled to the General Cascade Program (GCP) to study the role of the final state flavor changing interactions.
Luo, Man; Bao, Zhengqiang; Xu, Feng; Wang, Xiaohui; Li, Fei; Li, Wen; Chen, Zhihua; Ying, Songmin; Shen, Huahao
2018-04-14
The inflammatory cascade can be initiated with the recognition of damaged DNA. Macrophages play an essential role in particulate matter (PM)-induced airway inflammation. In this study, we aim to explore the PM induced DNA damage response of macrophages and its function in airway inflammation. The DNA damage response and inflammatory response were assessed using bone marrow-derived macrophages following PM treatment and mouse model instilled intratracheally with PM. We found that PM induced significant DNA damage both in vitro and in vivo and simultaneously triggered a rapid DNA damage response, represented by nuclear RPA, 53BP1 and γH2AX foci formation. Genetic ablation or chemical inhibition of the DNA damage response sensor amplified the production of cytokines including Cxcl1, Cxcl2 and Ifn-γ after PM stimulation in bone marrow-derived macrophages. Similar to that seen in vitro , mice with myeloid-specific deletion of RAD50 showed higher levels of airway inflammation in response to the PM challenge, suggesting a protective role of DNA damage sensor during inflammation. These data demonstrate that PM exposure induces DNA damage and activation of DNA damage response sensor MRN complex in macrophages. Disruption of MRN complex lead to persistent, unrepaired DNA damage that causes elevated inflammatory response.
Systemic Prenatal Insults Disrupt Telencephalon Development
Robinson, Shenandoah
2006-01-01
Infants born prematurely are prone to chronic neurologic deficits including cerebral palsy (CP), epilepsy, cognitive delay, behavioral problems, and neurosensory impairments. In affected children, imaging and neuropathological findings demonstrate significant damage to white matter. The extent of cortical damage has been less obvious. Advances in the understanding of telencephalon development provide insights into how systemic intrauterine insults affect the developing white matter, subplate and cortex, and lead to multiple neurologic impairments. In addition to white matter oligodendrocytes and axons, other elements at risk for perinatal brain injury include subplate neurons, GABAergic neurons migrating through white matter and subplate, and afferents of maturing neurotransmitter systems. Common insults including hypoxia-ischemia and infection often affect the developing brain differently than the mature brain, and insults precipitate a cascade of damage to multiple neural lineages. Insights from development can identify potential targets for therapies to repair the damaged neonatal brain before it has matured. PMID:16061421
Analysis of neutron spectrum effects on primary damage in tritium breeding blankets
NASA Astrophysics Data System (ADS)
Choi, Yong Hee; Joo, Han Gyu
2012-07-01
The effect of neutron spectrum on primary damages in a structural material of a tritium breeding blanket is investigated with a newly established recoil spectrum estimation system. First, a recoil spectrum generation code is developed to obtain the energy spectrum of primary knock-on atoms (PKAs) for a given neutron spectrum utilizing the latest ENDF/B data. Secondly, a method for approximating the high energy tail of the recoil spectrum is introduced to avoid expensive molecular dynamics calculations for high energy PKAs using the concept of recoil energy of the secondary knock-on atoms originated by the INtegration of CAScades (INCAS) model. Thirdly, the modified spectrum is combined with a set of molecular dynamics calculation results to estimate the primary damage parameters such as the number of surviving point defects. Finally, the neutron spectrum is varied by changing the material of the spectral shifter and the result in primary damage parameters is examined.
Design and construction of a full-scale lateral impact testing facility.
DOT National Transportation Integrated Search
2015-05-01
The goal of this work is to design and construct a full scale lateral impact testing facility that is capable of recreating the damage that would be created by an overheight vehicle collision. This was accomplished by impacting a test specimen with 8...
Atomistic simulation of damage accumulation and amorphization in Ge
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gomez-Selles, Jose L., E-mail: joseluis.gomezselles@imdea.org; Martin-Bragado, Ignacio; Claverie, Alain
2015-02-07
Damage accumulation and amorphization mechanisms by means of ion implantation in Ge are studied using Kinetic Monte Carlo and Binary Collision Approximation techniques. Such mechanisms are investigated through different stages of damage accumulation taking place in the implantation process: from point defect generation and cluster formation up to full amorphization of Ge layers. We propose a damage concentration amorphization threshold for Ge of ∼1.3 × 10{sup 22} cm{sup −3} which is independent on the implantation conditions. Recombination energy barriers depending on amorphous pocket sizes are provided. This leads to an explanation of the reported distinct behavior of the damage generated by different ions.more » We have also observed that the dissolution of clusters plays an important role for relatively high temperatures and fluences. The model is able to explain and predict different damage generation regimes, amount of generated damage, and extension of amorphous layers in Ge for different ions and implantation conditions.« less
Transcription and DNA Damage: Holding Hands or Crossing Swords?
D'Alessandro, Giuseppina; d'Adda di Fagagna, Fabrizio
2017-10-27
Transcription has classically been considered a potential threat to genome integrity. Collision between transcription and DNA replication machinery, and retention of DNA:RNA hybrids, may result in genome instability. On the other hand, it has been proposed that active genes repair faster and preferentially via homologous recombination. Moreover, while canonical transcription is inhibited in the proximity of DNA double-strand breaks, a growing body of evidence supports active non-canonical transcription at DNA damage sites. Small non-coding RNAs accumulate at DNA double-strand break sites in mammals and other organisms, and are involved in DNA damage signaling and repair. Furthermore, RNA binding proteins are recruited to DNA damage sites and participate in the DNA damage response. Here, we discuss the impact of transcription on genome stability, the role of RNA binding proteins at DNA damage sites, and the function of small non-coding RNAs generated upon damage in the signaling and repair of DNA lesions. Copyright © 2016 Elsevier Ltd. All rights reserved.
Charge Exchange of Highly Charged Ne and Mg Ions with H and He
NASA Astrophysics Data System (ADS)
Lyons, D.; Cumbee, R. S.; Stancil, P. C.
2017-10-01
Cross sections for single electron capture (SEC), or charge exchange (CX), in collisions of Ne(8-10)+ and Mg(8-12)+ with H and He, are computed using an approximate multichannel Landau-Zener (MCLZ) formalism. Final-state-resolved cross sections for the principal (n), orbital angular momentum (ℓ), and where appropriate, total spin angular momentum (S) quantum numbers are explicitly computed, except for the incident bare ions Ne10+ and Mg12+. In the latter two cases, n{\\ell }-resolution is obtained from analytical ℓ-distribution functions applied to n-resolved MCLZ cross sections. In all cases, the cross sections are computed over the collision energy range 1 meV/u to 50 keV/u with LZ parameters estimated from atomic energies obtained from experiment, theory, or, in the case of high-lying Rydberg levels, estimated with a quantum defect approach. Errors in the energy differences in the adiabatic potentials at the avoided crossing distances give the largest contribution to the uncertainties in the cross sections, which are expected to increase with decreasing cross section magnitude. The energy differences are deduced here with the Olson-Salop-Tauljberg radial coupling model. Proper selection of an ℓ-distribution function for bare ion collisions introduces another level of uncertainty into the results. Comparison is made to existing experimental or theoretical results when available, but such data are absent for most considered collision systems. The n{\\ell }S-resolved SEC cross sections are used in an optically thin cascade simulation to predict X-ray spectra and line ratios that will aid in modeling the X-ray emission in environments where CX is an important mechanism. Details on a MCLZ computational package, Stueckelberg, are also provided.
NASA Astrophysics Data System (ADS)
Sahi, Qurat-ul-ain; Kim, Yong-Soo
2018-05-01
Knowledge of defects generation, their mobility, growth rate, and spatial distribution is the cornerstone for understanding the surface and structural evolution of a material used under irradiation conditions. In this study, molecular dynamics simulations were used to investigate the coupled effect of primary knock-on atom (PKA) energy and applied strain (uniaxial and hydrostatic) fields on primary radiation damage evolution in pure aluminum. Cascade damage simulations were carried out for PKA energy ranging between 1 and 20 keV and for applied strain values ranging between -2% and 2% at the fixed temperature of 300 K. Simulation results showed that as the atomic displacement cascade proceeds under uniaxial and hydrostatic strains, the peak and surviving number of Frenkel point defects increases with increasing tension; however, these increments were more prominent under larger volume changing deformations (hydrostatic strain). The percentage fraction of point defects that aggregate into clusters increases under tension conditions; compared to the reference conditions with no strain, these increases are around 13% and 7% for interstitials and vacancies, respectively (under 2% uniaxial strain), and 19% and 11% for interstitials and vacancies, respectively (under 2% hydrostatic strain). Clusters formed of vacancies and interstitials were both larger under tensile strain conditions, with increases in both the average and maximum cluster sizes. The rate of increase/decrease in the number of Frenkel pairs, their clustering, and their size distributions under expansion/compression strain conditions were higher for higher PKA energies. Overall, the present results suggest that strain effects should be considered carefully in radiation damage environments, specifically for conditions of low temperature and high radiation energy. Compressive strain conditions could be beneficial for materials used in nuclear reactor power systems.
Saha, Sukanya; Sadhukhan, Pritam; Sinha, Krishnendu; Agarwal, Namrata; Sil, Parames C
2016-03-01
Mangiferin is a polyphenolic xanthonoid with remarkable antioxidant activity. Oxidative stress plays the key role in tert-butyl hydroperoxide (tBHP) induced renal cell damage. In this scenario, we consider mangiferin, as a safe agent in tBHP induced renal cell death and rationalize its action systematically, in normal human kidney epithelial cells (NKE). NKE cells were exposed to 20 µM mangiferin for 2 h followed by 50 µM tBHP for 18 h. The effect on endogenous ROS production, antioxidant status (antioxidant enzymes and thiols), mitochondrial membrane potential, apoptotic signaling molecules, PI3K mediated signaling cascades and cell cycle progression were examined using various biochemical assays, FACS and immunoblot analyses. tBHP exposure damaged the NKE cells and decreased its viability. It also elevated the intracellular ROS and other oxidative stress-related biomarkers within the cells. However, mangiferin dose dependently, exhibited significant protection against this oxidative cellular damage. Mangiferin inhibited tBHP induced activation of different pro-apoptotic signals and thus protected the renal cells against mitochondrial permeabilization. Further, mangiferin enhanced the expression of cell proliferative signaling cascade molecules, Cyclin d1, NFκB and antioxidant molecules HO-1, SOD2, by PI3K/Akt dependent pathway. However, the inhibitor of PI3K abolished mangiferin's protective activity. Results show Mangiferin maintains the intracellular anti-oxidant status, induces the expression of PI3K and its downstream molecules and shields NKE cells against the tBHP induced cytotoxicity. Mangiferin can be indicated as a therapeutic agent in oxidative stress-mediated renal toxicity. This protective action of mangiferin primarily attributes to its potent antioxidant and antiapoptotic nature.
Early lessons from commercial thinning in a 30-year-old Sitka Spruce-Western Hemlock forest.
Sarah E. Greene; William H. Emmingham
1986-01-01
A commercial thinning study was undertaken in a 30-year-old stand, pre-commercially thinned at 15 years of age, at Cascade Head Experimental Forest on the Oregon coast. Measurements obtained after three different thinning treatments are presented and include stand volume, basal area, current growth rate, scar damage, crown ratio, and sapwood radius. Method of...
Cosmogenic nuclides in the Martian surface: Constraints for sample recovery and transport
NASA Technical Reports Server (NTRS)
Englert, Peter A. J.
1988-01-01
Stable and radioactive cosmogenic nuclides and radiation damage effects such as cosmic ray tracks can provide information on the surface history of Mars. A recent overview on developments in cosmogenic nuclide research for historical studies of predominantly extraterrestrial materials was published previously. The information content of cosmogenic nuclides and radiation damage effects produced in the Martian surface is based on the different ways of interaction of the primary galactic and solar cosmic radiation (GCR, SCR) and the secondary particle cascade. Generally the kind and extent of interactions as seen in the products depend on the following factors: (1) composition, energy and intensity of the primary SCR and GCR; (2) composition, energy and intensity of the GCR-induced cascade of secondary particles; (3) the target geometry, i.e., the spatial parameters of Martian surface features with respect to the primary radiation source; (4) the target chemistry, i.e., the chemical composition of the Martian surface at the sampling location down to the minor element level or lower; and (5) duration of the exposure. These factors are not independent of each other and have a major influence on sample taking strategies and techniques.
DNA damage response in nephrotoxic and ischemic kidney injury
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yan, Mingjuan; Tang, Chengyuan
DNA damage activates specific cell signaling cascades for DNA repair, cell cycle arrest, senescence, and/or cell death. Recent studies have demonstrated DNA damage response (DDR) in experimental models of acute kidney injury (AKI). In cisplatin-induced AKI or nephrotoxicity, the DDR pathway of ATR/Chk2/p53 is activated and contributes to renal tubular cell apoptosis. In ischemic AKI, DDR seems more complex and involves at least the ataxia telangiectasia mutated (ATM), a member of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, and p53; however, while ATM may promote DNA repair, p53 may trigger cell death. Targeting DDR for kidney protection in AKI therefore reliesmore » on a thorough elucidation of the DDR pathways in various forms of AKI.« less
Identification of ATM Protein Kinase Phosphorylation Sites by Mass Spectrometry.
Graham, Mark E; Lavin, Martin F; Kozlov, Sergei V
2017-01-01
ATM (ataxia-telangiectasia mutated) protein kinase is a key regulator of cellular responses to DNA damage and oxidative stress. DNA damage triggers complex cascade of signaling events leading to numerous posttranslational modification on multitude of proteins. Understanding the regulation of ATM kinase is therefore critical not only for understanding the human genetic disorder ataxia-telangiectasia and potential treatment strategies, but essential for deciphering physiological responses of cells to stress. These responses play an important role in carcinogenesis, neurodegeneration, and aging. We focus here on the identification of DNA damage inducible ATM phosphorylation sites to understand the importance of autophosphorylation in the mechanism of ATM kinase activation. We demonstrate the utility of using immunoprecipitated ATM in quantitative LC-MS/MS workflow with stable isotope dimethyl labeling of ATM peptides for identification of phosphorylation sites.
