Forecasting scenarios of collision catastrophes produced by celestial body falls

Science.gov (United States)

Shor, V.; Kochetova, O.; Chernetenko, Y.; Zheleznov, N.; Deryugin, V.; Zaitsev, A.

2014-07-01

The subject under discussion arose in the course of developing a computer program, which gives the possibility for numerical and graphical modeling of the scenarios of catastrophes caused by collisions of cosmic bodies with the Earth. It is expected that this program can be used for computer-assisted training of the personnel of units of the Ministry for Emergency Situations in the case of a situation caused by the fall of a celestial body on the Earth. Also, it is anticipated that the program can be used in real situations when a dangerous body is discovered on an orbit leading to an imminent collision with the Earth. From the scientific point of view, both variants of use require solving of analogous tasks. In what follows, we discuss both variants. 1. The computation of the circumstances for a fall on the Earth (or approach within short distance) of a real body begins with the determination of its orbit from the observations available using the least-squares method. The mean square error of the representation of the observations on the base of the initial values of the coordinates and the velocities is computed, as well as their covariance matrix. Then, the trajectory of the body's motion is followed by numerical integration starting from the osculating epoch to the collision with the Earth or to its flyby. The computer program takes into account the various cases: at the initial moment, the body can move away from or approach the Earth, it can be outside the sphere of action or inside it. At the moment, when the body enters the sphere of action, the coordinates of the center of the dispersion ellipse on the target plane are computed as well as the dimensions of its axes. Using these data, the probability of collision with the Earth is calculated. Then, the point of penetration of the body into the Earth's atmosphere at a given height above the level of the Earth geoid is determined. In case the body is passing by the Earth, the minimum distance of the body from

Stochastic orbital migration of small bodies in Saturn's rings

Science.gov (United States)

Rein, H.; Papaloizou, J. C. B.

2010-12-01

Many small moonlets that create propeller structures have been found in Saturn's rings by the Cassini spacecraft. We study the dynamical evolution of such 20-50 m sized bodies, which are embedded in Saturn's rings. We estimate the importance of various interaction processes with the ring particles on the moonlet's eccentricity and semi-major axis analytically. For low ring surface densities, the main effects on the evolution of the eccentricity and the semi-major axis are found to be caused by collisions and the gravitational interaction with particles in the vicinity of the moonlet. For high surface densities, the gravitational interaction with self-gravity wakes becomes important. We also perform realistic three-dimensional, collisional N-body simulations with up to a quarter of a million particles. A new set of pseudo shear periodic boundary conditions is used, which reduces the computational costs by an order of magnitude compared to previous studies. Our analytic estimates are confirmed to within a factor of two. On short timescales the evolution is always dominated by stochastic effects caused by collisions and gravitational interaction with self-gravitating ring particles. These result in a random walk of the moonlet's semi-major axis. The eccentricity of the moonlet quickly reaches an equilibrium value owing to collisional damping. The average change in semi-major axis of the moonlet after 100 orbital periods is 10-100m. This translates to an offset in the azimuthal direction of several hundred kilometres. We expect that such a shift is easily observable. Two movies are only available in electronic form at http://www.aanda.org

Model of the humanoid body for self collision detection based on elliptical capsules

CSIR Research Space (South Africa)

Dube, C

2011-12-01

Full Text Available . The humanoid body is modeled using elliptical capsules, while the moving segments, i.e. arms and legs, of the humanoid are modeled using circular capsules. This collision detection model provides a good fit to the humanoid body shape while being simple...

Collision recognition and direction changes for small scale fish robots by acceleration sensors

Science.gov (United States)

Na, Seung Y.; Shin, Daejung; Kim, Jin Y.; Lee, Bae-Ho

2005-05-01

Typical obstacles are walls, rocks, water plants and other nearby robots for a group of small scale fish robots and submersibles that have been constructed in our lab. Sonar sensors are not employed to make the robot structure simple enough. All of circuits, sensors and processor cards are contained in a box of 9 x 7 x 4 cm dimension except motors, fins and external covers. Therefore, image processing results are applied to avoid collisions. However, it is useful only when the obstacles are located far enough to give images processing time for detecting them. Otherwise, acceleration sensors are used to detect collision immediately after it happens. Two of 2-axes acceleration sensors are employed to measure the three components of collision angles, collision magnitudes, and the angles of robot propulsion. These data are integrated to calculate the amount of propulsion direction change. The angle of a collision incident upon an obstacle is the fundamental value to obtain a direction change needed to design a following path. But there is a significant amount of noise due to a caudal fin motor. Because caudal fin provides the main propulsion for a fish robot, there is a periodic swinging noise at the head of a robot. This noise provides a random acceleration effect on the measured acceleration data at the collision. We propose an algorithm which shows that the MEMS-type accelerometers are very effective to provide information for direction changes in spite of the intrinsic noise after the small scale fish robots have made obstacle collision.

COLLISIONS BETWEEN GRAVITY-DOMINATED BODIES. II. THE DIVERSITY OF IMPACT OUTCOMES DURING THE END STAGE OF PLANET FORMATION

International Nuclear Information System (INIS)

Stewart, Sarah T.; Leinhardt, Zoë M.

2012-01-01

Numerical simulations of the stochastic end stage of planet formation typically begin with a population of embryos and planetesimals that grow into planets by merging. We analyzed the impact parameters of collisions leading to the growth of terrestrial planets from recent N-body simulations that assumed perfect merging and calculated more realistic outcomes using a new analytic collision physics model. We find that collision outcomes are diverse and span all possible regimes: hit-and-run, merging, partial accretion, partial erosion, and catastrophic disruption. The primary outcomes of giant impacts between planetary embryos are approximately evenly split between partial accretion, graze-and-merge, and hit-and-run events. To explore the cumulative effects of more realistic collision outcomes, we modeled the growth of individual planets with a Monte Carlo technique using the distribution of impact parameters from N-body simulations. We find that fewer planets reached masses >0.7 M Earth using the collision physics model compared to simulations that assumed every collision results in perfect merging. For final planets with masses >0.7 M Earth , 60% are enriched in their core-to-mantle mass fraction by >10% compared to the initial embryo composition. Fragmentation during planet formation produces significant debris (∼15% of the final mass) and occurs primarily by erosion of the smaller body in partial accretion and hit-and-run events. In partial accretion events, the target body grows by preferentially accreting the iron core of the projectile and the escaping fragments are derived primarily from the silicate mantles of both bodies. Thus, the bulk composition of a planet can evolve via stochastic giant impacts.

A comprehensive analysis of small-passerine fatalities from collision with turbines at wind energy facilities.

Directory of Open Access Journals (Sweden)

Wallace P Erickson

Full Text Available Small passerines, sometimes referred to as perching birds or songbirds, are the most abundant bird group in the United States (US and Canada, and the most common among bird fatalities caused by collision with turbines at wind energy facilities. We used data compiled from 116 studies conducted in the US and Canada to estimate the annual rate of small-bird fatalities. It was necessary for us to calculate estimates of small-bird fatality rates from reported all-bird rates for 30% of studies. The remaining 70% of studies provided data on small-bird fatalities. We then adjusted estimates to account for detection bias and loss of carcasses from scavenging. These studies represented about 15% of current operating capacity (megawatts [MW] for all wind energy facilities in the US and Canada and provided information on 4,975 bird fatalities, of which we estimated 62.5% were small passerines comprising 156 species. For all wind energy facilities currently in operation, we estimated that about 134,000 to 230,000 small-passerine fatalities from collision with wind turbines occur annually, or 2.10 to 3.35 small birds/MW of installed capacity. When adjusted for species composition, this indicates that about 368,000 fatalities for all bird species are caused annually by collisions with wind turbines. Other human-related sources of bird deaths, (e.g., communication towers, buildings [including windows], and domestic cats have been estimated to kill millions to billions of birds each year. Compared to continent-wide population estimates, the cumulative mortality rate per year by species was highest for black-throated blue warbler and tree swallow; 0.043% of the entire population of each species was estimated to annually suffer mortality from collisions with turbines. For the eighteen species with the next highest values, this estimate ranged from 0.008% to 0.038%, much lower than rates attributed to collisions with communication towers (1.2% to 9.0% for top

A comprehensive analysis of small-passerine fatalities from collision with turbines at wind energy facilities.

Science.gov (United States)

Erickson, Wallace P; Wolfe, Melissa M; Bay, Kimberly J; Johnson, Douglas H; Gehring, Joelle L

2014-01-01

Small passerines, sometimes referred to as perching birds or songbirds, are the most abundant bird group in the United States (US) and Canada, and the most common among bird fatalities caused by collision with turbines at wind energy facilities. We used data compiled from 116 studies conducted in the US and Canada to estimate the annual rate of small-bird fatalities. It was necessary for us to calculate estimates of small-bird fatality rates from reported all-bird rates for 30% of studies. The remaining 70% of studies provided data on small-bird fatalities. We then adjusted estimates to account for detection bias and loss of carcasses from scavenging. These studies represented about 15% of current operating capacity (megawatts [MW]) for all wind energy facilities in the US and Canada and provided information on 4,975 bird fatalities, of which we estimated 62.5% were small passerines comprising 156 species. For all wind energy facilities currently in operation, we estimated that about 134,000 to 230,000 small-passerine fatalities from collision with wind turbines occur annually, or 2.10 to 3.35 small birds/MW of installed capacity. When adjusted for species composition, this indicates that about 368,000 fatalities for all bird species are caused annually by collisions with wind turbines. Other human-related sources of bird deaths, (e.g., communication towers, buildings [including windows]), and domestic cats) have been estimated to kill millions to billions of birds each year. Compared to continent-wide population estimates, the cumulative mortality rate per year by species was highest for black-throated blue warbler and tree swallow; 0.043% of the entire population of each species was estimated to annually suffer mortality from collisions with turbines. For the eighteen species with the next highest values, this estimate ranged from 0.008% to 0.038%, much lower than rates attributed to collisions with communication towers (1.2% to 9.0% for top twenty species).

A comprehensive analysis of small-passerine fatalities from collisions with turbines at wind energy facilities

Science.gov (United States)

Erickson, Wallace P.; Wolfe, Melissa M.; Bay, Kimberly J.; Johnson, Douglas H.; Gehring, Joelle L.

2014-01-01

Small passerines, sometimes referred to as perching birds or songbirds, are the most abundant bird group in the United States (US) and Canada, and the most common among bird fatalities caused by collision with turbines at wind energy facilities. We used data compiled from 39 studies conducted in the US and Canada to estimate the annual rate of small-bird fatalities. It was necessary for us to calculate estimates of small-bird fatality rates from reported all-bird rates for 30% of studies. The remaining 70% of studies provided data on small-bird fatalities. We then adjusted estimates to account for detection bias and loss of carcasses from scavenging. These studies represented about 15% of current operating capacity (megawatts [MW]) for all wind energy facilities in the US and Canada and provided information on 4,975 bird fatalities, of which we estimated 62.5% were small passerines comprising 156 species. For all wind energy facilities currently in operation, we estimated that about 134,000 to 230,000 small-passerine fatalities from collision with wind turbines occur annually, or 2.10 to 3.35 small birds/MW of installed capacity. When adjusted for species composition, this indicates that about 368,000 fatalities for all bird species are caused annually by collisions with wind turbines. Other human-related sources of bird deaths, (e.g., communication towers, buildings [including windows]), and domestic cats) have been estimated to kill millions to billions of birds each year. Compared to continent-wide population estimates, the cumulative mortality rate per year by species was highest for black-throated blue warbler and tree swallow; 0.043% of the entire population of each species was estimated to annually suffer mortality from collisions with turbines. For the eighteen species with the next highest values, this estimate ranged from 0.008% to 0.038%, much lower than rates attributed to collisions with communication towers (1.2% to 9.0% for top twenty species).

The scattering matrix element of the three body reactive collision

International Nuclear Information System (INIS)

Morsy, M.W.; Hilal, A.A.; El-Sabagh, M.A.

1980-08-01

The optical model approximation has been applied to a previously derived set of coupled equations representing the dynamics of the three-body reactive scattering. The Schroedinger equation obtained describing the scattering problem has then been solved by inserting the effective mass approximation. The asymptotic requirements for both the entrance and exit channels, respectively, have been supplied to give the scattering matrix element of the reactive collision. (author)

A particle-in-cell method for modeling small angle Coulomb collisions in plasmas

International Nuclear Information System (INIS)

Parker, S.E.

1989-01-01

We propose a computational method to self-consistently model small angle collisional effects. This method may be added to standard Particle-In-Cell (PIC) plasma simulations to include collisions, or as an alternative to solving the Fokker-Planck (FP) equation using finite difference methods. The distribution function is represented by a large number of particles. The particle velocities change due to the drag force, and the diffusion in velocity is represented by a random process. This is similar to previous Monte-Carlo methods except we calculate the drag force and diffusion tensor self- consistently. The particles are weighted to a grid in velocity space and associated ''Poisson equations'' are solved for the Rosenbluth potentials. The motivation is to avoid the very time consuming method of Coulomb scattering pair by pair. First the approximation for small angle Coulomb collisions is discussed. Next, the FP-PIC collision method is outlined. Then we show a test of the particle advance modeling an electron beam scattering off a fixed ion background. 4 refs

Spin State Estimation of Tumbling Small Bodies

Science.gov (United States)

Olson, Corwin; Russell, Ryan P.; Bhaskaran, Shyam

2016-06-01

It is expected that a non-trivial percentage of small bodies that future missions may visit are in non-principal axis rotation (i.e. "tumbling"). The primary contribution of this paper is the application of the Extended Kalman Filter (EKF) Simultaneous Localization and Mapping (SLAM) method to estimate the small body spin state, mass, and moments of inertia; the spacecraft position and velocity; and the surface landmark locations. The method uses optical landmark measurements, and an example scenario based on the Rosetta mission is used. The SLAM method proves effective, with order of magnitude decreases in the spacecraft and small body spin state errors after less than a quarter of the comet characterization phase. The SLAM method converges nicely for initial small body angular velocity errors several times larger than the true rates (effectively having no a priori knowledge of the angular velocity). Surface landmark generation and identification are not treated in this work, but significant errors in the initial body-fixed landmark positions are effectively estimated. The algorithm remains effective for a range of different truth spin states, masses, and center of mass offsets that correspond to expected tumbling small bodies throughout the solar system.

Simulations of collisions between N-body classical systems in interaction; Simulations de collisions entre systemes classiques a n-corps en interaction

Energy Technology Data Exchange (ETDEWEB)

Morisseau, Francois [Laboratoire de Physique Corpusculaire de CAEN, ENSICAEN, Universite de Caen Basse-Normandie, UFR des Sciences, 6 bd Marechal Juin, 14050 Caen Cedex (France)

2006-05-15

The Classical N-body Dynamics (CNBD) is dedicated to the simulation of collisions between classical systems. The 2-body interaction used here has the properties of the Van der Waals potential and depends on just a few parameters. This work has two main goals. First, some theoretical approaches assume that the dynamical stage of the collisions plays an important role. Moreover, colliding nuclei are supposed to present a 1. order liquid-gas phase transition. Several signals have been introduced to show this transition. We have searched for two of them: the bimodality of the mass asymmetry and negative heat capacity. We have found them and we give an explanation of their presence in our calculations. Second, we have improved the interaction by adding a Coulomb like potential and by taking into account the stronger proton-neutron interaction in nuclei. Then we have figured out the relations that exist between the parameters of the 2-body interaction and the properties of the systems. These studies allow us to fit the properties of the classical systems to those of the nuclei. In this manuscript the first results of this fit are shown. (author)

One dimensional two-body collisions experiment based on LabVIEW interface with Arduino

Science.gov (United States)

Saphet, Parinya; Tong-on, Anusorn; Thepnurat, Meechai

2017-09-01

The purpose of this work is to build a physics lab apparatus that is modern, low-cost and simple. In one dimensional two-body collisions experiment, we used the Arduino UNO R3 as a data acquisition system which was controlled by LabVIEW program. The photogate sensors were designed using LED and LDR to measure position as a function of the time. Aluminium frame houseware and blower were used for the air track system. In both totally inelastic and elastic collision experiments, the results of momentum and energy conservation are in good agreement with the theoretical calculations.

Cluster-collision frequency. II. Estimation of the collision rate

International Nuclear Information System (INIS)

Amadon, A.S.; Marlow, W.H.

1991-01-01

Gas-phase cluster-collision rates, including effects of cluster morphology and long-range intermolecular forces, are calculated. Identical pairs of icosahedral or dodecahedral carbon tetrachloride clusters of 13, 33, and 55 molecules in two different relative orientations were discussed in the preceding paper [Phys. Rev. A 43, 5483 (1991)]: long-range interaction energies were derived based upon (i) exact calculations of the iterated, or many-body, induced-dipole interaction energies for the clusters in two fixed relative orientations; and (ii) bulk, or continuum descriptions (Lifshitz--van der Waals theory), of spheres of corresponding masses and diameters. In this paper, collision rates are calculated according to an exact description of the rates for small spheres interacting via realistic potentials. Utilizing the interaction energies of the preceding paper, several estimates of the collision rates are given by treating the discrete clusters in fixed relative orientations, by computing rotationally averaged potentials for the discrete clusters, and by approximating the clusters as continuum spheres. For the discrete, highly symmetric clusters treated here, the rates using the rotationally averaged potentials closely approximate the fixed-orientation rates and the values of the intercluster potentials for cluster surface separations under 2 A have negligible effect on the overall collision rates. While the 13-molecule cluster-collision rate differs by 50% from the rate calculated as if the cluster were bulk matter, the two larger cluster-collision rates differ by less than 15% from the macroscopic rates, thereby indicating the transition of microscopic to macroscopic behavior

Electron capture in proton collisions with alkali atoms as a three-body problem

International Nuclear Information System (INIS)

Avakov, G.V.; Blokhintsev, L.D.; Kadyrov, A.S.; Mukhamedzhanov, A.M.

1992-01-01

A previous paper proposed an approach to the calculation of electron transfer reactions in ion-atomic collisions based on the Faddeev three-body equations written in the Alt-Grassberger-Sandhas form. In the present work this approach is used to describe the electron capture in proton collisions with alkali atoms. The results of calculation of the total and partial cross sections for charge exchange in proton collisions with Li, Na, K and Rb atoms are presented. The calculated total cross sections are in good agreement with experiment for light target atoms. In going over to heavier targets, the theoretical total cross sections, while agreeing in form, tend to be larger than the experimental ones. The calculated partial cross sections for electron capture into the 2s state of the H atom are also in agreement with experiment. Some other partial cross sections were also calculated. (author)

Multiplicity distributions in small phase-space domains in central nucleus-nucleus collisions

International Nuclear Information System (INIS)

Baechler, J.; Hoffmann, M.; Runge, K.; Schmoetten, E.; Bartke, J.; Gladysz, E.; Kowalski, M.; Stefanski, P.; Bialkowska, H.; Bock, R.; Brockmann, R.; Sandoval, A.; Buncic, P.; Ferenc, D.; Kadija, K.; Ljubicic, A. Jr.; Vranic, D.; Chase, S.I.; Harris, J.W.; Odyniec, G.; Pugh, H.G.; Rai, G.; Teitelbaum, L.; Tonse, S.; Derado, I.; Eckardt, V.; Gebauer, H.J.; Rauch, W.; Schmitz, N.; Seyboth, P.; Seyerlein, J.; Vesztergombi, G.; Eschke, J.; Heck, W.; Kabana, S.; Kuehmichel, A.; Lahanas, M.; Lee, Y.; Le Vine, M.; Margetis, S.; Renfordt, R.; Roehrich, D.; Rothard, H.; Schmidt, E.; Schneider, I.; Stock, R.; Stroebele, H.; Wenig, S.; Fleischmann, B.; Fuchs, M.; Gazdzicki, M.; Kosiec, J.; Skrzypczak, E.; Keidel, R.; Piper, A.; Puehlhofer, F.; Nappi, E.; Posa, F.; Paic, G.; Panagiotou, A.D.; Petridis, A.; Vassileiadis, G.; Pfenning, J.; Wosiek, B.