Devgan, S S; Sanal, O; Doil, C; Nakamura, K; Nahas, S A; Pettijohn, K; Bartek, J; Lukas, C; Lukas, J; Gatti, R A
2011-01-01
Maintaining genomic integrity is critical to avoid life-threatening disorders, such as premature aging, neurodegeneration and cancer. A multiprotein cascade operates at sites of DNA double-strand breaks (DSBs) to recognize, signal and repair damage. RNF168 (ring-finger nuclear factor) contributes to this emerging pathway of several E3 ubiquitin ligases that perform sequential ubiquitylations on damaged chromosomes, chromatin modifications essential for aggregation of repair complexes at the DSB sites. Here, we report the clinical and cellular phenotypes associated with a newly identified homozygous nonsense mutation in the RNF168 gene of a patient with a syndrome mimicking ataxia-telangiectasia. The mutation eliminated both of RNF168's ubiquitin-binding motifs, thus blocking progression of the ubiquitylation cascade and retention of repair proteins including tumor suppressors 53BP1 and BRCA1 at DSB sites, consistent with the observed defective DNA damage checkpoints/repair and pronounced radiosensitivity. Rapid screening for RNF168 pathway deficiency was achieved by scoring patients' lymphoblastoid cells for irradiation-induced nuclear foci containing 53BP1, a robust assay we propose for future diagnostic applications. The formation of radiation-induced DSB repair foci was rescued by ectopic expression of wild-type RNF168 in patient's cells, further causally linking the RNF168 mutation with the pathology. Clinically, this novel syndrome featured ataxia, telangiectasia, elevated alphafetoprotein, immunodeficiency, microcephaly and pulmonary failure and has implications for the differential diagnosis of autosomal recessive ataxias. PMID:21394101
Bari, Sumra; Svaldi, Diana O; Jang, Ikbeom; Shenk, Trey E; Poole, Victoria N; Lee, Taylor; Dydak, Ulrike; Rispoli, Joseph V; Nauman, Eric A; Talavage, Thomas M
2018-05-25
Long term neurological impairments due to repetitive head trauma are a growing concern for collision sport athletes. American Football has the highest rate of reported concussions among male high school athletes, a position held by soccer for female high school athletes. Recent research has shown that subconcussive events experienced by collision sport athletes can be a further significant source of accrued damage. Collision sport athletes experience hundreds of subconcussive events in a single season, and these largely go uninvestigated as they produce no overt clinical symptoms. Continued participation by these seemingly uninjured athletes is hypothesized to increase susceptibility to diagnoseable brain injury. This study paired magnetic resonance spectroscopy with head impact monitoring to quantify the relationship between metabolic changes and head acceleration event characteristics in high school-aged male football and female soccer collision sport athletes. During the period of exposure to subconcussive events, asymptomatic male (football) collision sport athletes exhibited statistically significant changes in concentrations of glutamate+glutamine (Glx) and total choline containing compounds (tCho) in dorsolateral prefrontal cortex, and female (soccer) collision sport athletes exhibited changes in glutamate+glutamine (Glx) in primary motor cortex. Neurometabolic alterations observed in football athletes during the second half of the season were found to be significantly associated with the average acceleration per head acceleration events, being best predicted by the accumulation of events exceeding 50 g. These marked deviations in neurometabolism, in the absence of overt symptoms, raise concern about the neural health of adolescent collision-sport athletes and suggest limiting exposure to head acceleration events may help to ameliorate the risk of subsequent cognitive impairment.
25 CFR 11.445 - Driving violations.
Code of Federal Regulations, 2010 CFR
2010-04-01
... violation of this section, or has been involved in a motor vehicle accident or collision resulting in property damage, personal injury, or death. (d) In the absence of an applicable tribal traffic code, the provisions of state traffic laws applicable in the state where a Court of Indian Offenses is located shall...
Proton impact charge transfer on hydantoin - Prebiotic implications
NASA Astrophysics Data System (ADS)
Bacchus-Montabonel, Marie-Christine
2016-11-01
Formation and destruction of prebiotic compounds in astrophysical environments is a major issue in reactions concerning the origin of life. Detection of hydantoin in laboratory irradiation of interstellar ice analogues has confirmed evidence of this prebiotic compound and its stability to UV radiation or collisions may be crucial. Considering the different astrophysical environments, we have investigated theoretically proton-induced collisions with hydantoin in a wide energy range, from eV in the interstellar medium, up to keV for processes involving solar wind or supernovae shock-waves protons. Results are compared to previous investigations and qualitative trends on damage under spatial radiations are suggested.
Volcano and earthquake hazards in the Crater Lake region, Oregon
Bacon, Charles R.; Mastin, Larry G.; Scott, Kevin M.; Nathenson, Manuel
1997-01-01
Crater Lake lies in a basin, or caldera, formed by collapse of the Cascade volcano known as Mount Mazama during a violent, climactic eruption about 7,700 years ago. This event dramatically changed the character of the volcano so that many potential types of future events have no precedent there. This potentially active volcanic center is contained within Crater Lake National Park, visited by 500,000 people per year, and is adjacent to the main transportation corridor east of the Cascade Range. Because a lake is now present within the most likely site of future volcanic activity, many of the hazards at Crater Lake are different from those at most other Cascade volcanoes. Also significant are many faults near Crater Lake that clearly have been active in the recent past. These faults, and historic seismicity, indicate that damaging earthquakes can occur there in the future. This report describes the various types of volcano and earthquake hazards in the Crater Lake area, estimates of the likelihood of future events, recommendations for mitigation, and a map of hazard zones. The main conclusions are summarized below.
Referees Often Miss Obvious Errors in Computer and Electronic Publications
NASA Astrophysics Data System (ADS)
de Gloucester, Paul Colin
2013-05-01
Misconduct is extensive and damaging. So-called science is prevalent. Articles resulting from so-called science are often cited in other publications. This can have damaging consequences for society and for science. The present work includes a scientometric study of 350 articles (published by the Association for Computing Machinery; Elsevier; The Institute of Electrical and Electronics Engineers, Inc.; John Wiley; Springer; Taylor & Francis; and World Scientific Publishing Co.). A lower bound of 85.4% articles are found to be incongruous. Authors cite inherently self-contradictory articles more than valid articles. Incorrect informational cascades ruin the literature's signal-to-noise ratio even for uncomplicated cases.
Referees often miss obvious errors in computer and electronic publications.
de Gloucester, Paul Colin
2013-01-01
Misconduct is extensive and damaging. So-called science is prevalent. Articles resulting from so-called science are often cited in other publications. This can have damaging consequences for society and for science. The present work includes a scientometric study of 350 articles (published by the Association for Computing Machinery; Elsevier; The Institute of Electrical and Electronics Engineers, Inc.; John Wiley; Springer; Taylor & Francis; and World Scientific Publishing Co.). A lower bound of 85.4% articles are found to be incongruous. Authors cite inherently self-contradictory articles more than valid articles. Incorrect informational cascades ruin the literature's signal-to-noise ratio even for uncomplicated cases.
Hormonal control of cold stress responses in plants.
Eremina, Marina; Rozhon, Wilfried; Poppenberger, Brigitte
2016-02-01
Cold stress responses in plants are highly sophisticated events that alter the biochemical composition of cells for protection from damage caused by low temperatures. In addition, cold stress has a profound impact on plant morphologies, causing growth repression and reduced yields. Complex signalling cascades are utilised to induce changes in cold-responsive gene expression that enable plants to withstand chilling or even freezing temperatures. These cascades are governed by the activity of plant hormones, and recent research has provided a better understanding of how cold stress responses are integrated with developmental pathways that modulate growth and initiate other events that increase cold tolerance. Information on the hormonal control of cold stress signalling is summarised to highlight the significant progress that has been made and indicate gaps that still exist in our understanding.
QCD matter thermalization at the RHIC and the LHC
NASA Astrophysics Data System (ADS)
Xu, Zhe; Cheng, Luan; El, Andrej; Gallmeister, Kai; Greiner, Carsten
2009-06-01
Employing the perturbative QCD inspired parton cascade, we investigate kinetic and chemical equilibration of the partonic matter created in central heavy ion collisions at RHIC and LHC energies. Two types of initial conditions are chosen. One is generated by the model of wounded nucleons using the PYTHIA event generator and Glauber geometry. Another is considered as a color glass condensate. We show that kinetic equilibration is almost independent of the chosen initial conditions, whereas there is a sensitive dependence for chemical equilibration. The time scale of thermalization lies between 1 and 1.5 fm/c. The final parton transverse energy obtained from BAMPS calculations is compared with the RHIC data and is estimated for the LHC energy.
Energy spectrum of sputtered uranium - A new technique
NASA Technical Reports Server (NTRS)
Weller, R. A.; Tombrello, T. A.
1978-01-01
The fission track technique for detecting U-235 has been used in conjunction with a mechanical time-of-flight spectrometer in order to measure the energy spectrum in the region 1 eV to 1 keV of material sputtered from a 93% enriched U-235 foil by 80 keV Ar-40(+) ions. The spectrum was found to exhibit a peak in the region 2-4 eV and to decrease approximately as E exp -1.77 for E not less than 100 eV. The design, construction and resolution of the mechanical spectrometer are discussed and comparisons are made between the data and the predictions of the random collision cascade model of sputtering.
Energy spectrum of sputtered uranium
NASA Technical Reports Server (NTRS)
Weller, R. A.; Tombrello, T. A.
1977-01-01
The fission track technique for detecting uranium 235 was used in conjunction with a mechanical time-of-flight spectrometer to measure the energy spectrum in the region 1 eV to 1 keV of material sputtered from a 93% enriched U-235 foil by 80 keV Ar-40(+) ions. The spectrum was found to exhibit a peak in the region 2-4 eV and to decrease approximately as E to the -1.77 power for E is approximately greater than 100 eV. The design, construction and resolution of the mechanical spectrometer are discussed and comparisons are made between the data and the predictions of the ramdom collision cascade model of sputtering.
The nucleosome: orchestrating DNA damage signaling and repair within chromatin.
Agarwal, Poonam; Miller, Kyle M
2016-10-01
DNA damage occurs within the chromatin environment, which ultimately participates in regulating DNA damage response (DDR) pathways and repair of the lesion. DNA damage activates a cascade of signaling events that extensively modulates chromatin structure and organization to coordinate DDR factor recruitment to the break and repair, whilst also promoting the maintenance of normal chromatin functions within the damaged region. For example, DDR pathways must avoid conflicts between other DNA-based processes that function within the context of chromatin, including transcription and replication. The molecular mechanisms governing the recognition, target specificity, and recruitment of DDR factors and enzymes to the fundamental repeating unit of chromatin, i.e., the nucleosome, are poorly understood. Here we present our current view of how chromatin recognition by DDR factors is achieved at the level of the nucleosome. Emerging evidence suggests that the nucleosome surface, including the nucleosome acidic patch, promotes the binding and activity of several DNA damage factors on chromatin. Thus, in addition to interactions with damaged DNA and histone modifications, nucleosome recognition by DDR factors plays a key role in orchestrating the requisite chromatin response to maintain both genome and epigenome integrity.
Quantitative Profiling of DNA Damage and Apoptotic Pathways in UV Damaged Cells Using PTMScan Direct
Stokes, Matthew P.; Silva, Jeffrey C.; Jia, Xiaoying; Lee, Kimberly A.; Polakiewicz, Roberto D.; Comb, Michael J.
2013-01-01
Traditional methods for analysis of peptides using liquid chromatography and tandem mass spectrometry (LC-MS/MS) lack the specificity to comprehensively monitor specific biological processes due to the inherent duty cycle limitations of the MS instrument and the stochastic nature of the analytical platform. PTMScan Direct is a novel, antibody-based method that allows quantitative LC-MS/MS profiling of specific peptides from proteins that reside in the same signaling pathway. New PTMScan Direct reagents have been produced that target peptides from proteins involved in DNA Damage/Cell Cycle and Apoptosis/Autophagy pathways. Together, the reagents provide access to 438 sites on 237 proteins in these signaling cascades. These reagents have been used to profile the response to UV damage of DNA in human cell lines. UV damage was shown to activate canonical DNA damage response pathways through ATM/ATR-dependent signaling, stress response pathways and induce the initiation of apoptosis, as assessed by an increase in the abundance of peptides corresponding to cleaved, activated caspases. These data demonstrate the utility of PTMScan Direct as a multiplexed assay for profiling specific cellular responses to various stimuli, such as UV damage of DNA. PMID:23344034
NASA Astrophysics Data System (ADS)
Bednarek, W.
2016-12-01
We investigate the consequences of acceleration of nuclei in jets of active galaxies not far from the surface of an accretion disk. The nuclei can be accelerated in the re-connection regions in the jet and/or at the jet boundary, between the relativistic jet and its cocoon. It is shown that the relativistic nuclei can efficiently fragment onto specific nucleons in collisions with the disk radiation. Neutrons, directed toward the accretion disk, take a significant part of energy from the relativistic nuclei. These neutrons develop a cascade in the dense accretion disk. We calculate the neutrino spectra produced in such a hadronic cascade within the accretion disk. We propose that the neutrinos produced in such a scenario, from the whole population of super-massive black holes in active galaxies, can explain the extragalactic neutrino background recently measured by the IceCube neutrino detector, provided that a 5% fraction of galaxies have an active galactic nucleus and a few percent of neutrons reach the accretion disk. We predict that the neutrino signals in the present neutrino detectors, produced in terms of such a model, will not be detectable even from the nearby radio galaxies similar to M87.
NASA Astrophysics Data System (ADS)
Carter, Evan; Hughes, A. Meredith; Daley, Cail; Flaherty, Kevin; Pan, Margaret; Schlichting, Hilke; Chiang, Eugene; MacGregor, Meredith Ann; Wilner, David; Dent, Bill; Carpenter, John; Andrews, Sean; Moor, Attila; Kospal, Agnes
2018-01-01
Debris disks are hallmarks of mature planetary systems, with second-generation dust produced via collisions between pluto-like planetesimals. The vertical structure of a debris disk encodes unique information about the dynamical state of the system, particularly at millimeter wavelengths where gravitational effects dominate over the effects of stellar radiation. We present 450 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the edge-on debris disk around AU Mic, a nearby (d = 9.91 ± 0.10 pc) M1-type star. The 0.3'' angular resolution of the data allows us to spatially resolve the scale height of the disk, complementing previous observations at a wavelength of 1.3 mm. By resolving the vertical structure of the disk at these two widely-separated frequencies, we are able to spatially resolve the spectral index and study variations in the grain size distribution as a function of disk radius. The comparison of scale heights for two different wavelengths and therefore particle sizes also constrains the velocity dispersion as a function of grain size, which allows us to probe the strengths of bodies in the collisional cascade for the first time outside the Solar System.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bednarek, W., E-mail: bednar@uni.lodz.pl
We investigate the consequences of acceleration of nuclei in jets of active galaxies not far from the surface of an accretion disk. The nuclei can be accelerated in the re-connection regions in the jet and/or at the jet boundary, between the relativistic jet and its cocoon. It is shown that the relativistic nuclei can efficiently fragment onto specific nucleons in collisions with the disk radiation. Neutrons, directed toward the accretion disk, take a significant part of energy from the relativistic nuclei. These neutrons develop a cascade in the dense accretion disk. We calculate the neutrino spectra produced in such amore » hadronic cascade within the accretion disk. We propose that the neutrinos produced in such a scenario, from the whole population of super-massive black holes in active galaxies, can explain the extragalactic neutrino background recently measured by the IceCube neutrino detector, provided that a 5% fraction of galaxies have an active galactic nucleus and a few percent of neutrons reach the accretion disk. We predict that the neutrino signals in the present neutrino detectors, produced in terms of such a model, will not be detectable even from the nearby radio galaxies similar to M87.« less
Prostate Cancer Detection by Molecular Urinalysis
2008-04-01
proteins.13 We did not specifically assess whether the urinary endoglin we detected was a result of circulating and filtered endoglin or a result of...a marker of pan-endothelial damage and angiogenesis, it is unlikely that circulating endoglin levels would be significantly affected by localized... circulating endoglin is 33 15 increased in metastatic disease states.8,10, 11 Presumably, the angiogenic cascade necessary for metastasis is
Chen, Han-sen; Chen, Xi; Li, Wen-ting; Shen, Jian-gang
2018-01-01
Reactive nitrogen species (RNS) play important roles in mediating cerebral ischemia-reperfusion injury. RNS activate multiple signaling pathways and participate in different cellular events in cerebral ischemia-reperfusion injury. Recent studies have indicated that caveolin-1 and matrix metalloproteinase (MMP) are important signaling molecules in the pathological process of ischemic brain injury. During cerebral ischemia-reperfusion, the production of nitric oxide (NO) and peroxynitrite (ONOO−), two representative RNS, down-regulates the expression of caveolin-1 (Cav-1) and, in turn, further activates nitric oxide synthase (NOS) to promote RNS generation. The increased RNS further induce MMP activation and mediate disruption of the blood-brain barrier (BBB), aggravating the brain damage in cerebral ischemia-reperfusion injury. Therefore, the feedback interaction among RNS/Cav-1/MMPs provides an amplified mechanism for aggravating ischemic brain damage during cerebral ischemia-reperfusion injury. Targeting the RNS/Cav-1/MMP pathway could be a promising therapeutic strategy for protecting against cerebral ischemia-reperfusion injury. In this mini-review article, we highlight the important role of the RNS/Cav-1/MMP signaling cascades in ischemic stroke injury and review the current progress of studies seeking therapeutic compounds targeting the RNS/Cav-1/MMP signaling cascades to attenuate cerebral ischemia-reperfusion injury. Several representative natural compounds, including calycosin-7-O-β-D-glucoside, baicalin, Momordica charantia polysaccharide (MCP), chlorogenic acid, lutein and lycopene, have shown potential for targeting the RNS/Cav-1/MMP signaling pathway to protect the brain in ischemic stroke. Therefore, the RNS/Cav-1/MMP pathway is an important therapeutic target in ischemic stroke treatment. PMID:29595191
Callaghan, James P; Martin, Parthena M; Mass, Marc J
1998-05-01
Injury to the central nervous system (CNS) provokes microglial activation and astrocytic hypertrophy at the site of damage. The signaling events that underlie these cellular responses remain unknown. Recent evidence has implicated tyrosine phosphorylation systems, in general, and the mitogen-activated protein kinase (MAP kinase) cascade, in particular, in the mediation of growth-associated events linked to neural degeneration, such as glial activation. 1 Moreover, an increase in the mRNA coding for the 14.3.3 protein, a known regulator of the MAP kinase pathway, 2 appears to be involved in methamphetamine neurotoxicity. 3 To examine the potential role of these protein kinase pathways in drug-induced damage to the CNS, we used the dopaminergic neurotoxicant, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), to damage nerve terminals in the mouse neostriatum and elicit a glial reaction. The onset of reactive gliosis then was verified by Northern blot analysis of glial fibrillary acidic protein (GFAP) mRNA and qualified by enzyme-linked immunosorbent assay (ELISA) of GFAP (protein). A single administration of MPTP (12.5 mg/kg, subcutaneously (s.c.)) to the C57B1/6J mouse resulted in a 10-fold increase in GFAP mRNA by 1 day and a 4-fold increase in GFAP (protein) by 2 days. To determine the potential role of protein tyrosine phosphorylation and MAP kinase activation in these events, blots of striatal homogenates were probed with antibodies directed against phospho-tyr 204 and phospho-thr 202, residues corresponding to the active sites of p42/44 MAP kinase. After mice were sacrificed by focused microwave irradiation to preserve steady-state phosphorylation, proteins from striatal homogenates were resolved by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Immunoblots of these samples showed a number of phosphotyrosine-labeled bands, but there were no apparent differences between control and MPTP groups. In contrast, phospho-MAP kinase was elevated over 1.5-fold, 3-6hours post MPTP. These findings are suggestive of a role of the MAP kinase cascade in the early phase of injury-induced glial activation.
The Near-Earth Orbital Debris Problem and the Challenges for Environment Remediation
NASA Technical Reports Server (NTRS)
Liou, Jer-Chyi
2012-01-01
The near-Earth space environment has been gradually polluted with orbital debris (OD) since the beginning of space activities 55 years ago. Although this problem has been known to the research community for decades, the public was, in general, unaware of the issue until the anti-satellite test conducted by China in 2007 and the collision between Cosmos 2251 and the operational Iridium 33 in 2009. The latter also underlined the potential of an ongoing collision cascade effect (the "Kessler Syndrome") in the low Earth orbit (LEO, the region below 2000 km altitude). Recent modeling results have indicated that mitigation measures commonly adopted by the international space community will be insufficient to stabilize the LEO debris population. To better limit the OD population increase, more aggressive actions must be considered. There are three options for OD environment remediation-removal of large/massive intact objects to address the root cause of the OD population growth problem, removal of 5-mm-to-1 cm debris to mitigate the main mission-ending threats for the majority of operational spacecraft, and prevention of major debris-generating collisions as a temporary means to slow down the OD population increase. The technology, engineering, and cost challenges to carry out any of these three options are monumental. It will require innovative ideas, game-changing technologies, and major collaborations at the international level to address the OD problem and preserve the near-Earth environment for future generations.
Effect of strain field on displacement cascade in tungsten studied by molecular dynamics simulation
NASA Astrophysics Data System (ADS)
Wang, D.; Gao, N.; Wang, Z. G.; Gao, X.; He, W. H.; Cui, M. H.; Pang, L. L.; Zhu, Y. B.
2016-10-01
Using atomistic methods, the coupling effect of strain field and displacement cascade in body-centered cubic (BCC) tungsten is directly simulated by molecular dynamics (MD) simulations at different temperatures. The values of the hydrostatic and uniaxial (parallel or perpendicular to primary knock-on atom (PKA) direction) strains are from -2% to 2% and the temperature is from 100 to 1000 K. Because of the annealing effect, the influence of strain on radiation damage at low temperature has been proved to be more significant than that at high temperature. When the cascade proceeds under the hydrostatic strain, the Frenkel Pair (FP) production, the fraction of defect in cluster and the average size of the defect cluster, all increase at tensile state and decrease at compressive state. When the cascade is under uniaxial strain, the effect of strain parallel to PKA direction is less than the effect of hydrostatic strain, while the effect of strain perpendicular to PKA direction can be negligible. Under the uniaxial strain along <1 1 1> direction, the SIA and SIA cluster is observed to orientate along the strain direction at tensile state and the uniaxial compressive strain with direction perpendicular to <1 1 1> has led to the similar preferred nucleation. All these results indicate that under irradiation, the tensile state should be avoided for materials used in nuclear power plants.
NASA Astrophysics Data System (ADS)
Tikhonchev, M.; Svetukhin, V.; Kapustin, P.
2017-09-01
Ab initio calculations predict high positive binding energy (˜1 eV) between niobium atoms and self-interstitial configurations in hcp zirconium. It allows the expectation of increased niobium fraction in self-interstitials formed under neutron irradiation in atomic displacement cascades. In this paper, we report the results of molecular dynamics simulation of atomic displacement cascades in Zr-0.5%Nb binary alloy and pure Zr at the temperature of 300 K. Two sets of n-body interatomic potentials have been used for the Zr-Nb system. We consider a cascade energy range of 2-20 keV. Calculations show close estimations of the average number of produced Frenkel pairs in the alloy and pure Zr. A high fraction of Nb is observed in the self-interstitial configurations. Nb is mainly detected in single self-interstitial configurations, where its fraction reaches tens of percent, i.e. more than its tenfold concentration in the matrix. The basic mechanism of this phenomenon is the trapping of mobile self-interstitial configurations by niobium. The diffusion of pure zirconium and mixed zirconium-niobium self-interstitial configurations in the zirconium matrix at 300 K has been simulated. We observe a strong dependence of the estimated diffusion coefficients and fractions of Nb in self-interstitials produced in displacement cascades on the potential.
Cumulative effects of cascade hydropower stations on total dissolved gas supersaturation.
Ma, Qian; Li, Ran; Feng, Jingjie; Lu, Jingying; Zhou, Qin
2018-05-01
Elevated levels of total dissolved gas (TDG) may occur downstream of dams during the spill process. These high levels would increase the incidence of gas bubble disease in fish and cause severe environmental impacts. With increasing numbers of cascade hydropower stations being built or planned, the cumulative effects of TDG supersaturation are becoming increasingly prominent. The TDG saturation distribution in the downstream reaches of the Jinsha River was studied to investigate the cumulative effects of TDG supersaturation resulting from the cascade hydropower stations. A comparison of the effects of the joint operation and the single operation of two hydropower stations (XLD and XJB) was performed to analyze the risk degree to fish posed by TDG supersaturation. The results showed that water with supersaturated TDG generated at the upstream cascade can be transported to the downstream power station, leading to cumulative TDG supersaturation effects. Compared with the single operation of XJB, the joint operation of both stations produced a much higher TDG saturation downstream of XJB, especially during the non-flood discharge period. Moreover, the duration of high TDG saturation and the lengths of the lethal and sub-lethal areas were much higher in the joint operation scenario, posing a greater threat to fish and severely damaging the environment. This work provides a scientific basis for strategies to reduce TDG supersaturation to the permissible level and minimize the potential risk of supersaturated TDG.
46 CFR 10.229 - Issuance of duplicate merchant mariner credentials.
Code of Federal Regulations, 2010 CFR
2010-10-01
... charge. The term “other casualty” includes any damage to a ship caused by collision, explosion, tornado, wreck, flooding, beaching, grounding, or fire; or personal loss associated with a federally declared natural disaster. (d) If a person loses a credential by means other than those noted in paragraph (c) of...
46 CFR 10.229 - Issuance of duplicate merchant mariner credentials.
Code of Federal Regulations, 2011 CFR
2011-10-01
... charge. The term “other casualty” includes any damage to a ship caused by collision, explosion, tornado, wreck, flooding, beaching, grounding, or fire; or personal loss associated with a federally declared natural disaster. (d) If a person loses a credential by means other than those noted in paragraph (c) of...
40 CFR Appendix II to Subpart S of... - As-Received Testing Vehicle Rejection Criteria
Code of Federal Regulations, 2011 CFR
2011-07-01
... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES... vehicle has been used for severe duty (trailer towing for passenger cars, snow plowing, racing) 4. The vehicle has a history of extensive collision damage or major engine repair (piston, crank, cylinder head...
40 CFR Appendix II to Subpart S of... - As-Received Testing Vehicle Rejection Criteria
Code of Federal Regulations, 2014 CFR
2014-07-01
... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES... vehicle has been used for severe duty (trailer towing for passenger cars, snow plowing, racing) 4. The vehicle has a history of extensive collision damage or major engine repair (piston, crank, cylinder head...
40 CFR Appendix II to Subpart S of... - As-Received Testing Vehicle Rejection Criteria
Code of Federal Regulations, 2013 CFR
2013-07-01
... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES... vehicle has been used for severe duty (trailer towing for passenger cars, snow plowing, racing) 4. The vehicle has a history of extensive collision damage or major engine repair (piston, crank, cylinder head...
40 CFR Appendix II to Subpart S of... - As-Received Testing Vehicle Rejection Criteria
Code of Federal Regulations, 2012 CFR
2012-07-01
... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES... vehicle has been used for severe duty (trailer towing for passenger cars, snow plowing, racing) 4. The vehicle has a history of extensive collision damage or major engine repair (piston, crank, cylinder head...
Human perceptions before and after a 50% reduction in an urban deer herd's density
David W. Henderson; Robert J. Warren; David H. Newman; J. Michael Bowker; Jennifer S. Cromwell; Jeffrey J. Jackson
2000-01-01
Overabundant white-tailed deer (Odocoileus virginianus) populations in urban and suburban areas can be controversial because of potential damage to landscape vegetation, deer-vehicle collisions, and fear over transmission of tick-borne diseases. Herd reduction is often proposed to solve these problems; however, the ability of human residents to...
Rightward Collisions and Their Association with Pseudoneglect
ERIC Educational Resources Information Center
Nicholls, Michael E. R.; Loftus, Andrea M.; Orr, Catherine A.; Barre, Natalie
2008-01-01
Whereas right parietal damage can result in left hemineglect, the general population shows a subtle neglect of the right hemispace--known as pseudoneglect. A recent study has demonstrated that people collide to the right more often and attributed this bias to pseudoneglect. [Nicholls, M. E. R., Loftus, A., Meyer, K., & Mattingley, J.B. (2007).…
The Fast Debris Evolution Model
NASA Astrophysics Data System (ADS)
Lewis, Hugh G.; Swinerd, Graham; Newland, Rebecca; Saunders, Arrun
The ‘Particles-in-a-box' (PIB) model introduced by Talent (1992) removed the need for computerintensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FaDE), employs a first-order differential equation to describe the rate at which new objects (˜ 10 cm) are added and removed from the environment. Whilst Talent (1992) based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FaDE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FaDE model has been implemented as a client-side, web-based service using Javascript embedded within a HTML document. Due to the simple nature of the algorithm, FaDE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ˜ 10 cm low Earth orbit (LEO) debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model. The results demonstrate that the FaDE model is able to capture comparable time-series of collisions and number of objects as predicted by DAMAGE in several scenarios. Further, and perhaps more importantly, its speed and flexibility allows the user to explore and understand the evolution of the space debris environment.
Characteristics of officer-involved vehicle collisions in California
Wolfe, Scott E.; Rojek, Jeff; Alpert, Geoff; Tiesman, Hope; James, Stephen
2016-01-01
Purpose The purpose of this paper is to examine the situational and individual officer characteristics of officer-involved vehicle collisions that result in fatality, injury, and non-injury outcomes. Design/methodology/approach Data on 35,840 vehicle collisions involving law enforcement officers in California occurring between January 2000 and December 2009 are examined. A descriptive analysis of collision characteristics is presented. Findings There were 39 officers killed by collisions over this study period and 7,684 officers who received some type injury. Incidents involving officers on motorcycles represented 39 percent of officer fatalities and 39 percent of severe injuries. In the case of fatalities, 33 percent of officers were reported as wearing seatbelts, 38 percent were not wearing a seatbelt, and seatbelt use was not stated in 29 percent of car fatalities. Research limitations/implications The findings only represent one state and the analysis is based on an estimated 86 percent of collisions that occurred during the study period due to missing data. Nonetheless, the results are based on a robust sample and address key limitations in the existing literature. Practical implications During the study period in California the estimated financial impact of collisions reached into the hundreds of millions of dollars when considering related fatality, injury, and vehicle damage costs combined. These impacts highlight the need for the law enforcement community to give greater attention to this issue. Originality/value At the time of this writing there was no published independent research that compares the situational and officer characteristics across fatality, injury, and non-injury outcomes in these events. The findings reported here will help inform emerging interest in this issue within the law enforcement, academic, and policy-making communities. PMID:26877704
Radiation damage free ghost diffraction with atomic resolution
Li, Zheng; Medvedev, Nikita; Chapman, Henry N.; ...
2017-12-21
The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here in this paper, we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghostmore » diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several Ångstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.« less
Radiation damage free ghost diffraction with atomic resolution
DOE Office of Scientific and Technical Information (OSTI.GOV)
Li, Zheng; Medvedev, Nikita; Chapman, Henry N.
The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here in this paper, we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghostmore » diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several Ångstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.« less
Liu, Shenbin; Mi, Wen-Li; Li, Qian; Zhang, Meng-Ting; Han, Ping; Hu, Shan; Mao-Ying, Qi-Liang; Wang, Yan-Qing
2015-11-01
Emerging evidence indicates that nerve damage-initiated neuroinflammation and immune responses, which are evidenced by the up-regulation of proinflammatory cytokines, contribute to the development of neuropathic pain. This study investigated the role of spinal interleukin (IL)-33 and its receptor ST2 in spared nerve injury (SNI)-induced neuropathic pain. The von Frey test and acetone test were performed to evaluate neuropathic pain behaviors (n = 8 to 12), and Western blot (n = 4 to 6), immunohistochemistry, real-time polymerase chain reaction (n = 5), and Bio-Plex (n = 5) assays were performed to understand the molecular mechanisms. Intrathecal administration of ST2-neutralizing antibody or ST2 gene knockout (ST2) significantly attenuated the SNI-induced mechanical and cold allodynia. On the 7th day after SNI, the expression of spinal IL-33 and ST2 was increased by 255.8 ± 27.3% and 266.4 ± 83.5% (mean ± SD), respectively. Mechanistic studies showed that the increased expression of the spinal N-methyl-D-aspartate (NMDA) receptor subunit 1 after SNI was reduced by ST2 antibody administration or ST2. The induction of nociceptive behaviors in naive mice due to recombinant IL-33 was reversed by the noncompetitive NMDA antagonist MK-801. ST2 antibody administration or ST2 markedly inhibited the increased activation of the astroglial janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) cascade and the neuronal calcium-calmodulin-dependent kinase II (CaMKII)-cyclic adenosine monophosphate response element-binding protein (CREB) cascade after SNI. Moreover, intrathecal pretreatment with the CaMKII inhibitor KN-93 or the JAK2-STAT3 cascade inhibitor AG490 attenuated recombinant IL-33-induced nociceptive behaviors and NMDA subunit 1 up-regulation in naive mice. Spinal IL-33/ST2 signaling contributes to neuropathic pain by activating the astroglial JAK2-STAT3 cascade and the neuronal CaMKII-CREB cascade.