1992-10-01

Multiplicity distributions of negatively charged particles have been studied in restricted phase space intervals for central S + S, O + Au and S + Au collisions at 200 GeV/nucleon. It is shown that multiplicity distributions are well described by a negative binomial form irrespectively of the size and dimensionality of phase space domain. A clan structure analysis reveals interesting similarities between complex nuclear collisions and a simple partonic shower. The lognormal distribution agrees reasonably well with the multiplicity data in large domains, but fails in the case of small intervals. No universal scaling function was found to describe the shape of multiplicity distributions in phase space intervals of varying size. (orig.)

Collision tumor of Small Cell Carcinoma and Squamous Cell Carcinoma of maxillary sinus

Directory of Open Access Journals (Sweden)

Irfan Sugianto

2016-06-01

Full Text Available Two kinds of different malignant tumors occurring within the same organ is defined as collision tumor. Small Cell Carcinoma (SmCC is high-grade derived from neuroendocrine cell tumors, occurance in the head and neck is rare. Squamous Cell Carcinoma (SCC is the most common malignancies encountered in head and neck area, but the occuranceof collision tumor is very rare. This report describe a 82 year-old woman patient with a SmCC and SCC that occurred in the maxillary sinus. CT was performed including with enhancement, MRI examination was T1WI, STIR and contrast enhancement. We also conducted analysis of Dynamic Contrast Enhancement (DCE. Histopathologic examination revealed small cell carcinoma. A distant metastasis was not detected. After patient received chemoradiotherapy (CCRT, most of  tumorwas reduced although a part of the tumor was remained. Pathological examination of surgery tumor specimen revealed that specimen consisted of SCC and SmCC was disappeared, and six months after surgery, the patient suffered tumor recurrence and multiple metastasis to the organs in the abdomen. This time we have to report that the experience one cases that are considered collision cancer of SmCC and SCC that occurred in the maxillary sinus.

High velocity collisions between large dust aggregates at the limit for growing planetesimals

Science.gov (United States)

Wurm, G.; Teiser, J.; Paraskov, G.

2007-08-01

Planetesimals are km-size bodies supposed to be formed in protoplanetary disks as planetary precursors [1]. The most widely considered mechanism for their formation is based on mutual collisions of smaller bodies, a process which starts with the aggregation of (sub)-micron size dust particles. In the absence of events that lithify the growing dust aggregates, only the surface forces between dust particles provide adhesion and internal strength of the objects. It has been assumed that this might be a disadvantage as dust aggregates are readily destroyed by rather weak collisions. In fact, experimental research on dust aggregation showed that for collisions in the m/s range (sub)-mm size dust aggregates impacting a larger body do show a transition from sticking to rebound and/or fragmentation in collisions and no growth occurs at the large velocities [2, 3]. This seemed to be incompatible with typical collision velocities of small dust aggregates with m-size bodies which are expected to be on the order 50 m/s in protoplanetary disks [4]. We recently found that the experimental results cannot be scaled from m/s to tens of m/s collisions. In contrast to the assumptions and somewhat counterintuitive, it is the fragility of dust aggregates that allows growth at higher collision velocities. In impact experiments Wurm et al. [5] showed that between 13 m/s and 25 m/s a larger compact (target) body consisting of micron-size SiO2 dust particles accreted 50 % of the mass of a 1 cm dust projectile consisting of the same dust. For slower impacts the projectile only rebounded or fragmented slightly.

Cratering on Small Bodies: Lessons from Eros

Science.gov (United States)

Chapman, C. R.

2003-01-01

Cratering and regolith processes on small bodies happen continuously as interplanetary debris rains down on asteroids, comets, and planetary satellites. Butthey are very poorly observed and not well understood. On the one hand, we have laboratory experimentation at small scales and we have examination of large impact craters (e.g. Meteor Crater on Earth and imaging of abundant craters on terrestrial planets and outer planet moons). Understanding cratering on bodies of intermediate scales, tens of meters to hundreds of km in size, involves either extrapolation from our understanding of cratering phenomena at very different scales or reliance on very preliminary, incomplete examination of the observational data we now have for a few small bodies. I review the latter information here. It has been generally understood that the role of gravity is greatly diminished for smaller bodies, so a lot of cratering phenomena studied for larger bodies is less applicable. But it would be a mistake to imagine that laboratory experiments on gravitationless rocks (usually at 1 g) are directly applicable, except perhaps to those monolithic Near Earth Asteroids (NEAs) some tens of meters in size that spin very rapidly and can be assumed to be "large bare rocks" with "negative gravity". Whereas it had once been assumed that asteroids smaller than some tens of km diameter would retain little regolith, it is increasingly apparent that regolith and megoregolith processes extend down to bodies only hundreds of meters in size, perhaps smaller. Yet these processes are very different from those that pertain to the Moon, which is our chief prototype of regolith processes. The NEAR Shoemaker spacecraft's studies of Eros provide the best evidence to date about small-body cratering processes, as well as a warning that our theoretical understanding requires anchoring by direct observations. Eros: "Ponds", Paucity of Small Craters, and Other Mysteries. Although Eros is currently largely detached

Small-bodied humans from Palau, Micronesia.

Directory of Open Access Journals (Sweden)

Lee R Berger

Full Text Available UNLABELLED: Newly discovered fossil assemblages of small bodied Homo sapiens from Palau, Micronesia possess characters thought to be taxonomically primitive for the genus Homo. BACKGROUND: Recent surface collection and test excavation in limestone caves in the rock islands of Palau, Micronesia, has produced a sizeable sample of human skeletal remains dating roughly between 940-2890 cal ybp. PRINCIPLE FINDINGS: Preliminary analysis indicates that this material is important for two reasons. First, individuals from the older time horizons are small in body size even relative to "pygmoid" populations from Southeast Asia and Indonesia, and thus may represent a marked case of human insular dwarfism. Second, while possessing a number of derived features that align them with Homo sapiens, the human remains from Palau also exhibit several skeletal traits that are considered to be primitive for the genus Homo. SIGNIFICANCE: These features may be previously unrecognized developmental correlates of small body size and, if so, they may have important implications for interpreting the taxonomic affinities of fossil specimens of Homo.

Nuclear collision theory with many-body correlations, 2

International Nuclear Information System (INIS)

Kurihara, Yukio.

1984-12-01

A nuclear collision theory, in which the many-body correlation induced by the strong short-ranged repulsion and medium-ranged attraction of the realistic NN interaction is explicitly included, is applied to the deuteron+deuteron elastic scattering at low energies. Pair correlation functions calculated by the present theory are very different from the Hackenbroich et al. 's one. They contain not only the short-ranged suppressive correlation, but also the medium-ranged enhancing correlation. The former changes the shape of the d-d potential from the wine-bottle one. And the latter makes the d-d potential much more attractive. This effect is necessary for reproducing a bump around thatesub(cm)=90 0 in the experimental elastic differential cross section. The phase shifts evaluated by the present theory are compared with those from the resonating-group method. (author)

Modelling of transport and collisions between rigid bodies to simulate the jam formation in urban flows

Directory of Open Access Journals (Sweden)

S Hadji

2008-09-01

Full Text Available This study deals with the simulation of transport and interaction betweenbodies considered as a rectangular shape particles, in urban flow. We usedan hydrodynamic two-dimensional finite elements model coupled to theparticles model based on Maxey-Riley equations, and taking into accountof contact between bodies. The finite element discretization is based onthe velocity field richer than pressure field, and the particles displacementsare computed by using a rigid body motion method. A collision strategy isalso developed to handle cases in which bodies touch.

Collision Repair Campaign

Science.gov (United States)

The Collision Repair Campaign targets meaningful risk reduction in the Collision Repair source category to reduce air toxic emissions in their communities. The Campaign also helps shops to work towards early compliance with the Auto Body Rule.

The motion of the rigid body in viscous fluid including collisions. Global solvability result

Czech Academy of Sciences Publication Activity Database

Chemetov, N.; Nečasová, Šárka

2017-01-01

Roč. 34, April (2017), s. 416-445 ISSN 1468-1218 R&D Projects: GA ČR GA16-03230S Institutional support: RVO:67985840 Keywords : rigid body * global weak solution * collisions in finite time Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.659, year: 2016 http://www.sciencedirect.com/science/article/pii/S1468121816301146

Asymptotic form of the charge exchange cross section in the three body rearrangement collisions

Science.gov (United States)

Omidvar, K.

1975-01-01

A three body general rearrangement collision is considered where the initial and final bound states are described by the hydrogen-like wave functions. Mathematical models are developed to establish the relationships of quantum number, the reduced mass, and the nuclear charge of the final state. It is shown that for the low lying levels, the reciprocal of n cubed scaling law at all incident energies is only approximately satisfied. The case of the symmetric collisions is considered and it is shown that for high n and high incident energy, E, the cross section behaves as the reciprocal of E cubed. Zeros and minima in the differential cross sections in the limit of high n for protons on atomic hydrogen and positrons on atomic hydrogen are given.

Forward di-jet production in p+Pb collisions in the small-x improved TMD factorization framework

CERN Document Server

van Hameren, A.; Kutak, K.; Marquet, C.; Petreska, E.; Sapeta, S.

2016-01-01

We study the production of forward di-jets in proton-lead and proton-proton collisions at the Large Hadron Collider. Such configurations, with both jets produced in the forward direction, impose a dilute-dense asymmetry which allows to probe the gluon density of the lead or proton target at small longitudinal momentum fractions. Even though the jet momenta are always much bigger than the saturation scale of the target, $Q_s$, the transverse momentum imbalance of the di-jet system may be either also much larger than $Q_s$, or of the order $Q_s$, implying that the small-$x$ QCD dynamics involved is either linear or non-linear, respectively. The small-$x$ improved TMD factorization framework deals with both situation in the same formalism. In the latter case, which corresponds to nearly back-to-back jets, we find that saturation effects induce a significant suppression of the forward di-jet azimuthal correlations in proton-lead versus proton-proton collisions.

Forward di-jet production in p+Pb collisions in the small-x improved TMD factorization framework

Energy Technology Data Exchange (ETDEWEB)

Hameren, A. van [The H. Niewodniczański Institute of Nuclear Physics PAN,Radzikowskiego 152, 31-342 Kraków (Poland); Kotko, P. [Department of Physics, Penn State University,University Park, 16803 PA (United States); Kutak, K. [The H. Niewodniczański Institute of Nuclear Physics PAN,Radzikowskiego 152, 31-342 Kraków (Poland); Marquet, C. [Centre de Physique Théorique, École Polytechnique,CNRS, Université Paris-Saclay,91128 Palaiseau (France); Petreska, E. [Centre de Physique Théorique, École Polytechnique,CNRS, Université Paris-Saclay,91128 Palaiseau (France); Departamento de Física de Partículas and IGFAE,Universidade de Santiago de Compostela,15782 Santiago de Compostela (Spain); Sapeta, S. [Theoretical Physics Department, CERN,Geneva (Switzerland); The H. Niewodniczański Institute of Nuclear Physics PAN,Radzikowskiego 152, 31-342 Kraków (Poland)

2016-12-12

We study the production of forward di-jets in proton-lead and proton-proton collisions at the Large Hadron Collider. Such configurations, with both jets produced in the forward direction, impose a dilute-dense asymmetry which allows to probe the gluon density of the lead or proton target at small longitudinal momentum fractions. Even though the jet momenta are always much bigger than the saturation scale of the target, Q{sub s}, the transverse momentum imbalance of the di-jet system may be either also much larger than Q{sub s}, or of the order Q{sub s}, implying that the small-x QCD dynamics involved is either linear or non-linear, respectively. The small-x improved TMD factorization framework deals with both situations in the same formalism. In the latter case, which corresponds to nearly back-to-back jets, we find that saturation effects induce a significant suppression of the forward di-jet azimuthal correlations in proton-lead versus proton-proton collisions.

Rapidity and multiplicity correlations in high energy hadronic collisions

International Nuclear Information System (INIS)

Heiselberg, H.

1993-01-01

Rapidity and multiplicity correlations of particle production in high energy hadronic collisions are studied. A simple model including short range correlations in rapidity due to clustering and long range correlations due to energy conservation is able to describe the two-body correlation functions well hadron-nucleon collisions around lab energies of 250 GeV. In this model fractional moments are calculated and compared to data. The strong rise of the factorial moments in rapidity intervals by size δy∝1 can be explained by long and short range correlation alone whereas the factorial moments approach a constant value at very small δy due to lack of correlations also in agreement with experiment. There is therefore no need for introducing intermittency in the particle production in hadronic collisions at these energies. (orig.)

Quantum control of quasi-collision states: A protocol for hybrid fusion

Science.gov (United States)

Vilela Mendes, R.

2018-04-01

When confined to small regions quantum systems exhibit electronic and structural properties different from their free space behavior. These properties are of interest, for example, for molecular insertion, hydrogen storage and the exploration of new pathways for chemical and nuclear reactions. Here, a confined three-body problem is studied, with emphasis on the study of the “quantum scars” associated to dynamical collisions. For the particular case of nuclear reactions, it is proposed that a molecular cage might simply be used as a confining device with the collision states accessed by quantum control techniques.

Topological regularizations of the triple collision singularity in the 3-vortex problem

International Nuclear Information System (INIS)

Hiraoka, Yasuaki

2008-01-01

The triple collision singularity in the 3-vortex problem is studied in this paper. Under the necessary condition k 1 -1 +k 2 -1 +k 3 -1 =0 for vorticities to have the triple collision, the main results are summarized as follows: (i) For k 1 = k 2 , the triple collision singularity is topologically regularizable. (ii) For 0 1 − k 2 | < ε with a sufficiently small ε, the triple collision singularity is not topologically regularizable. First of all, in order to prove these statements, all singularities in the 3-vortex problem are classified. Then, we introduce a dynamical system by blowing up the triple collision singularity with an appropriate time scaling. Roughly speaking, it corresponds to pasting an invariant manifold at the triple collision singularity on the original phase space. This technique is well known as McGehee's collision manifold (1974 Inventions Math. 27 191–227) in the N-body problem of celestial mechanics. Finally, by adopting the viewpoint of Easton (1971 J. Diff. Eqns 10 92–9), topological regularizations of the triple collision singularity are studied in detail

Innershell ionisation at small impactparameters in proton-atom collisions

International Nuclear Information System (INIS)

Duinker, W.

1981-01-01

This thesis concentrates on innershell ionisation in proton-atom collisions. An experiment on K-shell ionisation of argon is described, performed in a gasfilled collision chamber under single collision conditions. Further experiments with carbon and aluminium were performed, the K-shell vacancy production in the collision of protons with these atoms being detected through the measurement of Auger-electrons. A spectrometer with a large solid angle was specially constructed for this and its performance is described. K-shell ionisation accompanying nuclear (p,γ) reactions has also been measured using 26 Mg and 27 Al. (Auth./C.F.)

How to combine binary collision approximation and multi-body potential for molecular dynamics

International Nuclear Information System (INIS)

Saito, Seiki; Nakamura, Hiroaki; Takayama, Arimichi; Ito, Atsushi M.; Kenmotsu, Takahiro

2010-01-01

Our group has been developing a hybrid simulation of the molecular dynamics (MD) and the binary collision approximation (BCA) simulation. One of the main problems of this hybridization model is that the multi-body potential suddenly appears at the moment when the simulation method switches from the BCA to the MD. This instantaneously emerged multi-body potential causes the acceleration or deceleration of atoms of the system. To solve this problem, the kinetic energy of atoms should be corrected to conserve the total energy in the system. This paper gives the solution. The hybrid simulation for hydrogen atom injection into a graphite material is executed in order to demonstrate the solution. (author)

A Big Year for Small Bodies

Science.gov (United States)

Mayo, Louis; Erickson, K.

2013-10-01

2013 is a watershed year for celestial events involving the solar system’s unsung heroes, small bodies. The Cosmic Valentine of Asteroid 2012 DA14 which passed within ~ 3.5 Earth radii of the Earth's surface (February 15, 2013), Comet C/2011 L4 PANSTARRS and the Thanksgiving 2013 pass of Comet ISON, which will pass less than 0.012 AU (1.8 million km) from the solar surface and could be visible during the day. All this in addition to Comet Lemmon and a host of meteor showers makes 2013 a landmark year to deliver the excitement of planetary science to the audiences worldwide. To deliver the excitement and wonder of our solar system’s small bodies to worldwide audiences, NASA’s JPL and GSFC education teams in partnership with NASA EDGE will reach out to the public through multiple venues including broadcast media, social media, science and math focused educational activities, observing challenges, interactive visualization tools like “Eyes on the Solar System” and more culminating in the Thanksgiving Day Comet ISON perihelion passage. This talk will highlight NASA’s focused education effort to engage the public in small bodies science and the role these objects play in our understanding of the formation and evolution of the solar system.

SU-E-T-106: Development of a Collision Prediction Algorithm for Determining Problematic Geometry for SBRT Treatments Using a Stereotactic Body Frame

Energy Technology Data Exchange (ETDEWEB)

Wagar, M; Friesen, S; Mannarino, E [Dana-Farber/Brigham and Women' s Cancer Center, Boston, MA (United States); Hacker, F [Dana-Farber/Brigham and Women' s Cancer Center, Boston, MA (United States); Harvard Medical School, Boston, MA (United States)

2014-06-01

Purpose: Collision between the gantry and the couch or patient during Radiotherapy is not a common concern for conventional RT (static fields or arc). With the increase in the application of stereotactic planning techniques to the body, collisions have become a greater concern. Non-coplanar beam geometry is desirable in stereotatic treatments in order to achieve sharp gradients and a high conformality. Non-coplanar geometry is less intuitive in the body and often requires an iterative process of planning and dry runs to guarantee deliverability. Methods: Purpose written software was developed in order to predict the likelihood of collision between the head of the gantry and the couch, patient or stereotatic body frame. Using the DICOM plan and structures set, exported by the treatment planning system, this software is able to predict the possibility of a collision. Given the plan's isocenter, treatment geometry and exterior contours, the software is able to determine if a particular beam/arc is clinically deliverable or if collision is imminent. Results: The software was tested on real world treatment plans with untreatable beam geometry. Both static non-coplanar and VMAT plans were tested. Of these, the collision prediction software could identify all as having potentially problematic geometry. Re-plans of the same cases were also tested and validated as deliverable. Conclusion: This software is capable of giving good initial indication of deliverability for treatment plans that utilize complex geometry (SBRT) or have lateral isocenters. This software is not intended to replace the standard pre-treatment QA dry run. The effectiveness is limited to those portions of the patient and immobilization devices that have been included in the simulation CT and contoured in the planning system. It will however aid the planner in reducing the iterations required to create complex treatment geometries necessary to achieve ideal conformality and organ sparing.