Impact of Short-Range Forces on Defect Production from High-Energy Collisions
Stoller, R. E.; Tamm, A.; Béland, L. K.; ...
2016-04-25
Primary radiation damage formation in solid materials typically involves collisions between atoms that have up to a few hundred keV of kinetic energy. The distance between two colliding atoms can approach 0.05 nm during these collisions. At such small atomic separations, force fields fitted to equilibrium properties tend to significantly underestimate the potential energy of the colliding dimer. To enable molecular dynamics simulations of high-energy collisions, it is common practice to use a screened Coulomb force field to describe the interactions and to smoothly join this to the equilibrium force field at a suitable interatomic spacing. But, there is nomore » accepted standard method for choosing the parameters used in the joining process, and our results prove that defect production is sensitive to how the force fields are linked. A new procedure is presented that involves the use of ab initio calculations to determine the magnitude and spatial dependence of the pair interactions at intermediate distances, along with systematic criteria for choosing the joining parameters. Results are presented for the case of nickel, which demonstrate the use and validity of the procedure.« less
Chatrchyan, Serguei
2014-04-18
Results are reported from a search for supersymmetry in pp collisions at a center-of-mass energy of 8 TeV, based on events with a single isolated lepton (electron or muon) and multiple jets, at least two of which are identified as b jets. The data sample corresponds to an integrated luminosity of 19.3 inverse femtobarns recorded by the CMS experiment at the LHC in 2012. The search is motivated by supersymmetric models that involve strong-production processes and cascade decays of new particles. The resulting final states contain multiple jets as well as missing transverse momentum from weakly interacting particles. The eventmore » yields, observed across several kinematic regions, are consistent with the expectations from standard model processes. Thus the results are interpreted in the context of simplified supersymmetric scenarios with pair production of gluinos, where each gluino decays to a top quark-antiquark pair and the lightest neutralino. For the case of decays via virtual top squarks, gluinos with a mass smaller than 1.26 TeV are excluded for low neutralino masses.« less
Charge exchange of highly charged argon ions as a function of projectile energy
NASA Astrophysics Data System (ADS)
Allen, F. I.; Biedermann, C.; Radtke, R.; Fussmann, G.
2007-03-01
X-ray emission of highly charged argon ions following charge exchange collisions with argon atoms has been measured as a function of projectile energy. The ions are extracted from the Electron Beam Ion Trap (EBIT) in Berlin and selected according to their massto-charge ratios. Experiments focussed on hydrogen-like and bare argon ions which were decelerated from 125q eV/amu to below 0.25q eV/amu prior to interaction with an argon gas target. The x-ray spectra recorded probe the cascading transitions resulting from electron capture into Rydberg states and are found to vary significantly with collision velocity. This indicates a shift in the orbital angular momentum of the capture state. Hardness ratios are observed to increase with decreasing projectile energy though at a rate which differs from the results of simulations. For comparison, measurements of the x-ray emission following charge exchange within the trap were carried out and are in agreement with the findings of the EBIT group at LLNL. Both of these in situ measurements, however, are in discrepancy with the results of the experiments using extracted ions.
NASA Astrophysics Data System (ADS)
Cumbee, R. S.; Mullen, P. D.; Lyons, D.; Shelton, R. L.; Fogle, M.; Schultz, D. R.; Stancil, P. C.
2018-01-01
The fundamental collisional process of charge exchange (CX) has been established as a primary source of X-ray emission from the heliosphere, planetary exospheres, and supernova remnants. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly excited, high-charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays. To provide reliable CX-induced X-ray spectral models to realistically simulate these environments, line ratios and spectra are computed using theoretical CX cross sections obtained with the multi-channel Landau-Zener, atomic-orbital close-coupling, molecular-orbital close-coupling, and classical trajectory Monte Carlo methods for various collisional velocities relevant to astrophysics. X-ray spectra were computed for collisions of bare and H-like C to Al ions with H, He, and H2 with results compared to available experimental data. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant and the heliosphere are shown as examples with ion velocity dependence.
NASA Technical Reports Server (NTRS)
Richards, P. G.; Torr, D. G.
1981-01-01
A simplified method for the evaluation of theoretical photoelectron fluxes in the upper atmosphere resulting from the solar radiation at 304 A is presented. The calculation is based on considerations of primary and cascade (secondary) photoelectron production in the two-stream model, where photoelectron transport is described by two electron streams, one moving up and one moving down, and of loss rates due to collisions with neutral gases and thermal electrons. The calculation is illustrated for the case of photoelectrons at an energy of 24.5 eV, and it is noted that the 24.5-eV photoelectron flux may be used to monitor variations in the solar 304 A flux. Theoretical calculations based on various ionization and excitation cross sections of Banks et al. (1974) are shown to be in generally good agreement with AE-E measurements taken between 200 and 235 km, however the use of more recent, larger cross sections leads to photoelectron values a factor of two smaller than observations but in agreement with previous calculations. It is concluded that a final resolution of the photoelectron problem may depend on a reevaluation of the inelastic electron collision cross sections.
Non-equilibrium processes in p + Ag collisions at GeV energies
NASA Astrophysics Data System (ADS)
Fidelus, M.; Filges, D.; Goldenbaum, F.; Jarczyk, L.; Kamys, B.; Kistryn, M.; Kistryn, St.; Kozik, E.; Kulessa, P.; Machner, H.; Magiera, A.; Piskor-Ignatowicz, B.; Pysz, K.; Rudy, Z.; Sharma, Sushil K.; Siudak, R.; Wojciechowski, M.; PISA Collaboration
2017-12-01
The double differential spectra d2σ /d Ω d E of p , d , t , 3,4,6He, 6,7,8,9Li, 7,9,10Be, and 10,11,12B were measured at seven scattering angles, 15.6∘, 20∘, 35∘, 50∘, 65∘, 80∘, and 100∘, in the laboratory system for proton induced reactions on a silver target. Measurements were done for three proton energies: 1.2, 1.9, and 2.5 GeV. The experimental data were compared to calculations performed by means of two-step theoretical microscopic models. The first step of the reaction was described by the intranuclear cascade model incl4.6 and the second one by four different models (ABLA07, GEM2, gemini++, and SMM) using their standard parameter settings. Systematic deviations of the data from predictions of the models were observed. The deviations were especially large for the forward scattering angles and for the kinetic energy of emitted particles in the range from about 50 to 150 MeV. This suggests that some important non-equilibrium mechanism is lacking in the present day microscopic models of proton-nucleus collisions in the studied beam energy range.
Structure and Bonding in Noncrystalline Solids Abstracts
1983-06-02
displacement cascades are unlikely. Related damage studies as diffuse X- ray scattering, magnetic susceptibility and positron - annihilation lifetime...the positron annihilation lifetime data; diffuse X-ray scattering studies give evidence for "amorphized" clusters in neutron but not in elec-ron...feldspar glasses and glasses in the system CaO- MgO -SiO 2 . These results indicate that the nearest-neighbor and next- nearest-neighbor environments are very
Machiavelli, Leticia I; Poliandri, Ariel H; Quinteros, Fernanda A; Cabilla, Jimena P; Duvilanski, Beatriz H
2007-03-01
We previously showed that long-term exposure of anterior pituitary cells to nitric oxide (NO) induces apoptosis. The intracellular signals underlying this effect remained unclear. In this study, we searched for possible mechanisms involved in the early stages of the NO apoptotic cascade. Caspase 3 was activated by NO with no apparent disruption of mitochondrial membrane potential. NO caused a rapid increase of reactive oxygen species (ROS), and this increase seems to be dependent of mitochondrial electron transport chain. The antioxidant N-acetyl-cysteine avoided ROS increase, prevented the NO-induced caspase 3 activation, and reduced the NO apoptotic effect. Catalase was inactivated by NO, while glutathione peroxidase (GPx) activity and reduced glutathione (GSH) were not modified at first, but increased at later times of NO exposure. The increase of GSH level is important for the scavenging of the NO-induced ROS overproduction. Our results indicate that ROS have an essential role as a trigger of the NO apoptotic cascade in anterior pituitary cells. The permanent inhibition of catalase may strengthen the oxidative damage induced by NO. GPx activity and GSH level augment in response to the oxidative damage, though this increase seems not to be enough to rescue the cells from the NO effect.
Marchesi, Vincent T
2016-02-01
Amyloid deposits are a characteristic feature of advanced Alzheimer dementia (AD), but whether they initiate the disease or are a consequence of it remains an unsettled question. To explore an alternative pathogenic mechanism, I propose that the triggering events that begin the pathogenic cascade are not amyloid deposits but damaged blood vessels caused by inflammatory reactions that lead to ischemia, amyloid accumulation, axonal degeneration, synaptic loss, and eventually irreversible neuronal cell death. Inflammation and blood vessel damage are well recognized complications of AD, but what causes them and why the cerebral microvasculature is affected have never been adequately addressed. Because heritable autosomal dominant mutations of NLRP3, APP, TREX1, NOTCH3, and Col4A1 are known to provoke inflammatory reactions and damage the brain in a wide variety of diseases, I propose that one or more low abundant, gain-of-function somatic mutations of the same 5 gene families damage the microvasculature of the brain that leads to dementia. This implies that the pathogenic triggers that lead to AD are derived not from external invaders or amyloid but from oxidative damage of our own genes. © FASEB.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Qi, Junjian; Pfenninger, Stefan
In this paper, we propose a strategy to control the self-organizing dynamics of the Bak-Tang-Wiesenfeld (BTW) sandpile model on complex networks by allowing some degree of failure tolerance for the nodes and introducing additional active dissipation while taking the risk of possible node damage. We show that the probability for large cascades significantly increases or decreases respectively when the risk for node damage outweighs the active dissipation and when the active dissipation outweighs the risk for node damage. By considering the potential additional risk from node damage, a non-trivial optimal active dissipation control strategy which minimizes the total cost inmore » the system can be obtained. Under some conditions the introduced control strategy can decrease the total cost in the system compared to the uncontrolled model. Moreover, when the probability of damaging a node experiencing failure tolerance is greater than the critical value, then no matter how successful the active dissipation control is, the total cost of the system will have to increase. This critical damage probability can be used as an indicator of the robustness of a network or system. Copyright (C) EPLA, 2015« less
Dry eye disease: an immune-mediated ocular surface disorder
Stevenson, William; Chauhan, Sunil K.; Dana, Reza
2013-01-01
Dry eye disease is a multifactorial disorder of the tears and ocular surface characterized by symptoms of dryness and irritation. Although the pathogenesis of dry eye disease is not fully understood, it is recognized that inflammation has a prominent role in the development and propagation of this debilitating condition. Factors that adversely affect tear film stability and osmolarity can induce ocular surface damage and initiate an inflammatory cascade that generates innate and adaptive immune responses. These immunoinflammatory responses lead to further ocular surface damage and the development of a self-perpetuating inflammatory cycle. Herein, we review the fundamental links between inflammation and dry eye disease and discuss the clinical implications of inflammation in disease management. PMID:22232476
NASA Technical Reports Server (NTRS)
Marshall, C. J.; Ladbury, R.; Marshall, P. W.; Reed, R. A.; Howe, C.; Weller, B.; Mendenhall, M.; Waczynski, A.; Jordan, T. M.; Fodness, B.
2006-01-01
This paper presents a combined Monte Carlo and analytic approach to the calculation of the pixel-to-pixel distribution of proton-induced damage in a HgCdTe sensor array and compares the results to measured dark current distributions after damage by 63 MeV protons. The moments of the Coulombic, nuclear elastic and nuclear inelastic damage distribution were extracted from Monte Carlo simulations and combined to form a damage distribution using the analytic techniques first described in [I]. The calculations show that the high energy recoils from the nuclear inelastic reactions (calculated using the Monte Car10 code MCNPX [2]) produce a pronounced skewing of the damage energy distribution. The nuclear elastic component (also calculated using the MCNPX) has a negligible effect on the shape of the damage distribution. The Coulombic contribution was calculated using MRED [3,4], a Geant4 [4,5] application. The comparison with the dark current distribution strongly suggests that mechanisms which are not linearly correlated with nonionizing damage produced according to collision kinematics are responsible for the observed dark current increases. This has important implications for the process of predicting the on-orbit dark current response of the HgCdTe sensor array.
NASA Astrophysics Data System (ADS)
Straub, Jeremy
2014-06-01
Resident space objects (RSOs) pose a significant threat to orbital assets. Due to high relative velocities, even a small RSO can cause significant damage to an object that it strikes. Worse, in many cases a collision may create numerous additional RSOs, if the impacted object shatters apart. These new RSOs will have heterogeneous mass, size and orbital characteristics. Collision avoidance systems (CASs) are used to maneuver spacecraft out of the path of RSOs to prevent these impacts. A RSO CAS must be validated to ensure that it is able to perform effectively given a virtually unlimited number of strike scenarios. This paper presents work on the creation of a testing environment and AI testing routine that can be utilized to perform verification and validation activities for cyber-physical systems. It reviews prior work on automated and autonomous testing. Comparative performance (relative to the performance of a human tester) is discussed.
Protection of host cells by complement regulators.
Schmidt, Christoph Q; Lambris, John D; Ricklin, Daniel
2016-11-01
The complement cascade is an ancient immune-surveillance system that not only provides protection from pathogen invasion but has also evolved to participate in physiological processes to maintain tissue homeostasis. The alternative pathway (AP) of complement activation is the evolutionarily oldest part of this innate immune cascade. It is unique in that it is continuously activated at a low level and arbitrarily probes foreign, modified-self, and also unaltered self-structures. This indiscriminate activation necessitates the presence of preformed regulators on autologous surfaces to spare self-cells from the undirected nature of AP activation. Although the other two canonical complement activation routes, the classical and lectin pathways, initiate the cascade more specifically through pattern recognition, their activity still needs to be tightly controlled to avoid excessive reactivity. It is the perpetual duty of complement regulators to protect the self from damage inflicted by inadequate complement activation. Here, we review the role of complement regulators as preformed mediators of defense, explain their common and specialized functions, and discuss selected cases in which alterations in complement regulators lead to disease. Finally, rational engineering approaches using natural complement inhibitors as potential therapeutics are highlighted. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Driben, Rodislav; Mitschke, Fedor; Zhavoronkov, Nickolai
2010-12-06
The complex mechanism of multiple interactions between solitary and dispersive waves at the advanced stage of supercontinuum generation in photonic crystal fiber is studied in experiment and numerical simulations. Injection of high power negatively chirped pulses near zero dispersion frequency results in an effective soliton fission process with multiple interactions between red shifted Raman solitons and dispersive waves. These interactions may result in relative acceleration of solitons with further collisions between them of quasi-elastic or quasi-plastic kinds. In the spectral domain these processes result in enhancement of certain wavelength regions within the spectrum or development of a new significant band at the long wavelength side of the spectrum.
Dissipation of ionospheric irregularities by wave-particle and collisional interactions
NASA Technical Reports Server (NTRS)
Bernhardt, P. A.; Pongratz, M. B.; Gray, S. P.; Thomsen, M. F.
1982-01-01
The nonlinear dissipation of plasma irregularities aligned parallel to an ambient magnetic field is studied numerically using a model which employs both wave-particle and collisional diffusion. A wave-particle diffusion coefficient derived from a local theory of the universal drift instability is used. This coefficient is effective in regions of nonzero plasma gradients and produces triangular-shaped irregularities with spectra which vary as f to the -4th, where f is the spatial frequency. Collisional diffusion acts rapidly on the vertices of the irregularities to reduce their amplitude. The simultaneous action of the two dissipative processes is more efficient than collisions acting alone. In this model, wave-particle diffusion mimics the forward cascade process of wave-wave coupling.
Magnitude of, trends in, and associated factors of road traffic collision in central Ethiopia.
Asefa, Fekede; Assefa, Demeke; Tesfaye, Gezahegn
2014-10-15
Road traffic collision (RTC) is one of many public health problems. Globally, about 1.2 million people die due to RTCs every year. Of these, 85% reside in low- and middle-income countries. Despite low road network density and vehicle ownership, Ethiopia has a relatively high collision record. Collisions in the Addis Ababa and Oromia Regions account for 58% of all fatal collisions in Ethiopia. The aim of this study was to assess the magnitude of, trends in and factors associated with RTCs in central Ethiopia. A retrospective study was conducted using relevant police reports obtained from eight police stations found between Akaki and Adama towns located in central Ethiopia. The study included reports from July 2007 to June 2012. Both quantitative and qualitative techniques were employed, and bivariate and multivariate analyses were performed to identify the factors associated with the RTCs. From July 2007 to June 2012, 2,335 collisions were registered, though the outcomes of 24 of these crashes were not recorded. Among these collisions, 389 (16.7%) resulted in death, 316 (13.5%) brought about severe injuries, 290 (12.4%) caused slight injuries, and 1,316 (56.4%) caused property damage. These collisions affected about 1,745 individuals. While 515 (29.5%) people died, 549 (31.5%) were severely injured, and the remaining 681 (39%) were slightly injured. Driving at midnight [AOR 1.67, 95% CI; 1.2-2.4], driving above the speed limit [AOR 5.3, 95% CI; 2.9-9.6], failing to give priority for other vehicles and pedestrians [AOR 5.03, 95% CI; 2.3-9.3], and vehicular technical problems [AOR 19, 95% CI; 6.4-56] were determinants of RTC fatality. RTCs steadily increased in the study area over this period of time. This calls for urgent interventions. Ensuring that drivers obey traffic rules and enforcing the speed limit appear to be the most critical parts of necessary interventions.
Predicting effects of structural stress in a genome-reduced model bacterial metabolism
NASA Astrophysics Data System (ADS)
Güell, Oriol; Sagués, Francesc; Serrano, M. Ángeles
2012-08-01
Mycoplasma pneumoniae is a human pathogen recently proposed as a genome-reduced model for bacterial systems biology. Here, we study the response of its metabolic network to different forms of structural stress, including removal of individual and pairs of reactions and knockout of genes and clusters of co-expressed genes. Our results reveal a network architecture as robust as that of other model bacteria regarding multiple failures, although less robust against individual reaction inactivation. Interestingly, metabolite motifs associated to reactions can predict the propagation of inactivation cascades and damage amplification effects arising in double knockouts. We also detect a significant correlation between gene essentiality and damages produced by single gene knockouts, and find that genes controlling high-damage reactions tend to be expressed independently of each other, a functional switch mechanism that, simultaneously, acts as a genetic firewall to protect metabolism. Prediction of failure propagation is crucial for metabolic engineering or disease treatment.
Molina-Vicenty, Irma L; Santiago-Sánchez, Michelaldemar; Vélez-Miró, Iván; Motta-Valencia, Keryl
2016-09-01
Traumatic brain injury (TBI) is defined as damage to the brain resulting from an external force. TBI, a global leading cause of death and disability, is associated with serious social, economic, and health problems. In cases of mild-to-moderate brain damage, conventional anatomical imaging modalities may or may not detect the cascade of metabolic changes that have occurred or are occurring at the intracellular level. Functional nuclear medicine imaging and neurophysiological parameters can be used to characterize brain damage, as the former provides direct visualization of brain function, even in the absence of overt behavioral manifestations or anatomical findings. We report the case of a 30-year-old Hispanic male veteran who, after 2 traumatic brain injury events, developed cognitive and neuropsychological problems with no clear etiology in the presence of negative computed tomography (CT) findings.
Homeostatic regulation of meiotic DSB formation by ATM/ATR
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie
2014-11-15
Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction ofmore » numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Xue, Haizhou; Zarkadoula, Eva; Sachan, Ritesh
Latent ion tracks created by energetic heavy ions (12 MeV Ti to 946 MeV Au) in single crystal SrTiO 3 are investigated in this paper using Rutherford backscattering spectrometry and scanning transmission electron microscopy. The results demonstrate that pre-existing irradiation damage, introduced via elastic collision processes, interacts synergistically with the electronic energy deposition from energetic heavy ions to enhance formation of latent ion tracks. The average amorphous cross-section increases with the level of pre-damage and is linearly proportional to the electronic energy loss of the ions, with a slope dependent on the pre-damage level. For the highest energy ions (629more » MeV Xe and 946 MeV Au), the tracks are continuous over the pre-damaged depth, but become discontinuous beyond the pre-damaged region. Finally, this work provides new understanding and insights on ion-solid interactions that significantly impact the interpretation of latent track formation processes, models of amorphization, and the fabrication of electro-ceramic devices.« less
Xue, Haizhou; Zarkadoula, Eva; Sachan, Ritesh; ...
2018-03-20
Latent ion tracks created by energetic heavy ions (12 MeV Ti to 946 MeV Au) in single crystal SrTiO 3 are investigated in this paper using Rutherford backscattering spectrometry and scanning transmission electron microscopy. The results demonstrate that pre-existing irradiation damage, introduced via elastic collision processes, interacts synergistically with the electronic energy deposition from energetic heavy ions to enhance formation of latent ion tracks. The average amorphous cross-section increases with the level of pre-damage and is linearly proportional to the electronic energy loss of the ions, with a slope dependent on the pre-damage level. For the highest energy ions (629more » MeV Xe and 946 MeV Au), the tracks are continuous over the pre-damaged depth, but become discontinuous beyond the pre-damaged region. Finally, this work provides new understanding and insights on ion-solid interactions that significantly impact the interpretation of latent track formation processes, models of amorphization, and the fabrication of electro-ceramic devices.« less
Wiedenhoft, Heather; Hayashi, Lauren; Coffin, Allison B.
2017-01-01
Inner ear hair cell death leads to sensorineural hearing loss and can be a direct consequence of aminoglycoside antibiotic treatment. Aminoglycosides such as gentamicin are effective therapy for serious Gram-negative bacterial infections such as some forms of meningitis, pneumonia, and sepsis. Aminoglycosides enter hair cells through mechanotransduction channels at the apical end of hair bundles and initiate intrinsic cell death cascades, but the precise cell signaling that leads to hair cell death is incompletely understood. Here, we examine the cell death pathways involved in aminoglycoside damage using the zebrafish (Danio rerio). The zebrafish lateral line contains hair cell-bearing organs called neuromasts that are homologous to hair cells of the mammalian inner ear and represents an excellent model to study ototoxicity. Based on previous research demonstrating a role for p53, Bcl2 signaling, autophagy, and proteasomal degradation in aminoglycoside-damaged hair cells, we used the Cytoscape GeneMANIA Database to identify additional proteins that might play a role in neomycin or gentamicin ototoxicity. Our bioinformatics analysis identified the pro-survival proteins phosphoinositide-dependent kinase-1 (PDK1) and X-linked inhibitor of apoptosis protein (Xiap) as potential mediators of gentamicin-induced hair cell damage. Pharmacological inhibition of PDK1 or its downstream mediator protein kinase C facilitated gentamicin toxicity, as did Xiap mutation, suggesting that both PI3K and endogenous Xiap confer protection. Surprisingly, aminoglycoside-induced hair cell death was highly attenuated in wild type Tupfel long-fin (TL fish; the background strain for the Xiap mutant line) compared to wild type ∗AB zebrafish. Pharmacologic manipulation of p53 suggested that the strain difference might result from decreased p53 in TL hair cells, allowing for increased hair cell survival. Overall, our studies identified additional steps in the cell death cascade triggered by aminoglycoside damage, suggesting possible drug targets to combat hearing loss resulting from aminoglycoside exposure. PMID:29093665
Impact of the New Optimal Rules for Arbitration of Disputers Relating to Space Debris Controversies
NASA Astrophysics Data System (ADS)
Force, Melissa K.
2013-09-01
The mechanisms and procedures for settlement of disputes arising from space debris collision damage, such as that suffered by the Russian Cosmos and US Iridium satellites in 2009, are highly political, nonbinding and unpredictable - all of which contributes to the uncertainty that increases the costs of financing and insuring those endeavors that take place in near-Earth space, especially in Low Earth Orbit. Dispute settlement mechanisms can be found in the 1967 Outer Space Treaty, which provides for consultations in cases involving potentially harmful interference with activities of States parties, and in the 1972 Liability Convention which permits but does not require States - not non-governmental entities - to pursue claims in a resolution process that is nonbinding (unless otherwise agreed.) There are soft- law mechanisms to control the growth of space debris, such as the voluntary 2008 United Nations Space Debris Mitigation Guidelines, and international law and the principles of equity and justice generally provide reparation to restore a person, State or organization to the condition which would have existed if damage had not occurred, but only if all agree to a specific tribunal or international court; even then, parties may be bound by the result only if agreed and enforcement of the award internationally remains uncertain. In all, the dispute resolution process for damage resulting from inevitable future damage from space debris collisions is highly unsatisfactory. However, the Administrative Council of the Permanent Court of Arbitration's recently adopted Optional Rules for the Arbitration of Disputes Relating to Outer Space Activities are, as of yet, untested, and this article will provide an overview of the process, explore the ways in which they fill in gaps in the previous patchwork of systems and analyze the benefits and shortcomings of the new Outer Space Optional Rules.
NASA Astrophysics Data System (ADS)
Liou, J.-C.
The intentional breakup of Fengyun-1C on 11 January 2007 created the most severe orbital debris cloud in history. More than 2500 large fragments were identified and tracked by the U.S. Space Surveillance Network by the end of the year. The altitude where the event occurred was probably the worst location for a major breakup in the low Earth orbit (LEO) region, since it was already highly populated with operational satellites and debris generated from previous breakups. The addition of so many fragments not only poses a realistic threat to operational satellites in the region, but also increases the instability (i.e., collision cascade effect) of the debris population there. Preliminary analysis of the large Fengyun-1C fragments indicates that their size and area-tomass ratio (A/M) distributions are very different from those of other known events. About half of the fragments appear to be composed of light-weight materials and more than 100 of them have A/M values exceeding 1 m2 /kg, consistent with thermal blanket pieces. In addition, the orbital elements of the fragments suggest non-trivial velocity gain by the fragment cloud during the impact. These important characteristics were incorporated into a numerical simulation to assess the long-term impact of the Fengyun-1C fragments to the LEO debris environment. The main objectives of the simulation were to evaluate (1) the collision probabilities between the Fengyun-1C fragments and the rest of the catalog population and (2) the collision activities and population growth in the region in the next 100 years.
VizieR Online Data Catalog: X-ray line ratios for diverse ion collisions (Mullen+, 2017)
NASA Astrophysics Data System (ADS)
Mullen, P. D.; Cumbee, R. S.; Lyons, D.; Gu, L.; Kaastra, J.; Shelton, R. L.; Stancil, P. C.
2018-03-01
Charge exchange (CX) has emerged in X-ray emission modeling as a significant process that must be considered in many astrophysical environments- particularly comets. Comets host an interaction between solar wind ions and cometary neutrals to promote solar wind charge exchange (SWCX). X-ray observatories provide astronomers and astrophysicists with data for many X-ray emitting comets that are impossible to accurately model without reliable CX data. Here, we utilize a streamlined set of computer programs that incorporate the multi-channel Landau-Zener theory and a cascade model for X-ray emission to generate cross sections and X-ray line ratios for a variety of bare and non-bare ion single electron capture (SEC) collisions. Namely, we consider collisions between the solar wind constituent bare and H-like ions of C, N, O, Ne, Na, Mg, Al, and Si and the cometary neutrals H2O, CO, CO2, OH, and O. To exemplify the application of this data, we model the X-ray emission of Comet C/2000 WM1 (linear) using the CX package in SPEX and find excellent agreement with observations made with the XMM-Newton RGS detector. Our analyses show that the X-ray intensity is dominated by SWCX with H, while H2O plays a secondary role. This is the first time, to our knowledge, that CX cross sections have been implemented into a X-ray spectral fitting package to determine the H to H2O ratio in cometary atmospheres. The CX data sets are incorporated into the modeling packages SPEX and Kronos. (1 data file).
Active Debris Removal of Multiple Priority Targets
NASA Astrophysics Data System (ADS)
Braun, Vitali; Flegel, Sven Kevin; Vörsmann, Peter; Wiedemann, Carsten; Gelhaus, Johannes; Moeckel, Marek; Kebschull, Christopher
2012-07-01
Today's space debris environment shows major concentrations of objects within distinct orbital regions for nearly all size regimes. The most critical region is found at orbital altitudes near 800 kilometers with high declinations. Within this region many satellites are operated in so called sun-synchronous orbits (SSO). Among those, there are Earth observation, communication and weather satellites. Due to the orbital geometry, head-on encounters with relative velocities of about 15 km/s are most probable and would thus result in highly energetic collisions, which are often referred to as catastrophic collisions, leading to the complete fragmentation of the participating objects. So called feedback collisions can then be triggered by the newly generated fragments, thus leading to a further population increase in the affected orbital region. This effect is known as the Kessler syndrome. Current studies show that catastrophic collisions are not a major problem today, but will become the main process for debris generation within the SSO region in the near future, even without any future launches. In order to avoid this effect, objects with a major impact on collisional cascading have to be actively removed from the critical region after their end of life. Not having the capability to perform an end-of-life maneuver in order to transfer to a graveyard orbit or to de-orbit, many satellites and rocket bodies would have to be de-orbited within a dedicated mission. In such a mission, a service satellite would perform a de-orbit maneuver, after having docked to a specific target. In this paper several systems, e.g. chemical and electrical engines are analysed with the main focus on removing multiple targets within one single mission. The service satellite has to undock from the previously de-orbited target in order to start the rendezvous and docking phase for a subsequent target. The targets are chosen from a previously defined priority list in order to enhance the mission efficiency. Total mission time and system mass shall enable the evaluation of the different concepts.
Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Fujii, Kentaro; Watanabe, Ritsuko
2016-11-01
To simulate the deceleration processes of secondary electrons produced by a high-energy Auger electron in water, and particularly to focus on the spatial and temporal distributions of the secondary electron and the collision events (e.g. ionization, electronic excitation, and dissociative electron attachment) that are involved in the multiplication of lesions at sites of DNA damage. We developed a dynamic Monte Carlo code that considers the Coulombic force between an ejected electron and its parent cation produced by the Auger electron in water. Thus our code can simulate some return electrons to the parent cations. Using the code, we calculated to within the order of femtoseconds the temporal evolution of collision events, the mean energy, and the mean traveling distance (including its spatial probability distribution) of the electron at an ejected energy of 20 eV. Some of the decelerating electrons in water in the Coulombic field were attracted to the ionized atoms (cations) by the Coulombic force within hundreds of femtoseconds, although the force did not significantly enhance the number of ionization, electronic excitation, and dissociative electron attachment collision events leading to water radiolysis. The secondary electrons are decelerated in water by the Coulombic force and recombined to the ionized atoms (cations). Furthermore, the some return electrons might be prehydrated in water layer near the parent cation in DNA if the electrons might be emitted from the DNA. The prehydrated electron originated from the return electron might play a significant role in inducing DNA damage.
NASA Technical Reports Server (NTRS)
Marshall, C. J.; Marshall, P. W.; Howe, C. L.; Reed, R. A.; Weller, R. A.; Mendenhall, M.; Waczynski, A.; Ladbury, R.; Jordan, T. M.