Flyby Characterization of Lower-Degree Spherical Harmonics Around Small Bodies

Science.gov (United States)

Takahashi, Yu; Broschart, Stephen; Lantoine, Gregory

2014-01-01

Interest in studying small bodies has grown significantly in the last two decades, and there are a number of past, present, and future missions. These small body missions challenge navigators with significantly different kinds of problems than the planets and moons do. The small bodies' shape is often irregular and their gravitational field significantly weak, which make the designing of a stable orbit a complex dynamical problem. In the initial phase of spacecraft rendezvous with a small body, the determination of the gravitational parameter and lower-degree spherical harmonics are of crucial importance for safe navigation purposes. This motivates studying how well one can determine the total mass and lower-degree spherical harmonics in a relatively short time in the initial phase of the spacecraft rendezvous via flybys. A quick turnaround for the gravity data is of high value since it will facilitate the subsequent mission design of the main scientific observation campaign. We will present how one can approach the problem to determine a desirable flyby geometry for a general small body. We will work in the non-dimensional formulation since it will generalize our results across different size/mass bodies and the rotation rate for a specific combination of gravitational coefficients.

Collision group and renormalization of the Boltzmann collision integral

Science.gov (United States)

Saveliev, V. L.; Nanbu, K.

2002-05-01

On the basis of a recently discovered collision group [V. L. Saveliev, in Rarefied Gas Dynamics: 22nd International Symposium, edited by T. J. Bartel and M. Gallis, AIP Conf. Proc. No. 585 (AIP, Melville, NY, 2001), p. 101], the Boltzmann collision integral is exactly rewritten in two parts. The first part describes the scattering of particles with small angles. In this part the infinity due to the infinite cross sections is extracted from the Boltzmann collision integral. Moreover, the Boltzmann collision integral is represented as a divergence of the flow in velocity space. Owing to this, the role of collisions in the kinetic equation can be interpreted in terms of the nonlocal friction force that depends on the distribution function.

Small Body Exploration Technologies as Precursors for Interstellar Robotics

Energy Technology Data Exchange (ETDEWEB)

Noble, Robert; /SLAC; Sykes, Mark V.; /PSI, Tucson

2012-02-15

The scientific activities undertaken to explore our Solar System will be the same as required someday at other stars. The systematic exploration of primitive small bodies throughout our Solar System requires new technologies for autonomous robotic spacecraft. These diverse celestial bodies contain clues to the early stages of the Solar System's evolution as well as information about the origin and transport of water-rich and organic material, the essential building blocks for life. They will be among the first objects studied at distant star systems. The technologies developed to address small body and outer planet exploration will form much of the technical basis for designing interstellar robotic explorers. The Small Bodies Assessment Group, which reports to NASA, initiated a Technology Forum in 2011 that brought together scientists and technologists to discuss the needs and opportunities for small body robotic exploration in the Solar System. Presentations and discussions occurred in the areas of mission and spacecraft design, electric power, propulsion, avionics, communications, autonomous navigation, remote sensing and surface instruments, sampling, intelligent event recognition, and command and sequencing software. In this paper, the major technology themes from the Technology Forum are reviewed, and suggestions are made for developments that will have the largest impact on realizing autonomous robotic vehicles capable of exploring other star systems.

Towards relativistic heavy ion collisions 'by small steps towards the stars'

International Nuclear Information System (INIS)

Scott, D.K.

1980-01-01

Current attempts to search for the exotic processes occurring in relativistic heavy ion collisions are reviewed under the headings; peripheral collisions (peripheral collisions as a function of energy, new features at intermediate energies, ground state correlations, microscopic aspects), central collisions (low energy perspective, time scales in heavy ion collisions, spatial, temporal localization and the onset of the nuclear fireball, models of particle emission in central relativistic collisions, the heart of the matter, multiplicity selection, the emission of composite particles), a search for the exotic (the limits of temperature and pressure, temporal and spatial limits, the limits of nuclear matter and nuclei,). 229 references. (U.K.)

Application of the Faddeev-Watson expansion to thermal collisions of Rydberg atoms with neutral particles

International Nuclear Information System (INIS)

de Prunele, E.

1983-01-01

The Faddeev-Watson expansion (FWE) for the T operator is applied to the study of thermal collisions between Rydberg atom and neutral atom. These collisions are considered as a three-body problem (the perturber, the Rydberg electron, and its parent core) and it is assumed, as already done in most theoretical works dealing with Rydberg-atom--atom collisions, that the core-perturber interaction can be neglected. Then the evaluation of the FWE first- and second-order terms is made tractable by using an appropriate separable potential for the Rydberg-electron--perturber interaction. The evaluation of the second-order term allows us to estimate the importance of taking into account explicitly the Rydberg-electron--core interaction in the expression of the (three-body) T operator for the thermal collisions considered. Detailed calculations for the process Rb(n, l = 0)+He →Rb(n',l')+He are presented and discussed. The FWE second-order term has been evaluated for the first time by taking the (two-body) t operator associated with the Rydberg atom (valence electron plus parent core) as the Coulomb potential. The contribution of the FWE second-order term to the scattering amplitude decreases as n increases and is found especially significant when both the momentum transfers involved in the collision are large and the values of l and l' are small

Small angle Ar2+ + Ar collisions

International Nuclear Information System (INIS)

Stevens, J.J.

1983-01-01

Electron capture in Ar 2+ + Ar is studied at low keV energies. Using Ar 2+ + He collisions as a calibration, it is shown that the dominant single electron capture process is endothermic and of the type Ar 2+ ( 3 P) + Ar → Ar + ( 2 P) + Ar + (3s 2 3p 4 nI), with nI primarily being 3d and 4p. Weaker exothermic processes are also found and are due mainly to the existence of long-lived highly-excited states in the incident Ar 2+ beam. The direct scattering and double electron capture processes are also studied. Direct scattering occurs with no target excitation. Differential cross sections are presented for the collision processes. The single electron capture results are interpreted using a simple model in which a strongly attractive intermediate state couples with incident and outgoing channels

Ratios of strange hadrons to pions in collisions of large and small nuclei

Energy Technology Data Exchange (ETDEWEB)

Oeschler, H. [Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Cleymans, J. [University of Cape Town, UCT-CERN Research Centre and Department of Physics, Rondebosch (South Africa); Hippolyte, B. [Universite de Strasbourg, CNRS-IN2P3, Institut Pluridisciplinaire Hubert Curien (IPHC), Strasbourg (France); Redlich, K. [University of Wroclaw, Institute of Theoretical Physics, Wroclaw (Poland); ExtreMe Matter Institute EMMI, GSI, Darmstadt (Germany); Sharma, N. [Panjab University, Department of Physics, Chandigarh (India)

2017-09-15

The dependence of particle production on the size of the colliding nuclei is analyzed in terms of the thermal model using the canonical ensemble. The concept of strangeness correlation in clusters of sub-volume V{sub c} is used to account for the suppression of strangeness. A systematic analysis is presented of the predictions of the thermal model for particle production in collisions of small nuclei. The pattern of the maxima of strange-particles-to-pion ratios as a function of beam energy is quite special, as they do not occur at the same beam energy and are sensitive to the system size. In particular, the Λ/π{sup +} ratio shows a clear maximum even for small systems while the maximum in the K{sup +}/π{sup +} ratio is less pronounced in small systems. (orig.)

Towards relativistic heavy ion collisions by small steps towards the stars

International Nuclear Information System (INIS)

Scott, D.K.

1979-03-01

A review lecture is given on current attempts to search for the exotic processes occurring in relativistic heavy ion collisions. From peripheral collisions the discussion proceeds to central collisions and lastly the search for the exotic, in which the tools developed for the study of peripheral and central collisions are used. 200 references

Effects of phase memory in spectroscopy of test field of two level system at small frequencies of collisions

International Nuclear Information System (INIS)

Parkhomenko, A.I.; Shalagin, A.M.

2006-01-01

One studied theoretically spectrum of absorption (intensification) of a weak sounding field by two-level atoms moving in a strong resonance laser field and colliding with buffer gas atoms. The analysis was performed for the case of small frequencies of collisions in contrast to the Doppler width of absorption line (gas low pressure) with regard to the arbitrary variation of a radiation induced dipole moment phase at elastic collisions of gas particles. The effects of phase memory are found to result in very strong quantitative and qualitative transformation of a test field spectrum even in case of infrequent collisions when the well-known Dike mechanism of manifestation of phase memory effects (elimination of the Doppler widening due to limitation of spatial motion of particles by collisions) does not work. Strong influence of phase memory effects on spectral resonances at gas low pressure results from the fact that phase retaining collisions change dependence on velocity of the partial index of refraction n(v) (index of refraction for particles moving with v velocity) [ru

Nonlinear gravitational self-force: Field outside a small body

Science.gov (United States)

Pound, Adam

2012-10-01

A small extended body moving through an external spacetime gαβ creates a metric perturbation hαβ, which forces the body away from geodesic motion in gαβ. The foundations of this effect, called the gravitational self-force, are now well established, but concrete results have mostly been limited to linear order. Accurately modeling the dynamics of compact binaries requires proceeding to nonlinear orders. To that end, I show how to obtain the metric perturbation outside the body at all orders in a class of generalized wave gauges. In a small buffer region surrounding the body, the form of the perturbation can be found analytically as an expansion for small distances r from a representative worldline. Given only a specification of the body’s multipole moments, the field obtained in the buffer region suffices to find the metric everywhere outside the body via a numerical puncture scheme. Following this procedure at first and second order, I calculate the field in the buffer region around an arbitrarily structured compact body at sufficiently high order in r to numerically implement a second-order puncture scheme, including effects of the body’s spin. I also define nth-order (local) generalizations of the Detweiler-Whiting singular and regular fields and show that in a certain sense, the body can be viewed as a skeleton of multipole moments.

Proton-proton correlations at small relative momentum in neon and argon collision with nuclei at Saturne

International Nuclear Information System (INIS)

Alard, J.P.; Dupieux, P.; Charmensat, P.; Augerat, J.; Babinet, R.; Cavaton, C.; Demoulins, M.; Lemaire, M.C.; Brochard, F.; Gorodetzky, P.; Racca, C.

1990-01-01

Proton proton correlations at small relative momentum have been studied using the Diogene 4π- Facility at Saturne. The incident energies vary from 200 to 1000 A.MeV for Ne and Ar projectiles on various targets. Experimental correlation functions are compared to theoretical calculations of S. Koonin, corrected for experimental biases. This paper gives the values of the source size as a function of incident energy, target-projectile system and centrality of the collisions. Extracted values of eh density of nuclear matter show that the method is mainly sensitive to the final stage of the interaction; nevertheless we have some indications of a highly compressed phase at the beginning collision

Quasi-four-body treatment of charge transfer in the collision of protons with atomic helium: I. Thomas related mechanisms

Science.gov (United States)

Safarzade, Zohre; Fathi, Reza; Shojaei Akbarabadi, Farideh; Bolorizadeh, Mohammad A.

2018-04-01

The scattering of a completely bare ion by atoms larger than hydrogen is at least a four-body interaction, and the charge transfer channel involves a two-step process. Amongst the two-step interactions of the high-velocity single charge transfer in an anion-atom collision, there is one whose amplitude demonstrates a peak in the angular distribution of the cross sections. This peak, the so-called Thomas peak, was predicted by Thomas in a two-step interaction, classically, which could also be described through three-body quantum mechanical models. This work discusses a four-body quantum treatment of the charge transfer in ion-atom collisions, where two-step interactions illustrating a Thomas peak are emphasized. In addition, the Pauli exclusion principle is taken into account for the initial and final states as well as the operators. It will be demonstrated that there is a momentum condition for each two-step interaction to occur in a single charge transfer channel, where new classical interactions lead to the Thomas mechanism.

Dynamical evolution of small bodies in the Solar System

Science.gov (United States)

Jacobson, Seth A.

2012-05-01

This thesis explores the dynamical evolution of small bodies in the Solar System. It focuses on the asteroid population but parts of the theory can be applied to other systems such as comets or Kuiper Belt objects. Small is a relative term that refers to bodies whose dynamics can be significantly perturbed by non-gravitational forces and tidal torques on timescales less than their lifetimes (for instance the collisional timescale in the Main Belt asteroid population or the sun impact timescale for the near-Earth asteroid population). Non-gravitational torques such as the YORP effect can result in the active endogenous evolution of asteroid systems; something that was not considered more than twenty years ago. This thesis is divided into three independent studies. The first explores the dynamics of a binary systems immediately after formation from rotational fission. The rotational fission hypothesis states that a rotationally torqued asteroid will fission when the centrifugal accelerations across the body exceed gravitational attraction. Asteroids must have very little or no tensile strength for this to occur, and are often referred to as "rubble piles.'' A more complete description of the hypothesis and the ensuing dynamics is provided there. From that study a framework of asteroid evolution is assembled. It is determined that mass ratio is the most important factor for determining the outcome of a rotational fission event. Each observed binary morphology is tied to this evolutionary schema and the relevant timescales are assessed. In the second study, the role of non-gravitational and tidal torques in binary asteroid systems is explored. Understanding the competition between tides and the YORP effect provides insight into the relative abundances of the different binary morphologies and the effect of planetary flybys. The interplay between tides and the BYORP effect creates dramatic evolutionary pathways that lead to interesting end states including stranded

Photon collisions as a glueball source

International Nuclear Information System (INIS)

Liu, H.C.

1984-01-01

Photon-photon and photon-nucleon collisions are suggested as a glueball source at small x in the collision center-of-mass frame. The glueball-production cross section is estimated through the two-gluon-fusion mechanism in perturbative quantum chromodynamics. The pointlike component of the photon structure function has a distinctive feature in that it consists almost purely of gluons at small x, which turns out to be very effective in producing glueballs. A much larger signal-to-noise ratio is expected in the glueball search in high-energy photon-photon and photon-nucleon collisions compared with hadron-hadron collisions. It is argued that the background due to soft collisions of the photons can be effectively reduced

Understanding Kaula's Rule for Small Bodies

Science.gov (United States)

McMahon, J.; Scheeres, D. J.; Farnocchia, D.; Chesley, S.

2015-12-01

Kaula's rule gives a bound on the RMS of the gravity coefficients of each order as a power law K/n^2, where n is the degree. Kaula derived the value of K for Earth as 10-5. This rule has been used as an a priori information bound on the gravity coefficients of other planetary bodies before their gravity fields are measured by spacecraft. To apply Kaula's rule to other bodies, the simple scaling based on the relative gravity of each body is used - (gEarth/gPlanet)2. This scaling was successfully used even for Vesta, where K = 0.011. However, if Kaula's rule is applied to very small bodies, such as the OSIRIS-REx target asteroid Bennu, the scaling results in un-useable bounds. In this case, K ~ 105. This fact has motivated further investigation into the derivation and application of a Kaula-like power rule to bound the gravity field of small bodies. Our initial investigation focuses on the specific application to Bennu. This study is enabled by the fact that a fairly accurate shape model of Bennu has been derived based on three Earth-based radar apparitions along with a constrained bulk density based on astrometry and thermal measurements. Thus we investigated varying the Bennu topography within the expected accuracy of the shape model as well as the density distribution. Several interesting facts were discovered through this analysis. First, the top shape of Bennu, common to a number of near-Earth asteroids, results in the even zonal coefficients being larger than the odd zonal of one lower degree. Second, the zonals in general are significantly larger than the coefficients with order > 1, so that the zonals will dominate any fitting of K to a power law. This encourages us to have one K for the absolute value of the zonals (K=0.087), and a separate value for the RMS of the other coefficients (K=0.026). Third, variation in the topography within this uncertainty dominates the variation in the gravity field coefficients over basic inhomogenous density distribution

Accurate Treatment of Collisions and Water-Delivery in Models of Terrestrial Planet Formation

Science.gov (United States)

Haghighipour, Nader; Maindl, Thomas; Schaefer, Christoph

2017-10-01

It is widely accepted that collisions among solid bodies, ignited by their interactions with planetary embryos is the key process in the formation of terrestrial planets and transport of volatiles and chemical compounds to their accretion zones. Unfortunately, due to computational complexities, these collisions are often treated in a rudimentary way. Impacts are considered to be perfectly inelastic and volatiles are considered to be fully transferred from one object to the other. This perfect-merging assumption has profound effects on the mass and composition of final planetary bodies as it grossly overestimates the masses of these objects and the amounts of volatiles and chemical elements transferred to them. It also entirely neglects collisional-loss of volatiles (e.g., water) and draws an unrealistic connection between these properties and the chemical structure of the protoplanetary disk (i.e., the location of their original carriers). We have developed a new and comprehensive methodology to simulate growth of embryos to planetary bodies where we use a combination of SPH and N-body codes to accurately model collisions as well as the transport/transfer of chemical compounds. Our methodology accounts for the loss of volatiles (e.g., ice sublimation) during the orbital evolution of their careers and accurately tracks their transfer from one body to another. Results of our simulations show that traditional N-body modeling of terrestrial planet formation overestimates the amount of the mass and water contents of the final planets by over 60% implying that not only the amount of water they suggest is far from being realistic, small planets such as Mars can also form in these simulations when collisions are treated properly. We will present details of our methodology and discuss its implications for terrestrial planet formation and water delivery to Earth.

Rearrangement and energy transfer collisions of few-body molecular systems

International Nuclear Information System (INIS)

Gentry, W.R.

1981-01-01

A great variety of experimental techniques now makes it possible to obtain dynamical information on single bimolecular collisions in a very direct way. These methods are too numerous to permit a comprehensive review in this article, but a few examples have been chosen to illustrate briefly the types of results being obtained in several areas. These include measurements of state-to-state differential cross sections for rotationally and vibrationally inelastic collisions, and rearrangement collisions studies by crossed-beam and merged-beam methods. (orig.)

Small-Body Extensions for the Satellite Orbit Analysis Program (SOAP)

Science.gov (United States)

Carnright, Robert; Stodden, David; Coggi, John

2008-01-01

An extension to the SOAP software allows users to work with tri-axial ellipsoid-based representations of planetary bodies, primarily for working with small, natural satellites, asteroids, and comets. SOAP is a widely used tool for the visualization and analysis of space missions. The small body extension provides the same visualization and analysis constructs for use with small bodies. These constructs allow the user to characterize satellite path and instrument cover information for small bodies in both 3D display and numerical output formats. Tri-axial ellipsoids are geometric shapes the diameters of which are different in each of three principal x, y, and z dimensions. This construct provides a better approximation than using spheres or oblate spheroids (ellipsoids comprising two common equatorial diameters as a distinct polar diameter). However, the tri-axial ellipsoid is considerably more difficult to work with from a modeling perspective. In addition, the SOAP small-body extensions allow the user to actually employ a plate model for highly irregular surfaces. Both tri-axial ellipsoids and plate models can be assigned to coordinate frames, thus allowing for the modeling of arbitrary changes to body orientation. A variety of features have been extended to support tri-axial ellipsoids, including the computation and display of the spacecraft sub-orbital point, ground trace, instrument footprints, and swathes. Displays of 3D instrument volumes can be shown interacting with the ellipsoids. Longitude/latitude grids, contour plots, and texture maps can be displayed on the ellipsoids using a variety of projections. The distance along an arbitrary line of sight can be computed between the spacecraft and the ellipsoid, and the coordinates of that intersection can be plotted as a function of time. The small-body extension supports the same visual and analytical constructs that are supported for spheres and oblate spheroids in SOAP making the implementation of the more

Towards relativistic heavy ion collisions by small steps towards the stars. [Review

Energy Technology Data Exchange (ETDEWEB)

Scott, D.K.

1979-03-01

A review lecture is given on current attempts to search for the exotic processes occurring in relativistic heavy ion collisions. From peripheral collisions the discussion proceeds to central collisions and lastly the search for the exotic, in which the tools developed for the study of peripheral and central collisions are used. 200 references. (JFP)

Asymptotic form of the charge-exchange cross section in three-body rearrangement collisions

Science.gov (United States)

Omidvar, K.