2007-01-01
This paper presents a combined Monte Carlo and analytic approach to the calculation of the pixel-to-pixel distribution of proton-induced damage in a HgCdTe sensor array and compares the results to measured dark current distributions after damage by 63 MeV protons. The moments of the Coulombic, nuclear elastic and nuclear inelastic damage distributions were extracted from Monte Carlo simulations and combined to form a damage distribution using the analytic techniques first described in [1]. The calculations show that the high energy recoils from the nuclear inelastic reactions (calculated using the Monte Carlo code MCNPX [2]) produce a pronounced skewing of the damage energy distribution. While the nuclear elastic component (also calculated using the MCNPX) contributes only a small fraction of the total nonionizing damage energy, its inclusion in the shape of the damage across the array is significant. The Coulombic contribution was calculated using MRED [3-5], a Geant4 [4,6] application. The comparison with the dark current distribution strongly suggests that mechanisms which are not linearly correlated with nonionizing damage produced according to collision kinematics are responsible for the observed dark current increases. This has important implications for the process of predicting the on-orbit dark current response of the HgCdTe sensor array.
[The characteristics of computer simulation of traffic accidents].
Zou, Dong-Hua; Liu, Ning-Guo; Chen, Jian-Guo; Jin, Xian-Long; Zhang, Xiao-Yun; Zhang, Jian-Hua; Chen, Yi-Jiu
2008-12-01
To reconstruct the collision process of traffic accident and the injury mode of the victim by computer simulation technology in forensic assessment of traffic accident. Forty actual accidents were reconstructed by stimulation software and high performance computer based on analysis of the trace evidences at the scene, damage of the vehicles and injury of the victims, with 2 cases discussed in details. The reconstruction correlated very well in 28 cases, well in 9 cases, and suboptimal in 3 cases with the above parameters. Accurate reconstruction of the accident would be helpful for assessment of the injury mechanism of the victims. Reconstruction of the collision process of traffic accident and the injury mechanism of the victim by computer simulation is useful in traffic accident assessment.
Radiation Enhanced Absorption of Frank Loops by Nanovoids in Cu
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chen, Youxing; Zhang, Xinghang; Wang, Jian
Neutron and heavy ion irradiation generally induces voids in metallic materials, and continuous radiations typically result in void swelling and mechanical failure of the irradiated materials. Recent experiments showed that nanovoids in nanotwinned copper could act as sinks for radiation-induced Frank loops, significantly mitigating radiation damage [Y. Chen et al., Nat. Commun. 6:7036 (2015)]. In this paper, we report on structural evolution of Frank loops under cascades and address the role of nanovoids in absorbing Frank loops in detail by using molecular dynamics simulations. Results show that a stand-alone Frank loop is stable under cascades. When Frank loops are adjacentmore » to nanovoids, the diffusion of a group of atoms from the loop into nanovoids is accomplished via the formation and propagation of dislocation loops. The loop-nanovoid interactions result in the shrinkage of the nanovoids and the Frank loops.« less
MD simulation of plastic deformation nucleation in stressed crystallites under irradiation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Korchuganov, A. V., E-mail: avkor@ispms.tsc.ru; Zolnikov, K. P., E-mail: kost@ispms.tsc.ru; Kryzhevich, D. S., E-mail: kryzhev@ispms.tsc.ru
2016-12-15
The investigation of plastic deformation nucleation in metals and alloys under irradiation and mechanical loading is one of the topical issues of materials science. Specific features of nucleation and evolution of the defect system in stressed and irradiated iron, vanadium, and copper crystallites were studied by molecular dynamics simulation. Mechanical loading was performed in such a way that the modeled crystallite volume remained unchanged. The energy of the primary knock-on atom initiating a cascade of atomic displacements in a stressed crystallite was varied from 0.05 to 50 keV. It was found that atomic displacement cascades might cause global structural transformationsmore » in a region far larger than the radiation-damaged area. These changes are similar to the ones occurring in the process of mechanical loading of samples. They are implemented by twinning (in iron and vanadium) or through the formation of partial dislocation loops (in copper).« less
Radiation Enhanced Absorption of Frank Loops by Nanovoids in Cu
Chen, Youxing; Zhang, Xinghang; Wang, Jian
2016-11-01
Neutron and heavy ion irradiation generally induces voids in metallic materials, and continuous radiations typically result in void swelling and mechanical failure of the irradiated materials. Recent experiments showed that nanovoids in nanotwinned copper could act as sinks for radiation-induced Frank loops, significantly mitigating radiation damage [Y. Chen et al., Nat. Commun. 6:7036 (2015)]. In this paper, we report on structural evolution of Frank loops under cascades and address the role of nanovoids in absorbing Frank loops in detail by using molecular dynamics simulations. Results show that a stand-alone Frank loop is stable under cascades. When Frank loops are adjacentmore » to nanovoids, the diffusion of a group of atoms from the loop into nanovoids is accomplished via the formation and propagation of dislocation loops. The loop-nanovoid interactions result in the shrinkage of the nanovoids and the Frank loops.« less
Nanocluster irradiation evolution in Fe-9%Cr ODS and ferritic-martensitic alloys
NASA Astrophysics Data System (ADS)
Swenson, M. J.; Wharry, J. P.
2017-12-01
The objective of this study is to evaluate the influence of dose rate and cascade morphology on nanocluster evolution in a model Fe-9%Cr oxide dispersion strengthened steel and the commercial ferritic/martensitic (F/M) alloys HCM12A and HT9. We present a large, systematic data set spanning the three alloys, three irradiating particle types, four orders of magnitude in dose rate, and doses ranging 1-100 displacements per atom over 400-500 °C. Nanoclusters are characterized using atom probe tomography. ODS oxide nanoclusters experience partial dissolution after irradiation due to inverse Ostwald ripening, while F/M nanoclusters undergo Ostwald ripening. Damage cascade morphology is indicative of nanocluster number density evolution. Finally, the effects of dose rate on nanocluster morphology provide evidence for a temperature dilation theory, which purports that a negative temperature shift is necessary for higher dose rate irradiations to emulate nanocluster evolution in lower dose rate irradiations.
Status and ecological effects of the world's largest carnivores.
Ripple, William J; Estes, James A; Beschta, Robert L; Wilmers, Christopher C; Ritchie, Euan G; Hebblewhite, Mark; Berger, Joel; Elmhagen, Bodil; Letnic, Mike; Nelson, Michael P; Schmitz, Oswald J; Smith, Douglas W; Wallach, Arian D; Wirsing, Aaron J
2014-01-10
Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large carnivores have substantial effects on the structure and function of diverse ecosystems. Significant cascading trophic interactions, mediated by their prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems. Unexpected effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage. Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth's largest carnivores and all that depends upon them, including humans.
NASA Astrophysics Data System (ADS)
Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.
2013-06-01
The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.
Anisotropic flow and flow fluctuations for Au + Au at √sNN =200 GeV in a multiphase transport model
NASA Astrophysics Data System (ADS)
Ma, L.; Ma, G. L.; Ma, Y. G.
2014-04-01
Anisotropic flow coefficients and their fluctuations are investigated for Au + Au collisions at center-of-mass energy √sNN = 200 GeV by using a multiphase transport model with string melting scenario. Experimental results of azimuthal anisotropies by means of the two- and four-particle cumulants are generally well reproduced by the model including both parton cascade and hadronic rescatterings. Event-by-event treatments of the harmonic flow coefficients vn (for n =2, 3, and 4) are performed, in which event distributions of vn for different orders are consistent with Gaussian shapes over all centrality bins. Systematic studies on centrality, transverse momentum (pT), and pseudorapidity (η) dependencies of anisotropic flows and quantitative estimations of the flow fluctuations are presented. The pT and η dependencies of absolute fluctuations for both v2 and v3 follow trends similar to their flow coefficients. Relative fluctuation of triangular flow v3 is slightly centrality dependent, which is quite different from that of elliptic flow v2. It is observed that parton cascade has a large effect on the flow fluctuations, but hadronic scatterings make little contribution to the flow fluctuations, which indicates flow fluctuations are mainly modified during partonic evolution stage.
NASA Astrophysics Data System (ADS)
Shinde, R. B.; Mali, K. D.
2018-04-01
Collapsible impact energy absorbers play an important role of protecting automotive components from damage during collision. Collision of the two objects results into the damage to one or both of them. Damage may be in the form of crack, fracture and scratch. Designers must know about how the material and object behave under impact event. Owing to above reasons different types of collapsible impact energy absorbers are developed. In the past different studies were undertaken to improve such collapsible impact energy absorbers. This article highlights such studies on common shapes of collapsible impact energy absorber and their impact behaviour under the axial compression. The literature based on studies and analyses of effects of different geometrical parameters on the crushing behaviour of impact energy absorbers is presented in detail. The energy absorber can be of different shape such as circular tube, square tube, and frustums of cone and pyramids. The crushing behaviour of energy absorbers includes studies on crushing mechanics, modes of deformation, energy absorbing capacity, effect on peak and mean crushing load. In this work efforts are made to cover major outcomes from past studies on such behavioural parameters. Even though the major literature reviewed is related to metallic energy absorbers, emphasis is also laid on covering literature on use of composite tube, fiber metal lamination (FML) member, honeycomb plate and functionally graded thickness (FGT) tube as a collapsible impact energy absorber.
Statement of Facts for 1977 City-Wide Mock Trial Competitions. Walker Thomas v. Sam Nomad.
ERIC Educational Resources Information Center
National Inst. for Citizen Education in the Law, Washington, DC.
Prepared by the District of Columbia Street Law Project for its annual city-wide mock trial competition, this instructional handout provides material for a civil case over an automobile accident. Walker Thomas is suing Sam Nomad for damages that resulted from a collision, for which both parties blame the other. The handout clarifies the laws and…
NASA Astrophysics Data System (ADS)
Béland, Laurent Karim; Mousseau, Normand
2012-02-01
The kinetic activation relaxation technique (kinetic ART) method, an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search,ootnotetextL. K. B'eland, P. Brommer, F. El-Mellouhi, J.-F. Joly and N. Mousseau, Phys. Rev. E 84, 046704 (2011). is used to study the relaxation of c-Si after Si^- bombardment at 3 keV. We describe the evolution of the damaged areas at room-temperature and above for periods of the order of seconds, treating long-range elastic deformations exactly. We assess the stability of the nanoscale structures formed by the damage cascade and the mechanisms that govern post-implantation annealing.
Muntifering, Brittany; Blair, Sarah Jane; Gong, Cajer; ...
2015-12-30
Enhanced radiation tolerance of nanostructured metals is attributed to the high density of interfaces that can absorb radiation-induced defects. Here, cavity evolution mechanisms during cascade damage, helium implantation, and annealing of nanocrystalline nickel are characterized via in situ transmission electron microscopy (TEM). Films subjected to self-ion irradiation followed by helium implantation developed evenly distributed cavity structures, whereas films exposed in the reversed order developed cavities preferentially distributed along grain boundaries. Post-irradiation annealing and orientation mapping demonstrated uniform cavity growth in the nanocrystalline structure, and cavities spanning multiple grains. Furthermore, these mechanisms suggest limited ability to reduce swelling, despite the stabilitymore » of the nanostructure.« less
Effects of electronic excitation in 150 keV Ni ion irradiation of metallic systems
NASA Astrophysics Data System (ADS)
Zarkadoula, Eva; Samolyuk, German; Weber, William J.
2018-01-01
We use the two-temperature model in molecular dynamic simulations of 150 keV Ni ion cascades in nickel and nickel-based alloys to investigate the effect of the energy exchange between the atomic and the electronic systems during the primary stages of radiation damage. We find that the electron-phonon interactions result in a smaller amount of defects and affect the cluster formation, resulting in smaller clusters. These results indicate that ignoring the local heating due to the electrons results in the overestimation of the amount of damage and the size of the defect clusters. A comparison of the average defect production to the Norgett-Robinson-Torrens (NRT) prediction over a range of energies is provided.
Collisional Processing of Olivine and Pyroxene in Cometary Dust
NASA Technical Reports Server (NTRS)
Lederer, S. M.; Cintala, M. J.; Olney, R. D.; Keller, L. P.; Nakamura-Messenger, K.; Zolensky, M.
2008-01-01
According to the nebular theory of solar-system formation, collisions between bodies occurred frequently early in the solar system s history and continue at a lower rate even today. Collisions have reworked the surface compositions and structures of cometary nuclei, though to an unknown degree. The majority of the collisional history of a typical Jupiter-family comet takes place while it resides in the Kuiper Belt. Impacts occur on the surfaces of small bodies over a large range of velocities by impactors of all sizes, but typical encounter speeds within the Kuiper Belt are 1.5 to 2.0 km/s[1]. Durda and Stern suggest that the interiors of most cometary nuclei with diameters <5 km have been heavily damaged by collisions [2]. They estimate that over a period of 3.5 Gy, a nucleus with a diameter of 2 km and an orbit between 35-45 AU will experience 90-300 collisions with objects greater than 8 m in diameter. In this same time interval, collisions between a typical Trans-Neptunian Object (TNO) 200 km in diameter and objects with d > 8 m would rework up to one-third of that TNO s surface. In fact, it has been proposed that most short-period comets from the Kuiper Belt (90%) are collisional fragments from larger TNOs - not primordial objects themselves [3] - and that most short-period comets from the Kuiper Belt will be collisionally processed both on their surfaces as well as in their interiors.
Contribution of inflammatory pathways to Fabry disease pathogenesis.
Rozenfeld, Paula; Feriozzi, Sandro
2017-11-01
Lysosomal storage diseases are usually considered to be pathologies in which the passive deposition of unwanted materials leads to functional changes in lysosomes. Lysosomal deposition of unmetabolized glycolipid substrates stimulates the activation of pathogenic cascades, including immunological processes, and particularly the activation of inflammation. In lysosomal storage diseases, the inflammatory response is continuously being activated because the stimulus cannot be eliminated. Consequently, inflammation becomes a chronic process. Lysosomes play a role in many steps of the immune response. Leukocyte perturbation and over-expression of immune molecules have been reported in Fabry disease. Innate immunity is activated by signals originating from dendritic cells via interactions between toll-like receptors and globotriaosylceramide (Gb3) and/or globotriaosylsphingosine (lyso-Gb3). Evidence indicates that these glycolipids can activate toll-like receptors, thus triggering inflammation and fibrosis cascades. In the kidney, Gb3 deposition is associated with the increased release of transforming growth factor beta and with epithelial-to-mesenchymal cell transition, leading to the over-expression of pro-fibrotic molecules and to renal fibrosis. Interstitial fibrosis is also a typical feature of heart involvement in Fabry disease. Endomyocardial biopsies show infiltration of lymphocytes and macrophages, suggesting a role for inflammation in causing tissue damage. Inflammation is present in all tissues and may be associated with other potentially pathologic processes such as apoptosis, impaired autophagy, and increases in pro-oxidative molecules, which could all contribute synergistically to tissue damage. In Fabry disease, the activation of chronic inflammation over time leads to organ damage. Therefore, enzyme replacement therapy must be started early, before this process becomes irreversible. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.
Wang, Wei; Huang, Xuan; Xin, Hong-Bo; Fu, Mingui; Xue, Aimin; Wu, Zhao-Hui
2015-01-01
DNA damage-induced NF-κB activation plays a critical role in regulating cellular response to genotoxic stress. However, the molecular mechanisms controlling the magnitude and duration of this genotoxic NF-κB signaling cascade are poorly understood. We recently demonstrated that genotoxic NF-κB activation is regulated by reversible ubiquitination of several essential mediators involved in this signaling pathway. Here we show that TRAF family member-associated NF-κB activator (TANK) negatively regulates NF-κB activation by DNA damage via inhibiting ubiquitination of TRAF6. Despite the lack of a deubiquitination enzyme domain, TANK has been shown to negatively regulate the ubiquitination of TRAF proteins. We found TANK formed a complex with MCPIP1 (also known as ZC3H12A) and a deubiquitinase, USP10, which was essential for the USP10-dependent deubiquitination of TRAF6 and the resolution of genotoxic NF-κB activation upon DNA damage. Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated deletion of TANK in human cells significantly enhanced NF-κB activation by genotoxic treatment, resulting in enhanced cell survival and increased inflammatory cytokine production. Furthermore, we found that the TANK-MCPIP1-USP10 complex also decreased TRAF6 ubiquitination in cells treated with IL-1β or LPS. In accordance, depletion of USP10 enhanced NF-κB activation induced by IL-1β or LPS. Collectively, our data demonstrate that TANK serves as an important negative regulator of NF-κB signaling cascades induced by genotoxic stress and IL-1R/Toll-like receptor stimulation in a manner dependent on MCPIP1/USP10-mediated TRAF6 deubiquitination. PMID:25861989
SPH simulations of high-speed collisions
NASA Astrophysics Data System (ADS)
Rozehnal, Jakub; Broz, Miroslav
2016-10-01
Our work is devoted to a comparison of: i) asteroid-asteroid collisions occurring at lower velocities (about 5 km/s in the Main Belt), and ii) mutual collisions of asteroids and cometary nuclei usually occurring at significantly higher relative velocities (> 10 km/s).We focus on differences in the propagation of the shock wave, ejection of the fragments and possible differences in the resultingsize-frequency distributions of synthetic asteroid families. We also discuss scaling with respect to the "nominal" target diameter D = 100 km, projectile velocity 3-7 km/s, for which a number of simulations were done so far (Durda et al. 2007, Benavidez et al. 2012).In the latter case of asteroid-comet collisions, we simulate the impacts of brittle or pre-damaged impactors onto solid monolithic targets at high velocities, ranging from 10 to 15 km/s. The purpose of this numerical experiment is to better understand impact processes shaping the early Solar System, namely the primordial asteroid belt during during the (late) heavy bombardment (as a continuation of Broz et al. 2013).For all hydrodynamical simulations we use a smoothed-particle hydrodynamics method (SPH), namely the lagrangian SPH3D code (Benz & Asphaug 1994, 1995). The gravitational interactions between fragments (re-accumulation) is simulated with the Pkdgrav tree-code (Richardson et al. 2000).
An adaptive strategy for active debris removal
NASA Astrophysics Data System (ADS)
White, Adam E.; Lewis, Hugh G.
2014-04-01
Many parameters influence the evolution of the near-Earth debris population, including launch, solar, explosion and mitigation activities, as well as other future uncertainties such as advances in space technology or changes in social and economic drivers that effect the utilisation of space activities. These factors lead to uncertainty in the long-term debris population. This uncertainty makes it difficult to identify potential remediation strategies, involving active debris removal (ADR), that will perform effectively in all possible future cases. Strategies that cannot perform effectively, because of this uncertainty, risk either not achieving their intended purpose, or becoming a hindrance to the efforts of spacecraft manufactures and operators to address the challenges posed by space debris. One method to tackle this uncertainty is to create a strategy that can adapt and respond to the space debris population. This work explores the concept of an adaptive strategy, in terms of the number of objects required to be removed by ADR, to prevent the low Earth orbit (LEO) debris population from growing in size. This was demonstrated by utilising the University of Southampton’s Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) tool to investigate ADR rates (number of removals per year) that change over time in response to the current space environment, with the requirement of achieving zero growth of the LEO population. DAMAGE was used to generate multiple Monte Carlo projections of the future LEO debris environment. Within each future projection, the debris removal rate was derived at five-year intervals, by a new statistical debris evolutionary model called the Computational Adaptive Strategy to Control Accurately the Debris Environment (CASCADE) model. CASCADE predicted the long-term evolution of the current DAMAGE population with a variety of different ADR rates in order to identify a removal rate that produced a zero net growth for that particular projection after 200 years. The results show that using an adaptive ADR rate generated by CASCADE, alongside good compliance with existing mitigation measures, increases the probability of achieving a constant LEO population of objects greater than 10 cm. This was shown to be 12% greater compared with removing five objects per year, with the additional advantage of requiring only 3.1 removals per year, on average.
NASA Astrophysics Data System (ADS)
Yan, Qiang; Shao, Lin
2017-03-01
Current popular Monte Carlo simulation codes for simulating electron bombardment in solids focus primarily on electron trajectories, instead of electron-induced displacements. Here we report a Monte Carol simulation code, DEEPER (damage creation and particle transport in matter), developed for calculating 3-D distributions of displacements produced by electrons of incident energies up to 900 MeV. Electron elastic scattering is calculated by using full-Mott cross sections for high accuracy, and primary-knock-on-atoms (PKAs)-induced damage cascades are modeled using ZBL potential. We compare and show large differences in 3-D distributions of displacements and electrons in electron-irradiated Fe. The distributions of total displacements are similar to that of PKAs at low electron energies. But they are substantially different for higher energy electrons due to the shifting of PKA energy spectra towards higher energies. The study is important to evaluate electron-induced radiation damage, for the applications using high flux electron beams to intentionally introduce defects and using an electron analysis beam for microstructural characterization of nuclear materials.
Microglial activation is a pharmacologically specific marker for the neurotoxic amphetamines.
Thomas, David M; Dowgiert, Jennifer; Geddes, Timothy J; Francescutti-Verbeem, Dina; Liu, Xiuli; Kuhn, Donald M
2004-09-09
Neurotoxic amphetamines cause damage to monoamine nerve terminals of the striatum by unknown mechanisms. Microglial activation contributes to the neuronal damage that accompanies injury, disease, and inflammation, but a role for these cells in amphetamine-induced neurotoxicity has received little attention. We show presently that D-methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), D-amphetamine, and p-chloroamphetamine, each of which has been linked to dopamine (DA) or serotonin nerve terminal damage, result in microglial activation in the striatum. The non-neurotoxic amphetamines l-methamphetamine, fenfluramine, and DOI do not have this effect. All drugs that cause microglial activation also increase expression of glial fibrillary acidic protein (GFAP). At a minimum, microglial activation serves as a pharmacologically specific marker for striatal nerve terminal damage resulting only from those amphetamines that exert neurotoxicity. Because microglia are known to produce many of the reactive species (e.g., nitric oxide, superoxide, cytokines) that mediate the neurotoxicity of the amphetamine-class of drugs, their activation could represent an early and essential event in the neurotoxic cascade associated with high-dose amphetamine intoxication.
The role of free radicals in traumatic brain injury.
O'Connell, Karen M; Littleton-Kearney, Marguerite T
2013-07-01
Traumatic brain injury (TBI) is a significant cause of death and disability in both the civilian and the military populations. The primary impact causes initial tissue damage, which initiates biochemical cascades, known as secondary injury, that expand the damage. Free radicals are implicated as major contributors to the secondary injury. Our review of recent rodent and human research reveals the prominent role of the free radicals superoxide anion, nitric oxide, and peroxynitrite in secondary brain injury. Much of our current knowledge is based on rodent studies, and the authors identified a gap in the translation of findings from rodent to human TBI. Rodent models are an effective method for elucidating specific mechanisms of free radical-induced injury at the cellular level in a well-controlled environment. However, human TBI does not occur in a vacuum, and variables controlled in the laboratory may affect the injury progression. Additionally, multiple experimental TBI models are accepted in rodent research, and no one model fully reproduces the heterogeneous injury seen in humans. Free radical levels are measured indirectly in human studies based on assumptions from the findings from rodent studies that use direct free radical measurements. Further study in humans should be directed toward large samples to validate the findings in rodent studies. Data obtained from these studies may lead to more targeted treatment to interrupt the secondary injury cascades.
Thermal responses in a coronal loop maintained by wave heating mechanisms
NASA Astrophysics Data System (ADS)
Matsumoto, Takuma
2018-05-01
A full 3-dimensional compressible magnetohydrodynamic (MHD) simulation is conducted to investigate the thermal responses of a coronal loop to the dynamic dissipation processes of MHD waves. When the foot points of the loop are randomly and continuously forced, the MHD waves become excited and propagate upward. Then, 1-MK temperature corona is produced naturally as the wave energy dissipates. The excited wave packets become non-linear just above the magnetic canopy, and the wave energy cascades into smaller spatial scales. Moreover, collisions between counter-propagating Alfvén wave packets increase the heating rate, resulting in impulsive temperature increases. Our model demonstrates that the heating events in the wave-heated loops can be nanoflare-like in the sense that they are spatially localized and temporally intermittent.
Heil, Martin; Koch, Thomas; Hilpert, Andrea; Fiala, Brigitte; Boland, Wilhelm; Linsenmair, K. Eduard
2001-01-01
Plant species in at least 66 families produce extrafloral nectar (EFN) on their leaves or shoots and therewith attract predators and parasitoids, such as ants and wasps, which in turn defend them against herbivores. We investigated whether EFN secretion is induced by herbivory and/or artificial damage, and thus can be regarded as an induced defensive response. In addition, we studied the underlying signaling pathway. EFN secretion by field-grown Macaranga tanarius increased after herbivory, artificial leaf damage, and exogenous jasmonic acid (JA) application. Artificial damage strongly enhanced endogenous JA concentrations. The response in EFN production to artificial damage was much less pronounced in those leaves that were treated with phenidone to inhibit endogenous JA synthesis. Quantitative dose–response relations were found between the increase in nectar production and both the intensity of leaf damage and the amounts of exogenously applied JA. The amount of endogenously produced JA was positively correlated with the intensity of leaf damage. Increased numbers of defending insects and decreased numbers of herbivores were observed on leaves after inducing EFN production by exogenous JA treatment. Over 6 weeks, repeatedly applied JA or artificial damage resulted in a ten-fold reduction in herbivory. These results demonstrate that EFN production represents an alternative mechanism for induced, indirect defensive plant responses that are mediated via the octadecanoid signal transduction cascade. PMID:11158598
Active space debris removal—A preliminary mission analysis and design
NASA Astrophysics Data System (ADS)
Castronuovo, Marco M.
2011-11-01
The active removal of five to ten large objects per year from the low Earth orbit (LEO) region is the only way to prevent the debris collisions from cascading. Among the three orbital regions near the Earth where most catastrophic collisions are predicted to occur, the one corresponding to a sun-synchronous condition is considered the most relevant. Forty-one large rocket bodies orbiting in this belt have been identified as the priority targets for removal. As part of a more comprehensive system engineering solution, a space mission dedicated to the de-orbiting of five rocket bodies per year from this orbital regime has been designed. The selected concept of operations envisages the launch of a satellite carrying a number of de-orbiting devices, such as solid propellant kits. The satellite performs a rendezvous with an identified object and mates with it by means of a robotic arm. A de-orbiting device is attached to the object by means of a second robotic arm, the object is released and the device is activated. The spacecraft travels then to the next target. The present paper shows that an active debris removal mission capable of de-orbiting 35 large objects in 7 years is technically feasible, and the resulting propellant mass budget is compatible with many existing platforms.
Aad, G.; Abbott, B.; Abdallah, J.; ...
2011-10-21
An inclusive search is presented for new physics in events with two isolated leptons (e or μ) having the same electric charge. The data are selected from events collected from pp collisions at √s = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb –1. The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sourcesmore » of same-sign high-mass dilepton events in the ee, eμ and μμ channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. In conclusion, a lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks.« less
NASA Astrophysics Data System (ADS)
Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Alam, M. S.; Alam, M. A.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Andeen, T.; Anders, C. F.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonelli, S.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Bella, L. Aperio; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Aubert, B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Baltasar Dos Santos Pedrosa, F.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, D.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Battistoni, G.; Bauer, F.; Bawa, H. S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Harpaz, S. Behar; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ben Ami, S.; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blazek, T.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bona, M.; Bondarenko, V. G.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brown, H.; Brubaker, E.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.; Buchanan, J.; Buchanan, N. J.; Buchholz, P.; Buckingham, R. M.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Budick, B.; Büscher, V.; Bugge, L.; Buira-Clark, D.; Bulekov, O.; Bunse, M.; Buran, T.; Burckhart, H.; Burdin, S.; Burgess, T.; Burke, S.; Busato, E.; Bussey, P.; Buszello, C. P.; Butin, F.; Butler, B.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Buttinger, W.; Byatt, T.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Caloi, R.; Calvet, D.; Calvet, S.; Camacho Toro, R.; Camard, A.; Camarri, P.; Cambiaghi, M.; Cameron, D.; Cammin, J.; Campana, S.; Campanelli, M.; Canale, V.; Canelli, F.; Canepa, A.; Cantero, J.; Capasso, L.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capriotti, D.; Capua, M.; Caputo, R.; Caramarcu, C.; Cardarelli, R.; Carli, T.; Carlino, G.; Carminati, L.; Caron, B.; Caron, S.; Carrillo Montoya, G. D.; Carter, A. A.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Cascella, M.; Caso, C.; Castaneda Hernandez, A. M.; Castaneda-Miranda, E.; Castillo Gimenez, V.; Castro, N. F.; Cataldi, G.; Cataneo, F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Cattani, G.; Caughron, S.; Cauz, D.; Cavalleri, P.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Cazzato, A.; Ceradini, F.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cetin, S. A.; Cevenini, F.; Chafaq, A.; Chakraborty, D.; Chan, K.; Chapleau, B.; Chapman, J. D.; Chapman, J. W.; Chareyre, E.; Charlton, D. G.; Chavda, V.; Cheatham, S.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, L.; Chen, S.; Chen, T.; Chen, X.; Cheng, S.; Cheplakov, A.; Chepurnov, V. 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B.; Ferencei, J.; Ferland, J.; Fernando, W.; Ferrag, S.; Ferrando, J.; Ferrara, V.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferrer, A.; Ferrer, M. L.; Ferrere, D.; Ferretti, C.; Ferretto Parodi, A.; Fiascaris, M.; Fiedler, F.; Filipčič, A.; Filippas, A.; Filthaut, F.; Fincke-Keeler, M.