1975-01-01

A three-body general-type rearrangement collision is considered in which the initial and final bound states are described by hydrogen-like wave functions. It is shown that the charge-exchange amplitude in the first Born approximation can be expanded at all incident energies in terms of the inverse powers of the principal quantum number (n). By expanding the exchange amplitude in this way, it is demonstrated conclusively that the cross section for capture into the s, p, and d states as well as for the sum over all the angular-momentum states is proportional to 1/n-cubed plus terms proportional to higher inverse odd powers of n. It is found that the low-lying levels cannot be scaled to the 1/n-cubed law irrespective of the value of the incident energy except in the case of capture into the s states in accordance with the Oppenheimer-Brinkman-Kramers approximation. Zeros and minima in the differential cross sections are given in the limit of high principal quantum number for electron capture by protons from atomic hydrogen and for positronium formation by proton-atomic hydrogen collisions.

Trait-based prediction of extinction risk of small-bodied freshwater fishes.

Science.gov (United States)

Kopf, R Keller; Shaw, Casey; Humphries, Paul

2017-06-01

Small body size is generally correlated with r-selected life-history traits, including early maturation, short-generation times, and rapid growth rates, that result in high population turnover and a reduced risk of extinction. Unlike other classes of vertebrates, however, small freshwater fishes appear to have an equal or greater risk of extinction than large fishes. We explored whether particular traits explain the International Union for Conservation of Nature (IUCN) Red List conservation status of small-bodied freshwater fishes from 4 temperate river basins: Murray-Darling, Australia; Danube, Europe; Mississippi-Missouri, North America; and the Rio Grande, North America. Twenty-three ecological and life-history traits were collated for all 171 freshwater fishes of ≤120 mm total length. We used generalized linear mixed-effects models to assess which combination of the 23 traits best explained whether a species was threatened or not threatened. We used the best models to predict the probability of 29 unclassified species being listed as threatened. With and without controlling for phylogeny at the family level, small body size-among small-bodied species-was the most influential trait correlated with threatened species listings. The k-folds cross-validation demonstrated that body size and a random effect structure that included family predicted the threat status with an accuracy of 78% (SE 0.5). We identified 10 species likely to be threatened that are not listed as such on the IUCN Red List. Small body size is not a trait that provides universal resistance to extinction, particularly for vertebrates inhabiting environments affected by extreme habitat loss and fragmentation. We hypothesize that this is because small-bodied species have smaller home ranges, lower dispersal capabilities, and heightened ecological specialization relative to larger vertebrates. Trait data and further model development are needed to predict the IUCN conservation status of the over 11

Comparison of many bodied and binary collision cascade models up to 1 keV

International Nuclear Information System (INIS)

Schwartz, D.M.; Schiffgens, J.D.; Doran, D.G.; Odette, G.R.; Ariyasu, R.G.

1976-01-01

A quasi-dynamical code ADDES has been developed to model displacement cascades in copper for primary knockon atom energies up to several keV. ADDES is like a dynamical code in that it employs a many body treatment, yet similar to a binary collision code in that it incorporates the basic assumption that energy transfers below several eV can be ignored in describing cascade evolution. This paper is primarily concerned with (1) a continuing effort to validate the assumptions and specific parameters in the code by the comparison of ADDES results with experiment and with results from a dynamical code, and (2) comparisons of ADDES results with those from a binary collision code. The directional dependence of the displacement threshold is in reasonable agreement with the measurements of Jung et al. The behavior of focused replacement sequences is very similar to that obtained with the dynamical codes GRAPE and COMENT. Qualitative agreement was found between ADDES and COMENT for a higher energy (500 eV) defocused event while differences, still under study, are apparent in a 250 eV high index event. Comparisons of ADDES with the binary collision code MARLOWE show surprisingly good agreement in the 250 to 1000 eV range for both number and separation of Frenkel pairs. A preliminary observation, perhaps significant to displacement calculations utilizing the concept of a mean displacement energy, is the dissipation of 300 to 400 eV in a replacement sequence producing a single interstitial

Granular media in the context of small bodies

Science.gov (United States)

Tancredi, G.

2014-07-01

Granular materials of different particle sizes are present on the surface and the interior of several atmosphereless Solar System bodies. The presence of very fine particles on the surface of the Moon, the so-called regolith, was confirmed by the Apollo astronauts. From the polarimetric observations and phase angle curves, it is possible to indirectly infer the presence of fine particles on the surfaces of asteroids and planetary satellites. More recently, the visit of spacecraft to several asteroids and comets has provided us with close pictures of the surface, where particles of a wide size range from cm to hundreds of meters have been directly observed. The presence of even finer particles on the visited bodies can also be inferred from image analysis. Solar System bodies smaller than a few hundred km may have a variety of internal structures: monolithic single bodies, objects with internal fractures, rubble piles maintained as a single object by self-gravity, etc. After the visit of the small asteroid Itokawa, it has been speculated that ''some small asteroids appear to be clumps of gravel glued by a very weak gravity field'' (Asphaug 2007). We still do not know the internal structure of these rubble piles and the size distribution of the interior constituents, but these clumps could have several million meter-sized boulders inside. There are several pieces of evidence that many asteroids are agglomerates of small components, like: - Rotation periods for small asteroids - Tidal disruption of asteroids and comets when they enter the Roche's limit of a massive object - The existence of crater chains like the ones observed in Ganymede - Low density estimates (laboratory experiments on granular material trying to reproduce the conditions in space: vacuum and low gravity. We describe the experimental set-ups and some results of these experiments. Some open problems and future line of work in this field will be presented.

Three body mechanisms in hadron collisions. The A = 3 system

International Nuclear Information System (INIS)

Frascaria, R.

1988-01-01

Three-body mechanisms in hadron collisions, and the role of the A = 3 system are reviewed, and the excitation functions of the proton deuteron system in interactions at energies up to 2.9 GeV are discussed. Meson productions at large angles reveal structures due to the mesonic degrees of freedom in the interaction of the proton with the deuteron, exciting n * isobars in intermediate states. Propagation in the nuclei does not seem to change the properties of these isobars. The meson double scattering mechanism provides a way to understand coherent meson production in pd capture. It is difficult to say whether this coherent process corresponds to eigenstates of the A = 3 system. The sharing of the momentum transfer between the three nucleons renders impossible the observation of high momentum components in coherent proton captures. The possible contribution of the electromagnetic probe in hadron physics with a multi GeV electron accelerator is mentioned

A qualitative evaluation of owner and worker health and safety beliefs in small auto collision repair shops.

Science.gov (United States)

Parker, David L; Bejan, Anca; Brosseau, Lisa M

2012-05-01

About 223,000 people are employed in approximately 34,500 auto collision repair businesses. In general, employees and owners in these establishments lack knowledge of health and safety practices and do not have the technical expertise to make their place of work safer. Three employee and three owner focus groups were conducted. The goal of these focus groups was to characterize health and safety beliefs of owners and employees and to determine the best methods for motivating safety improvements in collision repair shops. A total of 11 owners and 19 workers participated in these focus groups. Employees and owners were aware of a wide range of hazards. Both groups noted difficulty in staying informed. Employers were hesitant to set and enforce safety and health rules. Employees perceive owners to be unwilling to dedicate the resources to make the workplace safer and provide personal protective equipment. Both groups felt insurance reimbursement practices placed undue pressure on employees. Focus groups provide important insights into intervention development in very small enterprises in general and auto collision shops in specific. Employers were conflicted about allowing employees a certain level of independence while also maintaining a safe workplace. From the employee perspective, owners frequently fail to provide adequate personal protective equipment and make improvements needed to ensure safe work. The unique managerial needs of very small enterprises must be accounted for if health and safety programs are to be implemented in these establishments. Copyright © 2012 Wiley Periodicals, Inc.

Realizing all reduced syzygy sequences in the planar three-body problem

International Nuclear Information System (INIS)

Moeckel, Richard; Montgomery, Richard

2015-01-01

The configuration space of the planar three-body problem, reduced by rotations and with collisions excluded, has a rich topology which supports a large set of free homotopy classes. These classes have a simple description in terms of syzygy (or eclipse) sequences. Each homotopy class corresponds to a unique ‘reduced’ syzygy sequence. We prove that each reduced syzygy sequence is realized by a periodic solution of the rotation-reduced Newtonian planar three-body problem. The realizing solutions have small, nonzero angular momentum, repeatedly come very close to triple collision, and have lots of ‘stutters’—repeated syzygies of the same type, which cancel out up to homotopy. The heart of the proof stems from the work by one of us on symbolic dynamics arising out of the central configurations after the triple collision is blown up using McGehee's method. We end with a list of open problems. (paper)

Time Dependence of Collision Probabilities During Satellite Conjunctions

Science.gov (United States)

Hall, Doyle T.; Hejduk, Matthew D.; Johnson, Lauren C.

2017-01-01

The NASA Conjunction Assessment Risk Analysis (CARA) team has recently implemented updated software to calculate the probability of collision (P (sub c)) for Earth-orbiting satellites. The algorithm can employ complex dynamical models for orbital motion, and account for the effects of non-linear trajectories as well as both position and velocity uncertainties. This “3D P (sub c)” method entails computing a 3-dimensional numerical integral for each estimated probability. Our analysis indicates that the 3D method provides several new insights over the traditional “2D P (sub c)” method, even when approximating the orbital motion using the relatively simple Keplerian two-body dynamical model. First, the formulation provides the means to estimate variations in the time derivative of the collision probability, or the probability rate, R (sub c). For close-proximity satellites, such as those orbiting in formations or clusters, R (sub c) variations can show multiple peaks that repeat or blend with one another, providing insight into the ongoing temporal distribution of risk. For single, isolated conjunctions, R (sub c) analysis provides the means to identify and bound the times of peak collision risk. Additionally, analysis of multiple actual archived conjunctions demonstrates that the commonly used “2D P (sub c)” approximation can occasionally provide inaccurate estimates. These include cases in which the 2D method yields negligibly small probabilities (e.g., P (sub c)) is greater than 10 (sup -10)), but the 3D estimates are sufficiently large to prompt increased monitoring or collision mitigation (e.g., P (sub c) is greater than or equal to 10 (sup -5)). Finally, the archive analysis indicates that a relatively efficient calculation can be used to identify which conjunctions will have negligibly small probabilities. This small-P (sub c) screening test can significantly speed the overall risk analysis computation for large numbers of conjunctions.

Nuclear quantum many-body dynamics: from collective vibrations to heavy-ion collisions

International Nuclear Information System (INIS)

Simenel, Cedric

2012-01-01

This report gives a summary of my research on nuclear dynamics during the past ten years. The choice of this field has been motivated by the desire to understand the physics of complex systems obeying quantum mechanics. In particular, the interplay between collective motion and single-particle degrees of freedom is a source of complex and fascinating behaviours. For instance, giant resonances are characterised by a collective vibration of many nucleons, but their decay may occur by the emission of a single nucleon. Another example could be taken from the collision of nuclei where the transfer of few nucleons may have a strong impact on the formation of a compound system is non trivial. To describe these complex systems, one needs to solve the quantum many-body problem. The description of the dynamics of composite systems can be very challenging, especially when two such systems interact. An important goal of nuclear physics is to find a unified way to describe the dynamics of nuclear systems. Ultimately, the same theoretical model should be able to describe vibrations, rotations, fission, all the possible outcomes of heavy-ion collisions (elastic and inelastic scattering, particle transfer, fusion, and multifragmentation), and even the dynamics of neutron star crust. This desire for a global approach to nuclear dynamics has strongly influenced my research activities. In particular, all the numerical applications presented in this report have been obtained from few numerical codes solving equations derived from the same variational principle. Beside the quest for a unified model of nuclear dynamics, possible applications of heavy-ion collisions such as the formation of new nuclei is also a strong motivation for the experimental and theoretical studies of reaction mechanisms. This report is not a review article, but should be considered as a reading guide of the main papers my collaborators and myself have published. It also gives the opportunity to detail some

Case studies in atomic collision physics

CERN Document Server

McDaniel, Earl Wadsworth

1972-01-01

Case Studies in Atomic Collision Physics II focuses on studies on the role of atomic collision processes in astrophysical plasmas, including ionic recombination, electron transport, and position scattering. The book first discusses three-body recombination of positive and negative ions, as well as introduction to ionic recombination, calculation of the recombination coefficient, ions recombining in their parent gas, and three-body recombination at moderate and high gas-densities. The manuscript also takes a look at precision measurements of electron transport coefficients and differential cr

An investigation of collision propagation in energetic ion initiated cascades in copper

International Nuclear Information System (INIS)

Chakarov, I.R.; Webb, R.P.; Smith, R.; Beardmore, K.

1995-01-01

Using simple Binary Collision simulations of energetic ion initiated collision cascades, particles are considered to undergo a series of binary collisions with their surroundings. In Molecular Dynamics simulation it is difficult to even define what is meant by a collision as the interaction potentials are infinite in nature and consequently all particles are considered to interact with all other particles. By making a suitable definition of a collision for Molecular Dynamics we are able to compare the temporal behaviour of the number of collisions occurring during the propagation of a collision cascade between the two different calculation schemes. An investigation is made of the number of collisions as a function of time occurring in collision cascades. We compare these results to the time ordered version of MARLOWE. By making further definitions about what makes a many body collision, we further investigate the numbers of many body collisions occurring during a number of collision cascades. (orig.)

Small UAV Automatic Ground Collision Avoidance System Design Considerations and Flight Test Results

Science.gov (United States)

Sorokowski, Paul; Skoog, Mark; Burrows, Scott; Thomas, SaraKatie

2015-01-01

The National Aeronautics and Space Administration (NASA) Armstrong Flight Research Center Small Unmanned Aerial Vehicle (SUAV) Automatic Ground Collision Avoidance System (Auto GCAS) project demonstrated several important collision avoidance technologies. First, the SUAV Auto GCAS design included capabilities to take advantage of terrain avoidance maneuvers flying turns to either side as well as straight over terrain. Second, the design also included innovative digital elevation model (DEM) scanning methods. The combination of multi-trajectory options and new scanning methods demonstrated the ability to reduce the nuisance potential of the SUAV while maintaining robust terrain avoidance. Third, the Auto GCAS algorithms were hosted on the processor inside a smartphone, providing a lightweight hardware configuration for use in either the ground control station or on board the test aircraft. Finally, compression of DEM data for the entire Earth and successful hosting of that data on the smartphone was demonstrated. The SUAV Auto GCAS project demonstrated that together these methods and technologies have the potential to dramatically reduce the number of controlled flight into terrain mishaps across a wide range of aviation platforms with similar capabilities including UAVs, general aviation aircraft, helicopters, and model aircraft.

Restricted Collision List method for faster Direct Simulation Monte-Carlo (DSMC) collisions

Energy Technology Data Exchange (ETDEWEB)

Macrossan, Michael N., E-mail: m.macrossan@uq.edu.au

2016-08-15

The ‘Restricted Collision List’ (RCL) method for speeding up the calculation of DSMC Variable Soft Sphere collisions, with Borgnakke–Larsen (BL) energy exchange, is presented. The method cuts down considerably on the number of random collision parameters which must be calculated (deflection and azimuthal angles, and the BL energy exchange factors). A relatively short list of these parameters is generated and the parameters required in any cell are selected from this list. The list is regenerated at intervals approximately equal to the smallest mean collision time in the flow, and the chance of any particle re-using the same collision parameters in two successive collisions is negligible. The results using this method are indistinguishable from those obtained with standard DSMC. The CPU time saving depends on how much of a DSMC calculation is devoted to collisions and how much is devoted to other tasks, such as moving particles and calculating particle interactions with flow boundaries. For 1-dimensional calculations of flow in a tube, the new method saves 20% of the CPU time per collision for VSS scattering with no energy exchange. With RCL applied to rotational energy exchange, the CPU saving can be greater; for small values of the rotational collision number, for which most collisions involve some rotational energy exchange, the CPU may be reduced by 50% or more.

NASA Lewis Launch Collision Probability Model Developed and Analyzed

Science.gov (United States)

Bollenbacher, Gary; Guptill, James D

1999-01-01

There are nearly 10,000 tracked objects orbiting the earth. These objects encompass manned objects, active and decommissioned satellites, spent rocket bodies, and debris. They range from a few centimeters across to the size of the MIR space station. Anytime a new satellite is launched, the launch vehicle with its payload attached passes through an area of space in which these objects orbit. Although the population density of these objects is low, there always is a small but finite probability of collision between the launch vehicle and one or more of these space objects. Even though the probability of collision is very low, for some payloads even this small risk is unacceptable. To mitigate the small risk of collision associated with launching at an arbitrary time within the daily launch window, NASA performs a prelaunch mission assurance Collision Avoidance Analysis (or COLA). For the COLA of the Cassini spacecraft, the NASA Lewis Research Center conducted an in-house development and analysis of a model for launch collision probability. The model allows a minimum clearance criteria to be used with the COLA analysis to ensure an acceptably low probability of collision. If, for any given liftoff time, the nominal launch vehicle trajectory would pass a space object with less than the minimum required clearance, launch would not be attempted at that time. The model assumes that the nominal positions of the orbiting objects and of the launch vehicle can be predicted as a function of time, and therefore, that any tracked object that comes within close proximity of the launch vehicle can be identified. For any such pair, these nominal positions can be used to calculate a nominal miss distance. The actual miss distances may differ substantially from the nominal miss distance, due, in part, to the statistical uncertainty of the knowledge of the objects positions. The model further assumes that these position uncertainties can be described with position covariance matrices

Miocene small-bodied ape from Eurasia sheds light on hominoid evolution.

Science.gov (United States)

Alba, David M; Almécija, Sergio; DeMiguel, Daniel; Fortuny, Josep; Pérez de los Ríos, Miriam; Pina, Marta; Robles, Josep M; Moyà-Solà, Salvador

2015-10-30

Miocene small-bodied anthropoid primates from Africa and Eurasia are generally considered to precede the divergence between the two groups of extant catarrhines—hominoids (apes and humans) and Old World monkeys—and are thus viewed as more primitive than the stem ape Proconsul. Here we describe Pliobates cataloniae gen. et sp. nov., a small-bodied (4 to 5 kilograms) primate from the Iberian Miocene (11.6 million years ago) that displays a mosaic of primitive characteristics coupled with multiple cranial and postcranial shared derived features of extant hominoids. Our cladistic analyses show that Pliobates is a stem hominoid that is more derived than previously described small catarrhines and Proconsul. This forces us to reevaluate the role played by small-bodied catarrhines in ape evolution and provides key insight into the last common ancestor of hylobatids (gibbons) and hominids (great apes and humans). Copyright © 2015, American Association for the Advancement of Science.

Binary collisions in popovici’s photogravitational model

Directory of Open Access Journals (Sweden)

Mioc V.

2002-01-01

Full Text Available The dynamics of bodies under the combined action of the gravitational attraction and the radiative repelling force has large and deep implications in astronomy. In the 1920s, the Romanian astronomer Constantin Popovici proposed a modified photogravitational law (considered by other scientists too. This paper deals with the collisions of the two-body problem associated with Popovici’s model. Resorting to McGehee-type transformations of the second kind, we obtain regular equations of motion and define the collision manifold. The flow on this boundary manifold is wholly described. This allows to point out some important qualitative features of the collisional motion: existence of the black-hole effect, gradientlikeness of the flow on the collision manifold, regularizability of collisions under certain conditions. Some questions, coming from the comparison of Levi-Civita’s regularizing transformations and McGehee’s ones, are formulated.

What Happens Where the Water and the Rock Touch in Small Space Bodies

Science.gov (United States)

Byrne, P. K.; Regensburger, P. V.; Klimczak, C.; Bohnenstiehl, D. R.; Dombard, A. J.; Hauck, S. A., II

2017-12-01

There are several small space bodies that go around bigger worlds that might have a layer of water under a layer of ice. Lots of study has been done to understand the outside ice layer of these small space bodies, because the ice can tells us important things about the big water layer under it. Some of these small space bodies are very interesting because the right things for life—water, hot rock, and food—might be at the bottom of the water layer, where it touches the top of the next layer down, which is made of rock. But it is very hard to understand what this rock at the bottom of the water is like, because we can't see it. So, we are imagining what this rock is like by thinking about what the rock is like under the water layer on our own world. If hot rock comes out of the rock layer through cracks under the water, the cold of the water makes the hot rock go very cold very fast, and it makes funny rolls as it does so. This might happen on some small space bodies that are hot enough on the inside to make hot rock. We know that on our own world the rock layer under the water is wet to as far down as cracks can go, so it makes sense that this is true for small space bodies, too. We did some thinking about numbers and found out that the cracks can go a few ten hundred steps into the rock layer on small space bodies, but for bigger (well, not quite so small) space bodies, the cracks can go at least tens of ten hundred steps into the rock layer. This means that water goes into the rock layer this much, too. But get this: some small bodies are not really that small—one of them is bigger than the first world from the Sun! And on a few of these big (small) bodies, the layer of water is so heavy that the bottom of that water is pushed together from all sides and turns into a type of hot ice. This means that, for these big (small) worlds, the water can't get into the rock layer through cracks (since there is a layer of hot ice in the way), and so these bodies are

Pauli-blocking effect in two-body collisions dominates the in-medium effects in heavy-ion reactions near Fermi energy

Energy Technology Data Exchange (ETDEWEB)

Xing, Yong-Zhong, E-mail: yzxing@tsnu.edu.cn [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); Zhang, H.F. [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Liu, Xiao-Bin [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); Zheng, Yu-Ming [Institute for the Fundamental Physics, Tianshui Normal University, Gansu, Tianshui 741000 (China); China Institute of Atomic Energy, P.O. Box 275(18), Beijing 102413 (China)

2017-01-15

The dissipation phenomenon in the heavy-ion reaction at incident energy near Fermi energy is studied by simulating the reactions {sup 129}Xe + {sup 129}Sn and {sup 58}Ni + {sup 58}Ni with isospin-dependent quantum molecular dynamics model (IQMD). The isotropy ratio in terms of transverse and longitudinal energies of the free protons emitted in the final states of these reactions is quantitatively analyzed to explore the in-medium correlation of the binary collisions. Comparison of the calculations with the experimental data recently released by INDRA collaboration exhibits that the ratio is very sensitive to the Pauli blocking effect in two-body collisions and Pauli exclusion principle is indispensable in the theoretical simulations for the heavy-ion reactions near the Fermi energy.

Measurement of four-particle cumulants and symmetric cumulants with subevent methods in small collision systems with the ATLAS detector

CERN Document Server

Derendarz, Dominik; The ATLAS collaboration

2018-01-01

Measurements of symmetric cumulants SC(n,m)=⟨v2nv2m⟩−⟨v2n⟩⟨v2m⟩ for (n,m)=(2,3) and (2,4) and asymmetric cumulant AC(n) are presented in pp, p+Pb and peripheral Pb+Pb collisions at various collision energies, aiming to probe the long-range collective nature of multi-particle production in small systems. Results are obtained using the standard cumulant method, as well as the two-subevent and three-subevent cumulant methods. Results from the standard method are found to be strongly biased by non-flow correlations as indicated by strong sensitivity to the chosen event class definition. A systematic reduction of non-flow effects is observed when using the two-subevent method and the results become independent of event class definition when the three-subevent method is used. The measured SC(n,m) shows an anti-correlation between v2 and v3, and a positive correlation between v2 and v4. The magnitude of SC(n,m) is constant with Nch in pp collisions, but increases with Nch in p+Pb and Pb+Pb collisions. ...

Criteria for applicability of the impulse approach to collisions

International Nuclear Information System (INIS)

Sharma, R.D.; Bakshi, P.M.; Sindoni, J.M.

1990-01-01

Using an exact formulation of impulse approach (IA) to atom-diatom collisions, we assess its internal consistency. By comparing the cross sections in the forward and reverse directions for the vibrational-rotational inelastic processes, using the half-on-the-shell (post and prior) models of the two-body t matrix, we show that in both cases the IA leads to a violation of the semidetailed balance (SDB) condition for small scattering angles. An off-shell model for the two-body t matrix, which preserves SDB, is shown to have other serious shortcomings. The cross sections are studied quantitatively as a function of the relative translational energy and the mass of the incident particle, and criteria discussed for the applicability of IA

Robotic Reconnaissance Missions to Small Bodies and Their Potential Contributions to Human Exploration

Science.gov (United States)

Abell, P. A.; Rivkin, A. S.

2015-01-01

Introduction: Robotic reconnaissance missions to small bodies will directly address aspects of NASA's Asteroid Initiative and will contribute to future human exploration. The NASA Asteroid Initiative is comprised of two major components: the Grand Challenge and the Asteroid Mission. The first component, the Grand Challenge, focuses on protecting Earth's population from asteroid impacts by detecting potentially hazardous objects with enough warning time to either prevent them from impacting the planet, or to implement civil defense procedures. The Asteroid Mission involves sending astronauts to study and sample a near- Earth asteroid (NEA) prior to conducting exploration missions of the Martian system, which includes Phobos and Deimos. The science and technical data obtained from robotic precursor missions that investigate the surface and interior physical characteristics of an object will help identify the pertinent physical properties that will maximize operational efficiency and reduce mission risk for both robotic assets and crew operating in close proximity to, or at the surface of, a small body. These data will help fill crucial strategic knowledge gaps (SKGs) concerning asteroid physical characteristics that are relevant for human exploration considerations at similar small body destinations. Small Body Strategic Knowledge Gaps: For the past several years NASA has been interested in identifying the key SKGs related to future human destinations. These SKGs highlight the various unknowns and/or data gaps of targets that the science and engineering communities would like to have filled in prior to committing crews to explore the Solar System. An action team from the Small Bodies Assessment Group (SBAG) was formed specifically to identify the small body SKGs under the direction of the Human Exploration and Operations Missions Directorate (HEOMD), given NASA's recent interest in NEAs and the Martian moons as potential human destinations [1]. The action team

Automated Detection of Small Bodies by Space Based Observation

Science.gov (United States)

Bidstrup, P. R.; Grillmayer, G.; Andersen, A. C.; Haack, H.; Jorgensen, J. L.

The number of known comets and asteroids is increasing every year. Up till now this number is including approximately 250,000 of the largest minor planets, as they are usually referred. These discoveries are due to the Earth-based observation which has intensified over the previous decades. Additionally larger telescopes and arrays of telescopes are being used for exploring our Solar System. It is believed that all near- Earth and Main-Belt asteroids of diameters above 10 to 30 km have been discovered, leaving these groups of objects as observationally complete. However, the cataloguing of smaller bodies is incomplete as only a very small fraction of the expected number has been discovered. It is estimated that approximately 1010 main belt asteroids in the size range 1 m to 1 km are too faint to be observed using Earth-based telescopes. In order to observe these small bodies, space-based search must be initiated to remove atmospheric disturbances and to minimize the distance to the asteroids and thereby minimising the requirement for long camera integration times. A new method of space-based detection of moving non-stellar objects is currently being developed utilising the Advanced Stellar Compass (ASC) built for spacecraft attitude determination by Ørsted, Danish Technical University. The ASC serves as a backbone technology in the project as it is capable of fully automated distinction of known and unknown celestial objects. By only processing objects of particular interest, i.e. moving objects, it will be possible to discover small bodies with a minimum of ground control, with the ultimate ambition of a fully automated space search probe. Currently, the ASC is being mounted on the Flying Laptop satellite of the Institute of Space Systems, Universität Stuttgart. It will, after a launch into a low Earth polar orbit in 2008, test the detection method with the ASC equipment that already had significant in-flight experience. A future use of the ASC based automated

Quasi-four-body treatment of charge transfer in the collision of protons with atomic helium: II. Second-order non-Thomas mechanisms and the cross sections

Science.gov (United States)

Safarzade, Zohre; Akbarabadi, Farideh Shojaei; Fathi, Reza; Brunger, Michael J.; Bolorizadeh, Mohammad A.

2018-05-01

A fully quantum mechanical four-body treatment of charge transfer collisions between energetic protons and atomic helium is developed here. The Pauli exclusion principle is applied to both the wave function of the initial and final states as well as the operators involved in the interaction. Prior to the collision, the helium atom is assumed as a two-body system composed of the nucleus, He2+, and an electron cloud composed of two electrons. Nonetheless, four particles are assumed in the final state. As the double interactions contribute extensively in single charge transfer collisions, the Faddeev-Lovelace-Watson scattering formalism describes it best physically. The treatment of the charge transfer cross section, under this quasi-four-body treatment within the FWL formalism, showed that other mechanisms leading to an effect similar to the Thomas one occur at the same scattering angle. Here, we study the two-body interactions which are not classically described but which lead to an effect similar to the Thomas mechanism and finally we calculate the total singlet and triplet amplitudes as well as the angular distributions of the charge transfer cross sections. As the incoming projectiles are assumed to be plane waves, the present results are calculated for high energies; specifically a projectile energy of 7.42 MeV was assumed as this is where experimental results are available in the literature for comparison. Finally, when possible we compare the present results with the other available theoretical data.

Robotic Missions to Small Bodies and Their Potential Contributions to Human Exploration and Planetary Defense

Science.gov (United States)

Abell, Paul A.; Rivkin, Andrew S.

2015-01-01

Introduction: Robotic missions to small bodies will directly address aspects of NASA's Asteroid Initiative and will contribute to future human exploration and planetary defense. The NASA Asteroid Initiative is comprised of two major components: the Grand Challenge and the Asteroid Mission. The first component, the Grand Challenge, focuses on protecting Earth's population from asteroid impacts by detecting potentially hazardous objects with enough warning time to either prevent them from impacting the planet, or to implement civil defense procedures. The Asteroid Mission involves sending astronauts to study and sample a near-Earth asteroid (NEA) prior to conducting exploration missions of the Martian system, which includes Phobos and Deimos. The science and technical data obtained from robotic precursor missions that investigate the surface and interior physical characteristics of an object will help identify the pertinent physical properties that will maximize operational efficiency and reduce mission risk for both robotic assets and crew operating in close proximity to, or at the surface of, a small body. These data will help fill crucial strategic knowledge gaps (SKGs) concerning asteroid physical characteristics that are relevant for human exploration considerations at similar small body destinations. These data can also be applied for gaining an understanding of pertinent small body physical characteristics that would also be beneficial for formulating future impact mitigation procedures. Small Body Strategic Knowledge Gaps: For the past several years NASA has been interested in identifying the key SKGs related to future human destinations. These SKGs highlight the various unknowns and/or data gaps of targets that the science and engineering communities would like to have filled in prior to committing crews to explore the Solar System. An action team from the Small Bodies Assessment Group (SBAG) was formed specifically to identify the small body SKGs under the

First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

Energy Technology Data Exchange (ETDEWEB)

Varghese, Jithin J.; Mushrif, Samir H., E-mail: shmushrif@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore)

2015-05-14

Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu{sub n} where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH{sub 3} and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH{sub x} (x = 1–3) species and recombination of H with CH{sub x} have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters.

First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

International Nuclear Information System (INIS)

Varghese, Jithin J.; Mushrif, Samir H.

2015-01-01

Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu n where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH 3 and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH x (x = 1–3) species and recombination of H with CH x have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters

Introduction to the study of collisions between heavy nuclei

International Nuclear Information System (INIS)

Bayman, B.F.

1980-01-01

Current investigations concerning the collisions of nuclei governed by small de Broglie wavelengths are reviewed. The wave packets localize nuclei in regions small compared to their diameters. Cross sections are examined for potential scattering, elastic scattering, quasi-molecular states, peripheral particle-transfer reactions, fusion, and deep inelastic collisions. Theories of fusion and deep inelastic collisions are summarized. This paper is in the nature of a review-tutorial. 45 references, 51 figures, 2 tables

Search for the pair production of third-generation squarks with two-body decays to a bottom or charm quark and a neutralino in proton-proton collisions at $ \\sqrt{s} = $ 13 TeV