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, G.; Fischer, P.; Fisher, M. J.; Fisher, S. M.; Flacco, C. J.; Flechl, M.; Fleck, I.; Fleckner, J.; Fleischmann, P.; Fleischmann, S.; Flick, T.; Flores Castillo, L. R.; Flowerdew, M. J.; Föhlisch, F.; Fokitis, M.; Fonseca Martin, T.; Forbush, D. A.; Formica, A.; Forti, A.; Fortin, D.; Foster, J. M.; Fournier, D.; Foussat, A.; Fowler, A. J.; Fowler, K.; Fox, H.; Francavilla, P.; Franchino, S.; Francis, D.; Frank, T.; Franklin, M.; Franz, S.; Fraternali, M.; Fratina, S.; French, S. T.; Froeschl, R.; Froidevaux, D.; Frost, J. 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E.; Taylor, G. N.; Taylor, W.; Teixeira Dias Castanheira, M.; Teixeira-Dias, P.; Temming, K. K.; Ten Kate, H.; Teng, P. K.; Terada, S.; Terashi, K.; Terron, J.; Terwort, M.; Testa, M.; Teuscher, R. J.; Thadome, J.; Therhaag, J.; Theveneaux-Pelzer, T.; Thioye, M.; Thoma, S.; Thomas, J. P.; Thompson, E. N.; Thompson, P. D.; Thompson, P. D.; Thompson, A. S.; Thomson, E.; Thomson, M.; Thun, R. P.; Tic, T.; Tikhomirov, V. O.; Tikhonov, Y. A.; Timmermans, C. J. W. P.; Tipton, P.; Tique Aires Viegas, F. J.; Tisserant, S.; Tobias, J.; Toczek, B.; Todorov, T.; Todorova-Nova, S.; Toggerson, B.; Tojo, J.; Tokár, S.; Tokunaga, K.; Tokushuku, K.; Tollefson, K.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, G.; Tonoyan, A.; Topfel, C.; Topilin, N. D.; Torchiani, I.; Torrence, E.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Traynor, D.; Trefzger, T.; Treis, J.; Tremblet, L.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Trinh, T. N.; Tripiana, M. F.; Trischuk, W.; Trivedi, A.; Trocmé, B.; Troncon, C.; Trottier-McDonald, M.; Trzupek, A.; Tsarouchas, C.; Tseng, J. C.-L.; Tsiakiris, M.; Tsiareshka, P. V.; Tsionou, D.; Tsipolitis, G.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsukerman, I. I.; Tsulaia, V.; Tsung, J.-W.; Tsuno, S.; Tsybychev, D.; Tua, A.; Tuggle, J. M.; Turala, M.; Turecek, D.; Turk Cakir, I.; Turlay, E.; Turra, R.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Tyrvainen, H.; Tzanakos, G.; Uchida, K.; Ueda, I.; Ueno, R.; Ugland, M.; Uhlenbrock, M.; Uhrmacher, M.; Ukegawa, F.; Unal, G.; Underwood, D. G.; Undrus, A.; Unel, G.; Unno, Y.; Urbaniec, D.; Urkovsky, E.; Urrejola, P.; Usai, G.; Uslenghi, M.; Vacavant, L.; Vacek, V.; Vachon, B.; Vahsen, S.; Valenta, J.; Valente, P.; Valentinetti, S.; Valkar, S.; Valladolid Gallego, E.; Vallecorsa, S.; Valls Ferrer, J. A.; van der Graaf, H.; van der Kraaij, E.; Van Der Leeuw, R.; van der Poel, E.; van der Ster, D.; Van Eijk, B.; van Eldik, N.; van Gemmeren, P.; van Kesteren, Z.; van Vulpen, I.; Vandelli, W.; Vandoni, G.; Vaniachine, A.; Vankov, P.; Vannucci, F.; Varela Rodriguez, F.; Vari, R.; Varnes, E. W.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vassilakopoulos, V. I.; Vazeille, F.; Vegni, G.; Veillet, J. J.; Vellidis, C.; Veloso, F.; Veness, R.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Vichou, I.; Vickey, T.; Viehhauser, G. H. A.; Viel, S.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinek, E.; Vinogradov, V. B.; Virchaux, M.; Viret, S.; Virzi, J.; Vitale, A.; Vitells, O.; Viti, M.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vlasak, M.; Vlasov, N.; Vogel, A.; Vokac, P.; Volpi, G.; Volpi, M.; Volpini, G.; von der Schmitt, H.; von Loeben, J.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobiev, A. P.; Vorwerk, V.; Vos, M.; Voss, R.; Voss, T. T.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vu Anh, T.; Vuillermet, R.; Vukotic, I.; Wagner, W.; Wagner, P.; Wahlen, H.; Wakabayashi, J.; Walbersloh, J.; Walch, S.; Walder, J.; Walker, R.; Walkowiak, W.; Wall, R.; Waller, P.; Wang, C.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, J. C.; Wang, R.; Wang, S. M.; Warburton, A.; Ward, C. P.; Warsinsky, M.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, A. T.; Waugh, B. M.; Weber, J.; Weber, M.; Weber, M. S.; Weber, P.; Weidberg, A. R.; Weigell, P.; Weingarten, J.; Weiser, C.; Wellenstein, H.; Wells, P. S.; Wen, M.; Wenaus, T.; Wendler, S.; Weng, Z.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Werth, M.; Wessels, M.; Weydert, C.; Whalen, K.; Wheeler-Ellis, S. J.; Whitaker, S. P.; White, A.; White, M. J.; White, S.; Whitehead, S. R.; Whiteson, D.; Whittington, D.; Wicek, F.; Wicke, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiik, L. A. M.; Wijeratne, P. A.; Wildauer, A.; Wildt, M. A.; Wilhelm, I.; Wilkens, H. G.; Will, J. Z.; Williams, E.; Williams, H. H.; Willis, W.; Willocq, S.; Wilson, J. A.; Wilson, M. G.; Wilson, A.; Wingerter-Seez, I.; Winkelmann, S.; Winklmeier, F.; Wittgen, M.; Wolter, M. W.; Wolters, H.; Wooden, G.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wraight, K.; Wright, C.; Wrona, B.; Wu, S. L.; Wu, X.; Wu, Y.; Wulf, E.; Wunstorf, R.; Wynne, B. M.; Xaplanteris, L.; Xella, S.; Xie, S.; Xie, Y.; Xu, C.; Xu, D.; Xu, G.; Yabsley, B.; Yamada, M.; Yamamoto, A.; Yamamoto, K.; Yamamoto, S.; Yamamura, T.; Yamaoka, J.; Yamazaki, T.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, U. K.; Yang, Y.; Yang, Y.; Yang, Z.; Yanush, S.; Yao, W.-M.; Yao, Y.; Yasu, Y.; Ybeles Smit, G. V.; Ye, J.; Ye, S.; Yilmaz, M.; Yoosoofmiya, R.; Yorita, K.; Yoshida, R.; Young, C.; Youssef, S.; Yu, D.; Yu, J.; Yu, J.; Yuan, L.; Yurkewicz, A.; Zaets, V. G.; Zaidan, R.; Zaitsev, A. M.; Zajacova, Z.; Zalite, Yo. K.; Zanello, L.; Zarzhitsky, P.; Zaytsev, A.; Zeitnitz, C.; Zeller, M.; Zemla, A.; Zendler, C.; Zenin, A. V.; Zenin, O.; Ženiš, T.; Zenonos, Z.; Zenz, S.; Zerwas, D.; Zevi della Porta, G.; Zhan, Z.; Zhang, D.; Zhang, H.; Zhang, J.; Zhang, X.; Zhang, Z.; Zhao, L.; Zhao, T.; Zhao, Z.; Zhemchugov, A.; Zheng, S.; Zhong, J.; Zhou, B.; Zhou, N.; Zhou, Y.; Zhu, C. G.; Zhu, H.; Zhu, Y.; Zhuang, X.; Zhuravlov, V.; Zieminska, D.; Zimmermann, R.; Zimmermann, S.; Zimmermann, S.; Ziolkowski, M.; Zitoun, R.; Zivković, L.; Zmouchko, V. V.; Zobernig, G.; Zoccoli, A.; Zolnierowski, Y.; Zsenei, A.; zur Nedden, M.; Zutshi, V.; Zwalinski, L.
2011-10-01
An inclusive search is presented for new physics in events with two isolated leptons ( e or μ) having the same electric charge. The data are selected from events collected from pp collisions at sqrt {s} = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb-1. The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, eμ and μμ channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks.
Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; ...
2012-11-16
A study of dijet production in proton-proton collisions was performed at sqrt(s) = 7 TeV for jets with pt > 35 GeV and abs(y) < 4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as 'inclusive'. Events with exactly one pair of jets are called 'exclusive'. The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity difference between jets abs(Delta(y)) is measured for the first time up to abs(Delta(y)) = 9.2. Themore » ratio of the cross section for the pair consisting of the most forward and the most backward jet from the inclusive sample to the exclusive dijet cross section is also presented. The predictions of the Monte Carlo event generators PYTHIA6 and PYTHIA8 agree with the measurements. In both ratios the HERWIG++ generator exhibits a more pronounced rise versus abs(Delta(y)) than observed in the data. The BFKL-motivated generators CASCADE and HEJ+ARIADNE predict for these ratios a significantly stronger rise than observed.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.
A study of dijet production in proton-proton collisions was performed at sqrt(s) = 7 TeV for jets with pt > 35 GeV and abs(y) < 4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as 'inclusive'. Events with exactly one pair of jets are called 'exclusive'. The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity difference between jets abs(Delta(y)) is measured for the first time up to abs(Delta(y)) = 9.2. Themore » ratio of the cross section for the pair consisting of the most forward and the most backward jet from the inclusive sample to the exclusive dijet cross section is also presented. The predictions of the Monte Carlo event generators PYTHIA6 and PYTHIA8 agree with the measurements. In both ratios the HERWIG++ generator exhibits a more pronounced rise versus abs(Delta(y)) than observed in the data. The BFKL-motivated generators CASCADE and HEJ+ARIADNE predict for these ratios a significantly stronger rise than observed.« less
NASA Astrophysics Data System (ADS)
Gann, V. V.; Tolstolutskaya, G. D.
2008-08-01
An experimental study confirms the possibility of nuclear fusion reactions initiating in metal-deuterium targets by bombarding them with ions that are not the reagents of the fusion reaction, in particular, with noble gas ions. The yields of (d,d) and (d,t) reactions were measured as functions of energy (0.4-3.2 MeV) and mass of incident ions (He +, Ne +, Ar +, Kr + and Xe +). Irradiation by heavy ions produced a number of energetic deuterium atoms in the deuteride and deuterium + tritium metal targets. At ion energies of ˜0.1-1 MeV the d-d reaction yields are relatively high. A model of nuclear fusion reaction cross-sections in atomic collision cascades initiated by noble gas ion beam in metal-deuterium target is developed. The method for calculation tritium or deuterium recoil fluxes and the yield of d-d fusion reaction in subsequent collisions was proposed. It was shown that D(d,p)t and D(t,n) 4He reactions mainly occur in energy region of the recoiled D-atom from 10 keV to 250 keV. The calculated probabilities of d-d and d-t fusion reactions were found to be in a good agreement with the experimental data.
Fracture Strength of Fused Silica From Photonic Signatures Around Collision Sites
NASA Technical Reports Server (NTRS)
Yost, William T.; Cramer, K Elliott
2015-01-01
Impact sites in glass affect its fracture strength. An analytical model that predicts fracture strength from grey-field polariscope (GFP) readings (photoelastic retardations) has been developed and reported in the literature. The model is suggestive that stress fields, resulting from impact damage, destablizes sites within the glass, which lead to pathways that cause strength degradation. Using data collected from fused silica specimens fabricated from outer window panes that were designed for the space shuttle, the model was tested against four categories of inflicted damage. The damage sites were cored from the window carcasses, examined with the GFP and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and the photoelastic retardation measured at the damage site in each specimen. A least-squares fit is calculated. The results are compared with the predictions from the model. A plausible single-sided NDE damage site inspection method (a version of which is planned for glass inspection in the Orion Project) that relates photoelastic retardation in glass components to its fracture strength is presented.
The influence of neutron radiation damage on the optical properties of plastic scintillator UPS 923A
NASA Astrophysics Data System (ADS)
Mthembu, Skhathisomusa; Davydov, Yuri; Baranov, Vladimir; Mellado Garcia, Bruce; Mdhluli, Joyful; Sideras-Haddad, Elias
2017-09-01
Plastic scintillators are vital in the reconstruction of hadronic particle energy and tracks resulting from the collision of high energy particles in the Large Hadron Collider (LHC) at CERN. These plastic scintillators are exposed to harsh radiation environments and are susceptible to radiation damage. The effects of radiation damage on the transmittance, luminescence and light yield of Ukraine polystyrene-based scintillator UPS 923A were studied. Samples were irradiated with fast neutrons, of varying energies and fluences, using the IBR-2 reactor FLNP (Frank Laboratory for Nuclear Problems) at the Joint Institute for Nuclear Research. Results show a small change in the transmittance of the higher energy visible spectrum, and a noticeable change in the light yield of the samples as a result of the damage. There is no change observed on the luminescence as a result of radiation damage at studied fluences. The doses and uences of the neutrons shall be increased and changes in optical properties as a result of the radiation shall be further studied.
NASA Astrophysics Data System (ADS)
Yun, Jinsik; Ha, Dong Sam; Inman, Daniel J.; Owen, Robert B.
2011-03-01
Structural damage for spacecraft is mainly due to impacts such as collision of meteorites or space debris. We present a structural health monitoring (SHM) system for space applications, named Adverse Event Detection (AED), which integrates an acoustic sensor, an impedance-based SHM system, and a Lamb wave SHM system. With these three health-monitoring methods in place, we can determine the presence, location, and severity of damage. An acoustic sensor continuously monitors acoustic events, while the impedance-based and Lamb wave SHM systems are in sleep mode. If an acoustic sensor detects an impact, it activates the impedance-based SHM. The impedance-based system determines if the impact incurred damage. When damage is detected, it activates the Lamb wave SHM system to determine the severity and location of the damage. Further, since an acoustic sensor dissipates much less power than the two SHM systems and the two systems are activated only when there is an acoustic event, our system reduces overall power dissipation significantly. Our prototype system demonstrates the feasibility of the proposed concept.
NASA Astrophysics Data System (ADS)
Jones, N.; Wierzbicki, T.
The application of solid, structural, and experimental mechanics to predict the crumpling behavior and energy absorption of thin-walled structures under quasi-static compression and various dynamic crash loadings is examined in reviews of current research. Both fundamental aspects and specific problems in the design of crashworthy aircraft, automobiles, railroad cars, ships, and offshore installations are considered. Topics discussed include laterally compressed metal tubes as impact-energy absorbers, crushing behavior of plate intersections, axial crushing of fiber-reinforced composite tubes, finite-element analysis of structural crashworthiness in the automotive and aerospace industries, crash behavior of aircraft fuselage structures, aircraft crash analysis, ship collisions, and structural damage in airship and rolling-stock collisions. Photographs, graphs, drawings, and diagrams are provided.
Radiation effects in accelerator components
NASA Astrophysics Data System (ADS)
Borden, M. J.
1995-05-01
A review of basic radiation effects is presented. The fundamental definitions of radioactivity are given for alpha, beta, positron decay, gamma-ray emission and electron capture. The interaction of neutrons with material is covered including: absorption through radiative capture, neutron-proton interaction, alpha particle emission, neutron-multi-neutron reactions and fission. Basic equations defining inelastic and elastic scattering are presented with examples of neutron energy loss per collision for several elements. Photon interactions are considered for gamma-rays and x-rays. Photoelectric collisions, the Compton effect and pair production are reviewed. Electron-proton interactions are discussed with emphasis placed on defect production. Basic displacement damage mechanisms for photon and particle interaction are presented. Several examples of radiation effects to plastics, electronics and ceramics are presented. Extended references are given for each example.
The fast debris evolution model
NASA Astrophysics Data System (ADS)
Lewis, H. G.; Swinerd, G. G.; Newland, R. J.; Saunders, A.
2009-09-01
The 'particles-in-a-box' (PIB) model introduced by Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] removed the need for computer-intensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FADE), employs a first-order differential equation to describe the rate at which new objects ⩾10 cm are added and removed from the environment. Whilst Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FADE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FADE model has been implemented as a client-side, web-based service using JavaScript embedded within a HTML document. Due to the simple nature of the algorithm, FADE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ⩾10 cm LEO debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model. The results demonstrate that the FADE model is able to capture comparable time-series of collisions and number of objects as predicted by DAMAGE in several scenarios. Further, and perhaps more importantly, its speed and flexibility allows the user to explore and understand the evolution of the space debris environment.
NASA Technical Reports Server (NTRS)
Levin, George M.; Christiansen, Eric L.
1997-01-01
The pre-flight predictions and postflight assessments carried out in relation to a series of Space Shuttle missions are reviewed, and data are presented for the meteoroid and orbital debris damage observed on the Hubble Space Telescope during the 1994 Hubble repair mission. Pre-flight collision risk analyses are carried out prior to each mission, and in the case of an unacceptable risk, the mission profile is altered until the risk is considered to be acceptable. The NASA's BUMPER code is used to compute the probability of damage from debris and meteoroid particle impacts based on the Poisson statistical model for random events. The penetration probability calculation requires information concerning the geometry of the critical systems, the penetration resistance and mission profile parameters. Following each flight, the orbiter is inspected for meteoroid and space debris damage. The emphasis is on areas such as the radiator panels, the windows and the reinforced carbon-carbon structures on the leading wing edges and on the nose cap. The contents of damage craters are analyzed using a scanning electron microscope to determine the nature and origin of the impactor. Hypervelocity impact tests are often performed to simulate the observed damage and to estimate the nature of the damaging particles. The number and type of damage observed provides information concerning the orbital debris environment.