CERN Document Server

Sirunyan, Albert M; CMS Collaboration; Adam, Wolfgang; Ambrogi, Federico; Asilar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Grossmann, Johannes; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krammer, Natascha; Krätschmer, Ilse; Liko, Dietrich; Madlener, Thomas; Mikulec, Ivan; Pree, Elias; Rabady, Dinyar; Rad, Navid; Rohringer, Herbert; Schieck, Jochen; Schöfbeck, Robert; Spanring, Markus; Spitzbart, Daniel; Strauss, Josef; Waltenberger, Wolfgang; Wittmann, Johannes; Wulz, Claudia-Elisabeth; Zarucki, Mateusz; Chekhovsky, Vladimir; Suarez Gonzalez, Juan; De Wolf, Eddi A; Di Croce, Davide; Janssen, Xavier; Lauwers, Jasper; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; De Bruyn, Isabelle; De Clercq, Jarne; Deroover, Kevin; Flouris, Giannis; Lontkovskyi, Denys; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; 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Margaroli, Fabrizio; Marzocchi, Badder; Meridiani, Paolo; Organtini, Giovanni; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Monteno, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Ravera, Fabio; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Traczyk, Piotr; Belforte, Stefano; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Jeongeun; Lee, Sangeun; Lee, Seh Wook; Moon, Chang-Seong; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Lee, Ari; Kim, Hyunchul; Moon, Dong Ho; Oh, Geonhee; Brochero Cifuentes, Javier Andres; Goh, Junghwan; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Kim, Yongsun; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Almond, John; Kim, Junho; Kim, Jae Sung; Lee, Haneol; Lee, Kyeongpil; Nam, Kyungwook; Oh, Sung Bin; Radburn-Smith, Benjamin Charles; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Choi, Minkyoo; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Ryu, Geonmo; Choi, Young-Il; Hwang, Chanwook; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-De La Cruz, Ivan; Lopez-Fernandez, Ricardo; Mejia Guisao, Jhovanny; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Saddique, Asif; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bozena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Pyskir, Andrzej; Walczak, Marek; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Calpas, Betty; Di Francesco, Agostino; Faccioli, Pietro; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nemallapudi, Mythra Varun; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Gorbunov, Ilya; Kamenev, Alexey; Karjavin, Vladimir; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Voytishin, Nikolay; Zarubin, Anatoli; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Stepennov, Anton; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Aushev, Tagir; Bylinkin, Alexander; Chistov, Ruslan; Danilov, Mikhail; Parygin, Pavel; Philippov, Dmitry; Polikarpov, Sergey; Tarkovskii, Evgenii; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Lokhtin, Igor; Miagkov, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Blinov, Vladimir; Skovpen, Yuri; Shtol, Dmitry; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Dordevic, Milos; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Barrio Luna, Mar; Cerrada, Marcos; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Álvarez Fernández, Adrian; de Trocóniz, Jorge F; Missiroli, Marino; Moran, Dermot; Cuevas, Javier; Erice, Carlos; Fernandez Menendez, Javier; Gonzalez Caballero, Isidro; González Fernández, Juan Rodrigo; Palencia Cortezon, Enrique; Sanchez Cruz, Sergio; Suárez Andrés, Ignacio; Vischia, Pietro; Vizan Garcia, Jesus Manuel; Cabrillo, Iban Jose; Calderon, Alicia; Chazin Quero, Barbara; Curras, Esteban; Fernandez, Marcos; Garcia-Ferrero, Juan; Gomez, Gervasio; Lopez Virto, Amparo; Marco, Jesus; Martinez Rivero, Celso; Martinez Ruiz del Arbol, Pablo; Matorras, Francisco; Piedra Gomez, Jonatan; Rodrigo, Teresa; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Trevisani, Nicolò; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Baillon, Paul; Ball, Austin; Barney, David; Bianco, Michele; Bloch, Philippe; Bocci, Andrea; Botta, Cristina; Camporesi, Tiziano; Castello, Roberto; Cepeda, Maria; Cerminara, Gianluca; Chapon, Emilien; Chen, Yi; D'Enterria, David; Dabrowski, Anne; Daponte, Vincenzo; David Tinoco Mendes, Andre; De Gruttola, Michele; De Roeck, Albert; Di Marco, Emanuele; Dobson, Marc; Dorney, Brian; Du Pree, Tristan; Dünser, Marc; Dupont, Niels; Elliott-Peisert, Anna; Everaerts, Pieter; Franzoni, Giovanni; Fulcher, Jonathan; Funk, Wolfgang; Gigi, Dominique; Gill, Karl; Glege, Frank; Gulhan, Doga; Gundacker, Stefan; Guthoff, Moritz; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Karacheban, Olena; Kieseler, Jan; Kirschenmann, Henning; Knünz, Valentin; Kornmayer, Andreas; Kortelainen, Matti J; Krammer, Manfred; Lange, Clemens; Lecoq, Paul; Lourenco, Carlos; Lucchini, Marco Toliman; Malgeri, Luca; Mannelli, Marcello; Martelli, Arabella; Meijers, Frans; Merlin, Jeremie Alexandre; Mersi, Stefano; Meschi, Emilio; Milenovic, Predrag; Moortgat, Filip; Mulders, Martijn; Neugebauer, Hannes; Orfanelli, Styliani; Orsini, Luciano; Pape, Luc; Perez, Emmanuel; Peruzzi, Marco; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Racz, Attila; Reis, Thomas; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Seidel, Markus; Selvaggi, Michele; Sharma, Archana; Silva, Pedro; Sphicas, Paraskevas; Steggemann, Jan; Stoye, Markus; Tosi, Mia; Treille, Daniel; Triossi, Andrea; Tsirou, Andromachi; Veckalns, Viesturs; Veres, Gabor Istvan; Verweij, Marta; Wardle, Nicholas; Zeuner, Wolfram Dietrich; Bertl, Willi; Caminada, Lea; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Rohe, Tilman; Wiederkehr, Stephan Albert; Bachmair, Felix; Bäni, Lukas; Berger, Pirmin; Bianchini, Lorenzo; Casal, Bruno; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Grab, Christoph; Heidegger, Constantin; Hits, Dmitry; Hoss, Jan; Kasieczka, Gregor; Klijnsma, Thomas; Lustermann, Werner; Mangano, Boris; Marionneau, Matthieu; Meinhard, Maren Tabea; Meister, Daniel; Micheli, Francesco; Musella, Pasquale; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pata, Joosep; Pauss, Felicitas; Perrin, Gaël; Perrozzi, Luca; Quittnat, Milena; Schönenberger, Myriam; Shchutska, Lesya; Tavolaro, Vittorio Raoul; Theofilatos, Konstantinos; Vesterbacka Olsson, Minna Leonora; Wallny, Rainer; Zagozdzinska, Agnieszka; Zhu, De Hua; Aarrestad, Thea Klaeboe; Amsler, Claude; Canelli, Maria Florencia; De Cosa, Annapaola; Donato, Silvio; Galloni, Camilla; Hreus, Tomas; Kilminster, Benjamin; Ngadiuba, Jennifer; Pinna, Deborah; Rauco, Giorgia; Robmann, Peter; Salerno, Daniel; Seitz, Claudia; Zucchetta, Alberto; Candelise, Vieri; Doan, Thi Hien; Jain, Shilpi; Khurana, Raman; Kuo, Chia-Ming; Lin, Willis; Pozdnyakov, Andrey; Yu, Shin-Shan; Kumar, Arun; Chang, Paoti; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Fiori, Francesco; Hou, George Wei-Shu; Hsiung, Yee; Liu, Yueh-Feng; Lu, Rong-Shyang; Miñano Moya, Mercedes; Paganis, Efstathios; Psallidas, Andreas; Tsai, Jui-fa; Asavapibhop, Burin; Kovitanggoon, Kittikul; Singh, Gurpreet; Srimanobhas, Norraphat; Adiguzel, Aytul; Boran, Fatma; Cerci, Salim; Damarseckin, Serdal; Demiroglu, Zuhal Seyma; Dozen, Candan; Dumanoglu, Isa; Girgis, Semiray; Gokbulut, Gul; Guler, Yalcin; Hos, Ilknur; Kangal, Evrim Ersin; Kara, Ozgun; Kayis Topaksu, Aysel; Kiminsu, Ugur; Oglakci, Mehmet; Onengut, Gulsen; Ozdemir, Kadri; Sunar Cerci, Deniz; Tali, Bayram; Turkcapar, Semra; Zorbakir, Ibrahim Soner; Zorbilmez, Caglar; Bilin, Bugra; Karapinar, Guler; Ocalan, Kadir; Yalvac, Metin; Zeyrek, Mehmet; Gülmez, Erhan; Kaya, Mithat; Kaya, Ozlem; Tekten, Sevgi; Yetkin, Elif Asli; Nazlim Agaras, Merve; Atay, Serhat; Cakir, Altan; Cankocak, Kerem; Grynyov, Boris; Levchuk, Leonid; Sorokin, Pavel; Aggleton, Robin; Ball, Fionn; Beck, Lana; Brooke, James John; Burns, Douglas; Clement, Emyr; Cussans, David; Davignon, Olivier; Flacher, Henning; Goldstein, Joel; Grimes, Mark; Heath, Greg P; Heath, Helen F; Jacob, Jeson; Kreczko, Lukasz; Lucas, Chris; Newbold, Dave M; Paramesvaran, Sudarshan; Poll, Anthony; Sakuma, Tai; Seif El Nasr-storey, Sarah; Smith, Dominic; Smith, Vincent J; Bell, Ken W; Belyaev, Alexander; Brew, Christopher; Brown, Robert M; Calligaris, Luigi; Cieri, Davide; Cockerill, David JA; Coughlan, John A; Harder, Kristian; Harper, Sam; Olaiya, Emmanuel; Petyt, David; Shepherd-Themistocleous, Claire; Thea, Alessandro; Tomalin, Ian R; Williams, Thomas; Bainbridge, Robert; Breeze, Shane; Buchmuller, Oliver; Bundock, Aaron; Casasso, Stefano; Citron, Matthew; Colling, David; Corpe, Louie; Dauncey, Paul; Davies, Gavin; De Wit, Adinda; Della Negra, Michel; Di Maria, Riccardo; Elwood, Adam; Haddad, Yacine; Hall, Geoffrey; Iles, Gregory; James, Thomas; Lane, Rebecca; Laner, Christian; Lyons, Louis; Magnan, Anne-Marie; Malik, Sarah; Mastrolorenzo, Luca; Matsushita, Takashi; Nash, Jordan; Nikitenko, Alexander; Palladino, Vito; Pesaresi, Mark; Raymond, David Mark; Richards, Alexander; Rose, Andrew; Scott, Edward; Seez, Christopher; Shtipliyski, Antoni; Summers, Sioni; Tapper, Alexander; Uchida, Kirika; Vazquez Acosta, Monica; Virdee, Tejinder; Winterbottom, Daniel; Wright, Jack; Zenz, Seth Conrad; Cole, Joanne; Hobson, Peter R; Khan, Akram; Kyberd, Paul; Reid, Ivan; Symonds, Philip; Teodorescu, Liliana; Turner, Mark; Borzou, Ahmad; Call, Kenneth; Dittmann, Jay; Hatakeyama, Kenichi; Liu, Hongxuan; Pastika, Nathaniel; Smith, Caleb; Bartek, Rachel; Dominguez, Aaron; Buccilli, Andrew; Cooper, Seth; Henderson, Conor; Rumerio, Paolo; West, Christopher; Arcaro, Daniel; Avetisyan, Aram; Bose, Tulika; Gastler, Daniel; Rankin, Dylan; Richardson, Clint; Rohlf, James; Sulak, Lawrence; Zou, David; Benelli, Gabriele; Cutts, David; Garabedian, Alex; Hakala, John; Heintz, Ulrich; Hogan, Julie Managan; Kwok, Ka Hei Martin; Laird, Edward; Landsberg, Greg; Mao, Zaixing; Narain, Meenakshi; Pazzini, Jacopo; Piperov, Stefan; Sagir, Sinan; Syarif, Rizki; Yu, David; Band, Reyer; Brainerd, Christopher; Burns, Dustin; Calderon De La Barca Sanchez, Manuel; Chertok, Maxwell; Conway, John; Conway, Rylan; Cox, Peter Timothy; Erbacher, Robin; Flores, Chad; Funk, Garrett; Gardner, Michael; Ko, Winston; Lander, Richard; Mclean, Christine; Mulhearn, Michael; Pellett, Dave; Pilot, Justin; Shalhout, Shalhout; Shi, Mengyao; Smith, John; Squires, Michael; Stolp, Dustin; Tos, Kyle; Tripathi, Mani; Wang, Zhangqier; Bachtis, Michail; Bravo, Cameron; Cousins, Robert; Dasgupta, Abhigyan; Florent, Alice; Hauser, Jay; Ignatenko, Mikhail; Mccoll, Nickolas; Saltzberg, David; Schnaible, Christian; Valuev, Vyacheslav; Bouvier, Elvire; Burt, Kira; Clare, Robert; Ellison, John Anthony; Gary, J William; Ghiasi Shirazi, Seyyed Mohammad Amin; Hanson, Gail; Heilman, Jesse; Jandir, Pawandeep; Kennedy, Elizabeth; Lacroix, Florent; Long, Owen Rosser; Olmedo Negrete, Manuel; Paneva, Mirena Ivova; Shrinivas, Amithabh; Si, Weinan; Wang, Long; Wei, Hua; Wimpenny, Stephen; Yates, Brent; Branson, James G; Cittolin, Sergio; Derdzinski, Mark; Hashemi, Bobak; Holzner, André; Klein, Daniel; Kole, Gouranga; Krutelyov, Vyacheslav; Letts, James; Macneill, Ian; Masciovecchio, Mario; Olivito, Dominick; Padhi, Sanjay; Pieri, Marco; Sani, Matteo; Sharma, Vivek; Simon, Sean; Tadel, Matevz; Vartak, Adish; Wasserbaech, Steven; Wood, John; Würthwein, Frank; Yagil, Avraham; Zevi Della Porta, Giovanni; Amin, Nick; Bhandari, Rohan; Bradmiller-Feld, John; Campagnari, Claudio; Dishaw, Adam; Dutta, Valentina; Franco Sevilla, Manuel; George, Christopher; Golf, Frank; Gouskos, Loukas; Gran, Jason; Heller, Ryan; Incandela, Joe; Mullin, Sam Daniel; Ovcharova, Ana; Qu, Huilin; Richman, Jeffrey; Stuart, David; Suarez, Indara; Yoo, Jaehyeok; Anderson, Dustin; Bendavid, Joshua; Bornheim, Adolf; Lawhorn, Jay Mathew; Newman, Harvey B; Nguyen, Thong; Pena, Cristian; Spiropulu, Maria; Vlimant, Jean-Roch; Xie, Si; Zhang, Zhicai; Zhu, Ren-Yuan; Andrews, Michael Benjamin; Ferguson, Thomas; Mudholkar, Tanmay; Paulini, Manfred; Russ, James; Sun, Menglei; Vogel, Helmut; Vorobiev, Igor; Weinberg, Marc; Cumalat, John Perry; Ford, William T; Jensen, Frank; Johnson, Andrew; Krohn, Michael; Leontsinis, Stefanos; Mulholland, Troy; Stenson, Kevin; Wagner, Stephen Robert; Alexander, James; Chaves, Jorge; Chu, Jennifer; Dittmer, Susan; Mcdermott, Kevin; Mirman, Nathan; Patterson, Juliet Ritchie; Rinkevicius, Aurelijus; Ryd, Anders; Skinnari, Louise; Soffi, Livia; Tan, Shao Min; Tao, Zhengcheng; Thom, Julia; Tucker, Jordan; Wittich, Peter; Zientek, Margaret; Abdullin, Salavat; Albrow, Michael; Apollinari, Giorgio; Apresyan, Artur; Apyan, Aram; Banerjee, Sunanda; Bauerdick, Lothar AT; Beretvas, Andrew; Berryhill, Jeffrey; Bhat, Pushpalatha C; Bolla, Gino; Burkett, Kevin; Butler, Joel Nathan; Canepa, Anadi; Cerati, Giuseppe Benedetto; Cheung, Harry; Chlebana, Frank; Cremonesi, Matteo; Duarte, Javier; Elvira, Victor Daniel; Freeman, Jim; Gecse, Zoltan; Gottschalk, Erik; Gray, Lindsey; Green, Dan; Grünendahl, Stefan; Gutsche, Oliver; Harris, Robert M; Hasegawa, Satoshi; Hirschauer, James; Hu, Zhen; Jayatilaka, Bodhitha; Jindariani, Sergo; Johnson, Marvin; Joshi, Umesh; Klima, Boaz; Kreis, Benjamin; Lammel, Stephan; Lincoln, Don; Lipton, Ron; Liu, Miaoyuan; Liu, Tiehui; Lopes De Sá, Rafael; Lykken, Joseph; Maeshima, Kaori; Magini, Nicolo; Marraffino, John Michael; Maruyama, Sho; Mason, David; McBride, Patricia; Merkel, Petra; Mrenna, Stephen; Nahn, Steve; O'Dell, Vivian; Pedro, Kevin; Prokofyev, Oleg; Rakness, Gregory; Ristori, Luciano; Schneider, Basil; Sexton-Kennedy, Elizabeth; Soha, Aron; Spalding, William J; Spiegel, Leonard; Stoynev, Stoyan; Strait, James; Strobbe, Nadja; Taylor, Lucas; Tkaczyk, Slawek; Tran, Nhan Viet; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vernieri, Caterina; Verzocchi, Marco; Vidal, Richard; Wang, Michael; Weber, Hannsjoerg Artur; Whitbeck, Andrew; Acosta, Darin; Avery, Paul; Bortignon, Pierluigi; Bourilkov, Dimitri; Brinkerhoff, Andrew; Carnes, Andrew; Carver, Matthew; Curry, David; Das, Souvik; Field, Richard D; Furic, Ivan-Kresimir; Konigsberg, Jacobo; Korytov, Andrey; Kotov, Khristian; Ma, Peisen; Matchev, Konstantin; Mei, Hualin; Mitselmakher, Guenakh; Rank, Douglas; Sperka, David; Terentyev, Nikolay; Thomas, Laurent; Wang, Jian; Wang, Sean-Jiun; Yelton, John; Joshi, Yagya Raj; Linn, Stephan; Markowitz, Pete; Rodriguez, Jorge Luis; Ackert, Andrew; Adams, Todd; Askew, Andrew; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Kolberg, Ted; Martinez, German; Perry, Thomas; Prosper, Harrison; Saha, Anirban; Santra, Arka; Yohay, Rachel; Baarmand, Marc M; Bhopatkar, Vallary; Colafranceschi, Stefano; Hohlmann, Marcus; Noonan, Daniel; Roy, Titas; Yumiceva, Francisco; Adams, Mark Raymond; Apanasevich, Leonard; Berry, Douglas; Betts, Russell Richard; Cavanaugh, Richard; Chen, Xuan; Evdokimov, Olga; Gerber, Cecilia Elena; Hangal, Dhanush Anil; Hofman, David Jonathan; Jung, Kurt; Kamin, Jason; Sandoval Gonzalez, Irving Daniel; Tonjes, Marguerite; Trauger, Hallie; Varelas, Nikos; Wang, Hui; Wu, Zhenbin; Zhang, Jingyu; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Durgut, Süleyman; Gandrajula, Reddy Pratap; Haytmyradov, Maksat; Khristenko, Viktor; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Snyder, Christina; Tiras, Emrah; Wetzel, James; Yi, Kai; Blumenfeld, Barry; Cocoros, Alice; Eminizer, Nicholas; Fehling, David; Feng, Lei; Gritsan, Andrei; Maksimovic, Petar; Roskes, Jeffrey; Sarica, Ulascan; Swartz, Morris; Xiao, Meng; You, Can; Al-bataineh, Ayman; Baringer, Philip; Bean, Alice; Boren, Samuel; Bowen, James; Castle, James; Khalil, Sadia; Kropivnitskaya, Anna; Majumder, Devdatta; Mcbrayer, William; Murray, Michael; Royon, Christophe; Sanders, Stephen; Schmitz, Erich; Stringer, Robert; Tapia Takaki, Daniel; Wang, Quan; Ivanov, Andrew; Kaadze, Ketino; Maravin, Yurii; Mohammadi, Abdollah; Saini, Lovedeep Kaur; Skhirtladze, Nikoloz; Toda, Sachiko; Rebassoo, Finn; Wright, Douglas; Anelli, Christopher; Baden, Drew; Baron, Owen; Belloni, Alberto; Calvert, Brian; Eno, Sarah Catherine; Ferraioli, Charles; Hadley, Nicholas John; Jabeen, Shabnam; Jeng, Geng-Yuan; Kellogg, Richard G; Kunkle, Joshua; Mignerey, Alice; Ricci-Tam, Francesca; Shin, Young Ho; Skuja, Andris; Tonwar, Suresh C; Abercrombie, Daniel; Allen, Brandon; Azzolini, Virginia; Barbieri, Richard; Baty, Austin; Bi, Ran; Brandt, Stephanie; Busza, Wit; Cali, Ivan Amos; D'Alfonso, Mariarosaria; Demiragli, Zeynep; Gomez Ceballos, Guillelmo; Goncharov, Maxim; Hsu, Dylan; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew; Luckey, Paul David; Maier, Benedikt; Marini, Andrea Carlo; Mcginn, Christopher; Mironov, Camelia; Narayanan, Siddharth; Niu, Xinmei; Paus, Christoph; Roland, Christof; Roland, Gunther; Salfeld-Nebgen, Jakob; Stephans, George; Tatar, Kaya; Velicanu, Dragos; Wang, Jing; Wang, Ta-Wei; Wyslouch, Bolek; Benvenuti, Alberto; Chatterjee, Rajdeep Mohan; Evans, Andrew; Hansen, Peter; Kalafut, Sean; Kubota, Yuichi; Lesko, Zachary; Mans, Jeremy; Nourbakhsh, Shervin; Ruckstuhl, Nicole; Rusack, Roger; Turkewitz, Jared; Acosta, John Gabriel; Oliveros, Sandra; Avdeeva, Ekaterina; Bloom, Kenneth; Claes, Daniel R; Fangmeier, Caleb; Gonzalez Suarez, Rebeca; Kamalieddin, Rami; Kravchenko, Ilya; Monroy, Jose; Siado, Joaquin Emilo; Snow, Gregory R; Stieger, Benjamin; Alyari, Maral; Dolen, James; Godshalk, Andrew; Harrington, Charles; Iashvili, Ia; Nguyen, Duong; Parker, Ashley; Rappoccio, Salvatore; Roozbahani, Bahareh; Alverson, George; Barberis, Emanuela; Hortiangtham, Apichart; Massironi, Andrea; Morse, David Michael; Nash, David; Orimoto, Toyoko; Teixeira De Lima, Rafael; Trocino, Daniele; Wood, Darien; Bhattacharya, Saptaparna; Charaf, Otman; Hahn, Kristan Allan; Mucia, Nicholas; Odell, Nathaniel; Pollack, Brian; Schmitt, Michael Henry; Sung, Kevin; Trovato, Marco; Velasco, Mayda; Dev, Nabarun; Hildreth, Michael; Hurtado Anampa, Kenyi; Jessop, Colin; Karmgard, Daniel John; Kellams, Nathan; Lannon, Kevin; Loukas, Nikitas; Marinelli, Nancy; Meng, Fanbo; Mueller, Charles; Musienko, Yuri; Planer, Michael; Reinsvold, Allison; Ruchti, Randy; Smith, Geoffrey; Taroni, Silvia; Wayne, Mitchell; Wolf, Matthias; Woodard, Anna; Alimena, Juliette; Antonelli, Louis; Bylsma, Ben; Durkin, Lloyd Stanley; Flowers, Sean; Francis, Brian; Hart, Andrew; Hill, Christopher; Ji, Weifeng; Liu, Bingxuan; Luo, Wuming; Puigh, Darren; Winer, Brian L; Wulsin, Howard Wells; Benaglia, Andrea; Cooperstein, Stephane; Driga, Olga; Elmer, Peter; Hardenbrook, Joshua; Hebda, Philip; Higginbotham, Samuel; Lange, David; Luo, Jingyu; Marlow, Daniel; Mei, Kelvin; Ojalvo, Isabel; Olsen, James; Palmer, Christopher; Piroué, Pierre; Stickland, David; Tully, Christopher; Malik, Sudhir; Norberg, Scarlet; 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2018-03-10

Results are presented from a search for the pair production of third-generation squarks in proton-proton collision events with two-body decays to bottom or charm quarks and a neutralino, which produces a significant imbalance in the transverse momentum. The search is performed using a sample of proton-proton collision data at $ \\sqrt{s} = $ 13 TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No statistically significant excess of events is observed beyond the expected contribution from standard model processes. Exclusion limits are set in the context of simplified models of bottom or top squark pair production. Models with bottom squark masses up to 1220 GeV are excluded at 95% confidence level for light neutralinos, and models with top squark masses of 510 GeV are excluded assuming that the mass splitting between the top squark and the neutralino is small.

Search for the pair production of third-generation squarks with two-body decays to a bottom or charm quark and a neutralino in proton-proton collisions at √{ s } = 13TeV

Science.gov (United States)

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P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Álvarez Fernández, A.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Cuevas, J.; Erice, C.; Fernandez Menendez, J.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Suárez Andrés, I.; Vischia, P.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Chazin Quero, B.; Curras, E.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Martinez Ruiz del Arbol, P.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Baillon, P.; Ball, A. H.; Barney, D.; Bianco, M.; Bloch, P.; Bocci, A.; Botta, C.; Camporesi, T.; Castello, R.; Cepeda, M.; Cerminara, G.; Chapon, E.; Chen, Y.; d'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; De Gruttola, M.; De Roeck, A.; Di Marco, E.; Dobson, M.; Dorney, B.; du Pree, T.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Everaerts, P.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gill, K.; Glege, F.; Gulhan, D.; Gundacker, S.; Guthoff, M.; Harris, P.; Hegeman, J.; Innocente, V.; Janot, P.; Karacheban, O.; Kieseler, J.; Kirschenmann, H.; Knünz, V.; Kornmayer, A.; Kortelainen, M. J.; Krammer, M.; Lange, C.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Malgeri, L.; Mannelli, M.; Martelli, A.; Meijers, F.; Merlin, J. A.; Mersi, S.; Meschi, E.; Milenovic, P.; Moortgat, F.; Mulders, M.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Sakulin, H.; Schäfer, C.; Schwick, C.; Seidel, M.; Selvaggi, M.; Sharma, A.; Silva, P.; Sphicas, P.; Steggemann, J.; Stoye, M.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Veres, G. I.; Verweij, M.; Wardle, N.; Zeuner, W. D.; Bertl, W.; Caminada, L.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Wiederkehr, S. A.; Bachmair, F.; Bäni, L.; Berger, P.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Klijnsma, T.; Lustermann, W.; Mangano, B.; Marionneau, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Schönenberger, M.; Shchutska, L.; Tavolaro, V. R.; Theofilatos, K.; Vesterbacka Olsson, M. L.; Wallny, R.; Zagozdzinska, A.; Zhu, D. H.; Aarrestad, T. K.; Amsler, C.; Canelli, M. F.; De Cosa, A.; Donato, S.; Galloni, C.; Hreus, T.; Kilminster, B.; Ngadiuba, J.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Seitz, C.; Zucchetta, A.; Candelise, V.; Doan, T. H.; Jain, Sh.; Khurana, R.; Kuo, C. M.; Lin, W.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chao, Y.; Chen, K. F.; Chen, P. H.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Paganis, E.; Psallidas, A.; Tsai, J. f.; Asavapibhop, B.; Kovitanggoon, K.; Singh, G.; Srimanobhas, N.; Adiguzel, A.; Boran, F.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. E.; Kara, O.; Kayis Topaksu, A.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Sunar Cerci, D.; Tali, B.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Bilin, B.; Karapinar, G.; Ocalan, K.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Tekten, S.; Yetkin, E. A.; Agaras, M. N.; Atay, S.; Cakir, A.; Cankocak, K.; Grynyov, B.; Levchuk, L.; Sorokin, P.; Aggleton, R.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Davignon, O.; Flacher, H.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Jacob, J.; Kreczko, L.; Lucas, C.; Newbold, D. M.; Paramesvaran, S.; Poll, A.; Sakuma, T.; Seif El Nasr-storey, S.; Smith, D.; Smith, V. J.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Calligaris, L.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Bainbridge, R.; Breeze, S.; Buchmuller, O.; Bundock, A.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Elwood, A.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Matsushita, T.; Nash, J.; Nikitenko, A.; Palladino, V.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Shtipliyski, A.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Winterbottom, D.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Smith, C.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. 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.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Martinez, G.; 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.; 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.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Brodski, M.; 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

2018-03-01

Results are presented from a search for the pair production of third-generation squarks in proton-proton collision events with two-body decays to bottom or charm quarks and a neutralino, which produces a significant imbalance in the transverse momentum. The search is performed using a sample of proton-proton collision data at √{ s } = 13TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb-1. No statistically significant excess of events is observed beyond the expected contribution from standard model processes. Exclusion limits are set in the context of simplified models of bottom or top squark pair production. Models with bottom squark masses up to 1220 GeV are excluded at 95% confidence level for light neutralinos, and models with top squark masses of 510 GeV are excluded assuming that the mass splitting between the top squark and the neutralino is small.

Cost-Effective Icy Bodies Exploration using Small Satellite Missions

Science.gov (United States)

Jonsson, Jonas; Mauro, David; Stupl, Jan; Nayak, Michael; Aziz, Jonathan; Cohen, Aaron; Colaprete, Anthony; Dono-Perez, Andres; Frost, Chad; Klamm, Benjamin;

Results from proton–lead collisions

CERN Document Server

Mischke, André

2016-01-01

This contribution summarises recent measurements in small collision systems at the Large Hadron Collider (LHC), presented at the 2016 edition of the Annual Large Hadron Collider Physics conference. Three main probes are discussed, namely light flavour (strangeness) production, az- imuthal angular correlations and jets, and open and hidden heavy-flavour production in proton- lead collisions.

Collision of a Small Rising Bubble with a Large Falling Particle

Czech Academy of Sciences Publication Activity Database

Hubička, M.; Basařová, P.; Vejražka, Jiří

2013-01-01

Roč. 121, JUN 10 (2013), s. 21-30 ISSN 0301-7516 R&D Projects: GA ČR GAP101/11/0806 Grant - others:GA MŠk(CZ) 21/2011 Institutional support: RVO:67985858 Keywords : bubble-particle interaction * collision process * collision efficiency Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.461, year: 2013

Small solar system bodies as granular systems

Science.gov (United States)

Hestroffer, Daniel; Campo Bagatín, Adriano; Losert, Wolfgang; Opsomer, Eric; Sánchez, Paul; Scheeres, Daniel J.; Staron, Lydie; Taberlet, Nicolas; Yano, Hajime; Eggl, Siegfried; Lecomte, Charles-Edouard; Murdoch, Naomi; Radjai, Fahrang; Richardson, Derek C.; Salazar, Marcos; Schwartz, Stephen R.; Tanga, Paolo

2017-06-01

Asteroids and other Small Solar System Bodies (SSSBs) are currently of great scientific and even industrial interest. Asteroids exist as the permanent record of the formation of the Solar System and therefore hold many clues to its understanding as a whole, as well as insights into the formation of planetary bodies. Additionally, SSSBs are being investigated in the context of impact risks for the Earth, space situational awareness and their possible industrial exploitation (asteroid mining). In all these aspects, the knowledge of the geophysical characteristics of SSSB surface and internal structure are of great importance. Given their size, constitution, and the evidence that many SSSBs are not simple monoliths, these bodies should be studied and modelled as self-gravitating granular systems in general, or as granular systems in micro-gravity environments in particular contexts. As such, the study of the geophysical characteristics of SSSBs is a multi-disciplinary effort that lies at the crossroads between Granular Mechanics, Celestial Mechanics, Soil Mechanics, Aerospace Engineering and Computer Sciences.

Anchoring Technology for In Situ Exploration of Small Bodie

Science.gov (United States)

Steltzner, A.; Nasif, A.

2000-01-01

Comets, asteroids and other small bodies found in the solar system do not possess enough gravity to ensure spacecraft contact forces sufficient to allow many types of in situ science, such as core or surface sampling.

Two- and Multi-particle Azimuthal Correlations in Small Collision Systems with the ATLAS Detector

CERN Document Server

Trzupek, Adam; The ATLAS collaboration

2017-01-01

ATLAS measurements of two-particle correlations in $\\Delta\\phi$ and $\\Delta\\eta$ are presented for $pp$ collisions at 2.76, 5.02 and 13~TeV, and for $p$+Pb collisions at 5.02 TeV. A template fitting procedure is used to subtract the dijet contribution and to extract the genuine long-range ridge correlations. This template procedure was previously used for 2.76 TeV and 13 TeV pp collisions, but is now extended to pp and $p$+Pb collisions at 5.02 TeV. In all collision systems, the ridge correlations are shown to be present even in events with a low multiplicity of produced particles, implying that the long-range correlations are not unique to rare high-multiplicity events. The properties of the correlation are shown to exhibit only a weak energy dependence and are remarkably similar to that observed in $p$+Pb collisions. Another new aspect of this talk is a detailed study of ridge properties in collisions containing hard processes, characterized by large four-momentum transfer. This may help answering the quest...

Macroscopic and microscopic description of HE-HI collisions; classical equations of motion calculations. [Rapidity, cross sections, central and noncentral collisions

Energy Technology Data Exchange (ETDEWEB)

Bodmer, A. R.

1978-01-01

The study of high energy heavy ion reactions includes the three principle a priori approaches used for central collisions, namely, hydrodynamics, cascade--Boltzman equation, and the classical equations of motion. While no clearly justified central or near central collisions are found, the classical equations of motion are used to illustrate some general features of these reactions. It is expected that the hot nuclear matter produced in such collisions is a dense, viscous, and thermally conductive fluid with important nonequilibrium and nonclassical features, rapidity, distribution, noncentral collisions, potential dependent effects for a given two-body scattering, and c.m. cross sections for a central collision with given parameters are among the properties considered. 12 references. (JFP)

Intercellular cancer collisions generate an ejected crystal comet tail effect with fractal interface embryoid body reassembly transformation

Directory of Open Access Journals (Sweden)

Díaz JA

2011-05-01

Full Text Available Jairo A Díaz, Mauricio F Murillo, Alvaro BarreroDepartment of Pathology, Hospital Departmental Villavicencio, Hospital Departmental Granada, Medicine School, University Cooperative of Colombia, Villavicencio, Meta, ColombiaAbstract: We have documented self-assembled geometric triangular chiral crystal complexes (GTCHC and a framework of collagen vascular invariant geometric attractors in cancer tissues. This article shows how this system evolves in time. These structures are incorporated together and evolve in different ways. When the geometric core is stable, and the tissue architecture collapses, fragmented components emerge, which reveal a hidden interior identifying how each molecule is reassembled into the original mold, using one common connection, ie, a fractal self-similarity that guided the system from the beginning. GTCHC complexes generate ejected crystal comet tail effects and produce strange helicity states that arise in the form of spin domain interactions. As the crystal growth vibration stage progresses, biofractal echo images converge in a master-built construction of embryoid bodies with enolase-selective immunopositivity in relation to clusters of triangular chiral cell organization. In our electro-optic collision model, we were able to predict and replicate all the characteristics of this complex geometry that connects a physical phenomenon with the signal patterns that generate biologic chaos. Intrinsically, fractal geometry makes spatial correction errors embrace the chaotic system in a way that permits new structures to emerge, and as a result, an ordered self-assembly of embryoid bodies with neural differentiation at the final stage of cancer development is a predictable process. We hope that further investigation of these structures will lead not only to a new way of thinking about physics and biology, but also to a rewarding area in cancer research.Keywords: embryoid bodies, cancer, electro-optic collision model

Consequences of high-x proton size fluctuations in small collision systems at √{sNN}=200 GeV

Science.gov (United States)

McGlinchey, D.; Nagle, J. L.; Perepelitsa, D. V.

2016-08-01

Recent measurements of jet production rates at large transverse momentum (pT) in the collisions of small projectiles with large nuclei at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider indicate that they have an unexpected relationship with estimates of the collision centrality. One compelling interpretation of the data is that they capture an xp-dependent decrease in the average interaction strength of the nucleon in the projectile undergoing a hard scattering. A weakly interacting or "shrinking" nucleon in the projectile strikes fewer nucleons in the nucleus, resulting in a particular pattern of centrality-dependent modifications to high-pT processes. We describe a simple one-parameter geometric implementation of this picture within a modified Monte Carlo Glauber model tuned to d +Au jet data, and explore two of its major consequences. First, the model predicts a particular projectile-species effect on the centrality dependence at high xp, opposite to that expected from a final state energy loss effect. Second, we find that some of the large centrality dependence observed for forward dihadron production in d +Au collisions at RHIC may arise from the physics of the "shrinking" projectile nucleon, in addition to impact parameter dependent shadowing or saturation effects at low nuclear x . We conclude that analogous measurements in recently collected p +Au and 3He+Au collision data at RHIC can provide a unique test of these predictions.

Migration of Small Bodies and Dust to Near-Earth Space

Science.gov (United States)

Ipatov, S. I.; Mather, J. C.

Computer simulations of the orbital evolution of Jupiter-family comets (JFCs), resonant asteroids, and asteroidal, kuiperoidal, and cometary dust particles were made. The gravitational influence of planets (exclusive of Pluto and sometimes of Mercury) was taken into account. For dust particles we also considered radiation pressure, Poynting-Robertson drag, and solar wind drag. A few JFCs got Earth-crossing orbits with semi-major axes adisintegrated into mini-comets and dust during a smaller part of their dynamical lifetimes if these lifetimes are not small. The obtained results show that during the accumulation of the giant planets the total mass of icy bodies delivered to the Earth could be about the mass of water in Earth's oceans. In our runs for dust particles, the values of the ratio β between the radiation pressure force and the gravitational force varied from 0.0004 to 0.4 (for silicates, such values correspond to particle diameters between 1000 and 1 microns). For β >0.01 the collision probabilities of dust particles with the terrestrial planets during lifetimes of particles were considerably greater for larger asteroidal and cometary particles. At β ≥ 0.1 and β ≤ 0.001 some asteroidal particles migrated beyond Jupiter's orbit. The peaks in the distribution of migrating asteroidal dust particles with semi-major axis corresponding to the n:(n+1) resonances with Earth and Venus and the gaps associated with the 1:1 resonances with these planets are more pronounced for larger particles. Several our papers on this problem were put in http://arXiv.org/format/astro-ph/ (e.g., 0305519, 0308448, 0308450). This work was supported by INTAS (00-240) and NASA (NAG5-10776).

Investigation of Planets and Small Bodies Using Decameter Wavelength Radar Sounders

Science.gov (United States)

Safaeinili, A.

2003-12-01

Decameter wavelength radar sounders provide a unique capability for the exploration of subsurface of planets and internal structure of small bodies. Recently, a number of experimental radar sounding instruments have been proposed and/or are planned to become operational in the near future. The first of these radar sounders is MARSIS (Picardi et al.) that is about to arrive at Mars on ESA's Mars Express for a two-year mission. The second radar sounder, termed SHARAD (Seu et. al), will fly on NASA's Mars Reconnaissance orbiter in 2005. MARSIS and SHARAD have complementary science objectives in that MARSIS (0.1-5.5 MHz) is designed to explore the deep subsurface with a depth resolution of ˜100 m while SHARAD (15-25 MHz) focuses its investigation to near-surface (generation of radar sounders will benefit from high power and high data rate capability that is made available through the use of Nuclear Electric generators. An example of such high-capability mission is the Jovian Icy Moons Orbiter (JIMO) where, for example, the radar sounder can be used to explore beneath the icy surfaces of Europa in search of the ice/ocean interface. The decameter wave radar sounder is probably the only instrument that has the potential of providing an accurate estimate for the ocean depth. Another exciting and rewarding area of application for planetary radar sounding is the investigation of the deep interior of small bodies (asteroids and comets). The small size of asteroids and comets provides the opportunity to collect data in a manner that enables Radio Reflection Tomographic (RRT) reconstruction of the body in the same manner that a medical ultrasound probe can image the interior of our body. This paper provides an overview of current technical capabilities and challenges and the potential of radio sounders in the investigation of planets and small bodies.

Differentiation history of small bodies in the solar system: the howardite and mesosiderite meteorite parent bodies

International Nuclear Information System (INIS)

Mittlefehldt, D.W.

1978-01-01

Mesosiderites and howardites are regolith samples of differentiated asteroids. Instrumental neutron activation analysis (INAA) data on whole rock howardites and mesosiderite silicates show that the composition of howardites and mesosiderites are similar, and intermediate between those of eucrites and diogenites. The mesosiderites Mincy, Lowicz and Veramin show an enrichment in light REE and have an REE pattern that is qualitatively similar to that in terrestrial basalts thought to have been formed by small degrees of partial melting. Attempts to model the REE abundances in these mesosiderites indicates that they most likely formed by approx. 2 to 4% partial melting of a source containing low abundances of the rare earths. Since numerous properties separate mesosiderite silicates from howardites, it is clear that they are not samples of a well-mixed regolith from a single parent body. If regolith stirring is efficient on small parent bodies, then mesosiderites and howardites originated on separate parent bodies. Rare earth element patterns give evidence for remelting and fractional crystallization of preexisting cumulates and sequential melting episodes. The mesosiderites appear to contain a slightly greater abundance of diogenite-like material and certainly contain a greater abundance of large olivine clasts. These observations suggest that the mesosiderite parent body crust was more complexly fractionated than the howardite parent body crust. The latter appears to have been dominated by quenched basalt flows

CHARACTERIZATION OF WILD PIG VEHICLE COLLISIONS

Energy Technology Data Exchange (ETDEWEB)

Mayer, J; Paul E. Johns, P

2007-05-23

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 per 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.

Colliding bodies optimization extensions and applications

CERN Document Server

Kaveh, A

2015-01-01

This book presents and applies a novel efficient meta-heuristic optimization algorithm called Colliding Bodies Optimization (CBO) for various optimization problems. The first part of the book introduces the concepts and methods involved, while the second is devoted to the applications. Though optimal design of structures is the main topic, two chapters on optimal analysis and applications in constructional management are also included.  This algorithm is based on one-dimensional collisions between bodies, with each agent solution being considered as an object or body with mass. After a collision of two moving bodies with specified masses and velocities, these bodies again separate, with new velocities. This collision causes the agents to move toward better positions in the search space.  The main algorithm (CBO) is internally parameter independent, setting it apart from previously developed meta-heuristics. This algorithm is enhanced (ECBO) for more efficient applications in the optimal design of structures...

Proton-proton correlations at small relative momentum in neon-nucleus collisions at E/A=400 and 800 MeV

International Nuclear Information System (INIS)

Dupieux, P.; Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Fraysse, L.; Marroncle, J.; Montarou, G.; Parizet, M.J.; Qassoud, D.; Rahmani, A.; Fodor, Z.

1988-01-01

Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4π detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density of target mass and incident energy is also analysed. (orig.)

A Geology Sampling System for Small Bodies

Science.gov (United States)

Naids, Adam J.; Hood, Anthony D.; Abell, Paul; Graff, Trevor; Buffington, Jesse

2016-01-01

Human exploration of microgravity bodies is being investigated as a precursor to a Mars surface mission. Asteroids, comets, dwarf planets, and the moons of Mars all fall into this microgravity category and some are being discussed as potential mission targets. Obtaining geological samples for return to Earth will be a major objective for any mission to a small body. Currently, the knowledge base for geology sampling in microgravity is in its infancy. Humans interacting with non-engineered surfaces in microgravity environment pose unique challenges. In preparation for such missions a team at the NASA Johnson Space Center has been working to gain experience on how to safely obtain numerous sample types in such an environment. This paper describes the type of samples the science community is interested in, highlights notable prototype work, and discusses an integrated geology sampling solution.

Low velocity collisions of porous planetesimals in the early solar system

Science.gov (United States)

de Niem, D.; Kührt, E.; Hviid, S.; Davidsson, B.

2018-02-01

The ESA Rosetta mission has shown that Comet 67P/Churuymov-Gerasimenko is bi-lobed, has a high average porosity of around 70%, does not have internal cavities on size scales larger than 10 m, the lobes could have individual sets of onion shell-like layering, and the nucleus surface contains 100 m-scale cylindrical pits. It is currently debated whether these properties are consistent with high-velocity collisional evolution or if they necessarily are surviving signatures of low-velocity primordial accretion. We use an Eulerian hydrocode to study collisions between highly porous bodies of different sizes, material parameters and relative velocities with emphasis on 5-100 m/s to characterize the effects of collisions in terms of deformation, compaction, and heating. We find that accretion of 1 km cometesimals by 3 km nuclei at 13.5 m/s flattens and partially buries the cometesimal with ∼ 1% reduction of the bulk porosity. This structure locally becomes more dense but the global effect of compaction is minor, suggesting that low-velocity accretion does not lead to a 'bunch of grapes' structure with large internal cavities but a more homogeneous interior, consistent with Rosetta findings. The mild local compaction associated with accretion is potentially the origin of the observed nucleus layering. In 2D axially symmetric impacts hit-and-stick collisions of similarly-sized nuclei are possible at velocities up to 30 m/s where deformation becomes severe. The bulk porosity is reduced significantly, even at 30-50 m/s relative velocity. To avoid hit-and-run collisions the impact angle must be less than 35°-45° from the surface normal at 10 m/s, and even smaller at higher velocities. Impact heating is insignificant. We find that the small cross section of the 67P neck may require a ≤ 5 m/s impact, unless the cohesion exceeds 10 kPa. We conclude that bi-lobe nucleus formation is possible at velocities typically discussed in hierarchical growth scenarios. Impacts of a 7 m

Ultrarelativistic oscillon collisions

NARCIS (Netherlands)

Amin, M.A.; Banik, I.; Negreanu, C.; Yang, I.S.

2014-01-01

In this short paper we investigate the ultrarelativistic collisions of small amplitude oscillons in 1+1 dimensions. Using the amplitude of the oscillons and the inverse relativistic boost factor γ−1 as the perturbation variables, we analytically calculate the leading order spatial and temporal phase

Small systems – hydrodynamics

Energy Technology Data Exchange (ETDEWEB)

Bożek, Piotr, E-mail: piotr.bozek@fis.agh.edu.pl

2016-12-15

The scenario assuming a collective expansion stage in collisions of small systems, p-A, d-Au, and {sup 3}He-Au is discussed. A review of the observables predicted in relativistic hydrodynamic models in comparison with experimental data is presented, with arguments indicating the presence of collective expansion. The limits of applicability of the hydrodynamic model are addressed. We briefly indicate possible applications of the collective flow in small systems to study the space-time dynamics at very small scales in relativistic collisions.

Correlations in small systems with ALICE

CERN Document Server

Lakomov, Igor

2016-01-01

ALICE is dedicated to the study of the strongly interacting matter, the so-called Quark-Gluon Plasma (QGP), formed in heavy-ion collisions at the LHC. In addition, ALICE also actively participated in the pp and p–Pb collision programs. In particular, the measurements of the twoparticle azimuthal correlations in pp collisions at √ s = 7 TeV and in p–Pb collisions at √ sNN = 5.02 TeV have been performed by the ALICE Collaboration during Run I of the LHC. Similar long-range correlations in p–Pb and Pb–Pb collisions have been observed on the near and away side — also known as the double ridge. Further investigations showed the importance of the Multi-Parton Interactions (MPI) in high-multiplicity collisions in small systems. In this work the ALICE results on the correlations in small systems are presented including MPI measurements in pp collisions.

Section of Atomic Collisions

International Nuclear Information System (INIS)

Berenyi, D.; Biri, S.; Gulyas, L.; Juhasz, Z.; Kover, A.; Orban, A.; Palinkas, J.; Papp, T.; Racz, R.; Ricz, S.

2009-01-01

The Section of Atomic Collisions is a research unit with extended activity in the field of atomic and molecular physics. Starting from the study of atomic processes at the beamlines of nuclear physics accelerators in the seventies, our research community became one of the centers of fundamental research in Atomki. We also have a strong connection to materials sciences especially along the line of electron and ion spectroscopy methods. Our present activity covers a wide range of topics from atomic collision mechanisms of fundamental interest, to the complex interactions of electrons, ions, photons and antiparticles with atoms, molecules, surfaces, and specific nanostructures. In the last few years, an increasing fraction of our present topics has become relevant for applications, e.g., molecular collision studies for the radiation therapy methods of tumors, or ion-nanostructure interactions for the future construction of small ion-focusing elements. Our section belongs to the Division of Atomic Physics. The other unit of the Division is the Section of Electron Spectroscopy and Materials Sciences. There are traditionally good connections and a strong collaboration between the groups of the two sections in many fields. From the very beginning of our research work in atomic collisions, external collaborations were of vital importance for us. We regularly organize international workshops in the field of fast ion-atom collisions and related small conferences in Debrecen from 1981. Recently, we organized the Conference on Radiation Damage in Biomolecular Systems (RADAM 2008, Debrecen), and coorganized the Conference on Elementary Processes in Atomic Systems (CEPAS 2008, Cluj). We have access to several large scale facilities in Europe within the framework of formal and informal collaborations. The next themes are in this article: Forward electron emission from energetic atomic collisions; Positron-atom collisions; Photon-atom interactions; Interference effects in electron

Exploring small bodies in the outer solar system with stellar occultations

Science.gov (United States)

Elliot, Jim L.; Dunham, Edward W.; Olkin, C. B.

1995-01-01

Stellar occultation observations probe the atmospheric structure and extinction of outer solar system bodies with a spatial resolution of a few kilometers, and an airborne platform allows the observation of occultations by small bodies that are not visible from fixed telescopes. Results from occultations by Triton, Pluto, and Chiron observed with KAO are discussed, and future directions for this program are presented.

Coalescence collision of liquid drops I: Off-center collisions of equal-size drops

Directory of Open Access Journals (Sweden)

Alejandro Acevedo-Malavé

2011-09-01

Full Text Available The Smoothed Particle Hydrodynamics method (SPH is used here to model off-center collisions of equal-size liquid drops in a three-dimensional space. In this study the Weber number is calculated for several conditions of the droplets dynamics and the velocity vector fields formed inside the drops during the collision process are shown. For the permanent coalescence the evolution of the kinetic and internal energy is shown and also the approaching to equilibrium of the resulting drop. Depending of the Weber number three possible outcomes for the collision of droplets is obtained: permanent coalescence, flocculation and fragmentation. The fragmentation phenomena are modeled and the formation of small satellite drops can be seen. The ligament that is formed follows the “end pinching” mechanism and it is transformed into a flat structure.

The art of being small : brain-body size scaling in minute parasitic wasps

NARCIS (Netherlands)

Woude, van der Emma

2017-01-01

Haller’s rule states that small animals have relatively larger brains than large animals. This brain-body size relationship may enable small animals to maintain similar levels of brain performance as large animals. However, it also causes small animals to spend an exceptionally large proportion

Small metal soft tissue foreign body extraction by using 3D CT guidance: A reliable method

International Nuclear Information System (INIS)

Tao, Kai; Xu, Sen; Liu, Xiao-yan; Liang, Jiu-long; Qiu, Tao; Tan, Jia-nan; Che, Jian-hua; Wang, Zi-hua

2012-01-01

Objective: To introduce a useful and accurate technique for the locating and removal of small metal foreign bodies in the soft tissues. Methods: Eight patients presented with suspected small metal foreign bodies retained in the soft tissues of various body districts. Under local anesthesia, 3–6 pieces of 5 ml syringe needles or 1 ml syringe needles were induced through three different planes around the entry point of the foreign bodies. Using these finders, the small metal FBs were confirmed under 3D CT guidance. Based on the CT findings, the soft tissues were dissected along the path of the closest needle and the FBs were easily found and removed according to the relation with the closest needle finder. Results: Eight metal foreign bodies (3 slices, 3 nails, 1 fish hook, 1 needlepoint) were successfully removed under 3D CT guidance in all patients. The procedures took between 35 min and 50 min and the operation times took between 15 min and 25 min. No complications arose after the treatment. Conclusion: 3D CT-guided technique is a good alternative for the removal of small metal foreign body retained in the soft tissues as it is relatively accurate, reliable, quick, carries a low risk of complications and can be a first-choice procedure for the extraction of small metal foreign body.

Phenotype characterization of embryoid body structures generated by a crystal comet effect tail in an intercellular cancer collision scenario

Directory of Open Access Journals (Sweden)

Diaz JA

2012-01-01

Full Text Available Jairo A Diaz, Mauricio F MurilloDepartment of Pathology, Hospital Departmental Villavicencio, Hospital Departmental Granada, Medicine School, University Cooperative of Colombia, Villavicencio, Meta, ColombiaAbstract: Cancer is, by definition, the uncontrolled growth of autonomous cells that eventually destroy adjacent tissues and generate architectural disorder. However, this concept cannot be totally true. In three well documented studies, we have demonstrated that cancer tissues produce order zones that evolve over time and generate embryoid body structures in a space-time interval. The authors decided to revise the macroscopic and microscopic material in well-developed malignant tumors in which embryoid bodies were identified to determine the phenotype characterization that serves as a guideline for easy recognition. The factors responsible for this morphogenesis are physical, bioelectric, and magnetic susceptibilities produced by crystals that act as molecular designers for the topographic gradients that guide the surrounding silhouette and establish tissue head-tail positional identities. The structures are located in amniotic-like cavities and show characteristic somite-like embryologic segmentation. Immunophenotypic study has demonstrated exclusion factor positional identity in relation to enolase-immunopositive expression of embryoid body and human chorionic gonadotropin immunopositivity exclusion factor expression in the surrounding tissues. The significance of these observations is that they can also be predicted by experimental image data collected by the Large Hadron Collider (LHC accelerator at the European Organization for Nuclear Research, in which two-beam subatomic collision particles in the resulting debris show hyperorder domains similar to those identified by us in intercellular cancer collisions. Our findings suggest that we are dealing with true reverse biologic system information in an activated collective cancer stem cell

Collision induced fragmentation dynamics of small metallic clusters; Dynamique de fragmentation induite par collision de petits agregats metalliques

Energy Technology Data Exchange (ETDEWEB)

Picard, Y

1999-04-15

The goal of this work is the complete analysis of the fragmentation of alkali clusters (Na{sub n}{sup +} (n < 10), NaK{sup +} and K{sub 2}{sup +}) induced by collision with light atomic (He) or molecular (H{sub 2}) targets. The main point is to study how the energy is transmitted to the cluster during the collision and how this energy is shared among the various degrees of freedom of the system and leads to its fragmentation. Two types of interactions govern the collision induced dissociation processes: on one hand, the electronic mechanisms where the target perturbs the electronic cloud and brings the molecule into a dissociative state, and on the other hand, the impulsive mechanisms where the momentum transferred to the atomic cores leads to the rotational-vibrational dissociation of the molecule. The experimental procedure is based on the measurement of the velocity vectors of the outgoing fragments detected in coincidence. This allows to reconstruct the full kinematics of the fragmentation and to separate and characterize for the first time the two types of interactions. The two basic mechanisms of collision induced dissociation are then clearly resolved for the diatomic molecule Na{sub 2}{sup +}. For the heteronuclear molecular ion NaK{sup +}, it is shown that the dissociation process is due to a combination of electronic and impulsive mechanisms in some of the dissociation pathways. The extension to the study of metallic clusters Na{sub n}{sup +} (n < 10) fragmentation shows the role and the relative importance of the electronic and impulsive mechanisms and their evolution with the cluster size. The complete analysis of Na{sub 3}{sup +} multi-fragmentation is also presented. (author)

Lorre cluster: an outcome of recent asteroid collision

Science.gov (United States)

Novakovic, B.; Dell'Oro, A.; Cellino, A.; Knezevic, Z.

2012-09-01

Here we show an example of a young asteroid cluster located in a dynamically stable region, which was produced by partial disruption of a primitive body about 30 km in size. According to our estimation it is only 1.9±0.3 Myr old, thus its post-impact evolution is very limited. The parent body had a large orbital inclination, and was subject to collisions with typical impact speeds higher by a factor of 2 than in the most common situations encountered in the main belt. For the first time we have at disposal the observable outcome of a very recent event to study high-speed collisions involving primitive asteroids.

Initial state q q g correlations as a background for the chiral magnetic effect in collision of small systems

Science.gov (United States)

Kovner, Alex; Lublinsky, Michael; Skokov, Vladimir

2017-11-01

Motivated by understanding the background to chiral magnetic effect in proton-nucleus collisions from first principles, we compute the three particle correlation in the projectile wave function. We extract the correlations between two quarks and one gluon in the framework of the color glass condensate. This is related to the same-charge correlation of the conventional observable for the chiral magnetic effect. We show that there are two different contributions to this correlation function. One contribution is rapidity-independent and as such can be identified with the pedestal; while the other displays rather strong rapidity dependence. The pedestal contribution and the rapidity-dependent contribution at large rapidity separation between the two quarks result in the negative same charge correlations, while at small rapidity separation the second contribution changes sign. We argue that the computed initial state correlations might be partially responsible for the experimentally observed signal in proton-nucleus collisions.

Galaxy collisions

International Nuclear Information System (INIS)

Combes, F.

1987-01-01

Galaxies are not isolated systems of stars and gas, ''independent universes'' as believed by astronomers about ten years ago, but galaxies are formed and evolve by interaction with their environment, and in particular with their nearest neighbors. Gravitational interactions produce enormous tides in the disk of spiral galaxies, generate spiral arms and trigger bursts of star formation. Around elliptical galaxies, the collision with a small companion produces a series of waves, or shells. A galaxy interaction leads, in most cases, to the coalescence of the two coliders; therefore all galaxies are not formed just after the Big-Bang, when matter recombines: second generation galaxies are still forming now by galaxy mergers, essentially elliptical galaxies, but also compact dwarfs. Collisions between galaxies could also trigger activity in nuclei for radiogalaxies and quasars [fr

High energy hadron-hadron collisions. Annual progress report

International Nuclear Information System (INIS)

Chou, T.T.

1979-03-01

Work on high energy hadron-hadron collisions in the geometrical model, performed under the DOE Contract No. EY-76-S-09-0946, is summarized. Specific items studied include the behavior of elastic hadron scatterings at super high energies and the existence of many dips, the computation of meson radii in the geometrical model, and the hadronic matter current effects in inelastic two-body collisions

Flow of strange and charged particles in pPb and PbPb collisions at LHC energies

CERN Document Server

AUTHOR|(CDS)2083811

2016-01-01

Observation of a long-range near-side two-particle correlation (known as the``Ridge'') in high-multiplicity pPb and pp collisions opened up new opportunities of exploring novel QCD dynamics in small collision systems. Latest CMS results in pPb and PbPb collisions will be shown: (1) The multi-particle correlation in pPb collisions will be presented for the high multiplicity events, indicating the collective behavior in small collision systems. (2) Identified $p_T$ spectra of $\\pi^{+}/\\pi^{-}$, $K^{+}/K^{-}$, and $p/\\bar{p}$ in pPb collisions show a strong multiplicity dependence, which indicates radial flow at high multiplicity events. (3) The second-order anisotropy harmonics ($v_2$) of strange particle $K^{0}_{s}$ and $\\Lambda/\\bar{\\Lambda}$ are extracted from long-range correlations as a function of particle multiplicity and $p_T$. The mass ordering effect of $v_n$ at low $p_T$ as predicted by hydrodynamics also points to the strong collective nature of expanding medium in small collision systems. Finally, ...

A clinically feasible method for the detection of potential collision in proton therapy

Energy Technology Data Exchange (ETDEWEB)

Zou Wei; Lin Haibo; Plastaras, John P.; Wang Huanshu; Bui, Viet; Vapiwala, Neha; McDonough, James; Tochner, Zelig; Both, Stefan [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States) and Department of Mechanical Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2012-11-15

Purpose: Potential collision between the patient/couch and the gantry could delay the start of the treatment and reduce clinical efficiency. The ability to accurately detect possible collisions during the treatment planning phase is desired. Such collision detection should account for the specific proton gantry design, the treatment beam configuration, couch orientation, and the patient specific geometry. In this paper the authors developed an approach to detect possible patient-machine collisions using patient treatment plan data. Methods: The geometry of the machine and the patient was reconstructed relative to the isocenter of the proton treatment room. The surface contour of the gantry was first captured from the proton computer aided design and reconstructed to account for specific gantry rotation, snout position, collimator rotation, and range compensator dimensions based on the patient treatment plan data. The patient body and couch contours were captured from the patient's CT DICOM structure file. They were reconstructed relative to the isocenter taking into account treatment couch rotation. For potential collision that occurs at body portions where no CT images exist, scout images are used to construct the body contour. A software program was developed using a ray casting algorithm that was applied to detect collisions by determining if any of the patient and couch contour points fall into the spatial polygons formed by the proton gantry surfaces. Results: Twenty-four patient plans with or without potential collisions were retrospectively identified and analyzed using the collision detection software. In addition, five collision cases were artificially generated using an anthropomorphic phantom. The program successfully detected the collisions in all cases. The calculation time for each case was within 20 s. The software program was implemented in the authors' clinic to detect patient-gantry or gantry-couch collisions in the treatment planning

Origins of collectivity in small systems

Science.gov (United States)

Schenke, Björn

2017-11-01

We review recent developments in the theoretical description and understanding of multi-particle correlation measurements in collisions of small projectiles (p/d/3He) with heavy nuclei (Au, Pb) as well as proton+proton collisions. We focus on whether the physical processes responsible for the observed long range rapidity correlations and their azimuthal structure are the same in small systems as in heavy ion collisions. In the latter they are interpreted as generated by the initial spatial geometry being transformed into momentum correlations by strong final state interactions. However, explicit calculations show that also initial state momentum correlations are present and could contribute to observables in small systems. If strong final state interactions are present in small systems, recent developments show that results are sensitive to the shape of the proton and its fluctuations.

Small-scale soft-bodied robot with multimodal locomotion

Science.gov (United States)

Hu, Wenqi; Lum, Guo Zhan; Mastrangeli, Massimo; Sitti, Metin

2018-02-01

Untethered small-scale (from several millimetres down to a few micrometres in all dimensions) robots that can non-invasively access confined, enclosed spaces may enable applications in microfactories such as the construction of tissue scaffolds by robotic assembly, in bioengineering such as single-cell manipulation and biosensing, and in healthcare such as targeted drug delivery and minimally invasive surgery. Existing small-scale robots, however, have very limited mobility because they are unable to negotiate obstacles and changes in texture or material in unstructured environments. Of these small-scale robots, soft robots have greater potential to realize high mobility via multimodal locomotion, because such machines have higher degrees of freedom than their rigid counterparts. Here we demonstrate magneto-elastic soft millimetre-scale robots that can swim inside and on the surface of liquids, climb liquid menisci, roll and walk on solid surfaces, jump over obstacles, and crawl within narrow tunnels. These robots can transit reversibly between different liquid and solid terrains, as well as switch between locomotive modes. They can additionally execute pick-and-place and cargo-release tasks. We also present theoretical models to explain how the robots move. Like the large-scale robots that can be used to study locomotion, these soft small-scale robots could be used to study soft-bodied locomotion produced by small organisms.

Studies of fluctuation processes in nuclear collisions

International Nuclear Information System (INIS)

Ayik, S.

1991-02-01

This report summarizes the progress on grant No. DE-FG05-89ER40530 during the period April 15, 1990 to February 15, 1991. Our studies of heavy-ion collisions in the framework of ''a stochastic one-body transport model'' has progress in several directions. We developed a method for obtaining approximate numerical solutions of the transport-equation in semi-classical limit, i.e., Boltzmann-Langevin equation, and tested the method in realistic cases of heavy-ion collisions at energies below 100 MeV per nucleon. Some results of the numerical simulations for a head-on collision of 12 C + 12 C system is included in this report. Work has also continued on studying the stochastic one-body transport model in a quantal representation, which provides a microscopic basis for a consistent description of dissipation and fluctuation properties of large amplitude collective nuclear motion. The previous derivation of the stochastic one-body transport model was presented within the density matrix formalisam. We generalized this treatment and proposed an alternative derivation of the model by employing the Green's function approach within the real-time path formalism of Keldish. One manuscript has been submitted to Nucl. Phys. A for publication. Two other manuscripts are in preparation for publication. Several seminars and contributed talks were presented at various meeting

Toolbox for Research and Exploration (TREX): Investigations of Fine-Grained Materials on Small Bodies

Science.gov (United States)

Domingue, D. L.; Allain, J.-P.; Banks, M.; Christoffersen, R.; Cintala, M.; Clark, R.; Cloutis, E.; Graps, A.; Hendrix, A. R.; Hsieh, H.;

Improved elastic collision modeling in DEGAS 2 for low-temperature plasmas

International Nuclear Information System (INIS)

Kanzleiter, Randall J.; Stotler, Daren P.; Karney, Charles F. F.; Steiner, Don

2000-01-01

Recent emphasis on low-temperature divertor operations has focused attention on proper treatment of neutral-elastic collisions in low-temperature environments. For like species collisions, as in D + +D, quantum mechanical indistinguishability precludes differentiation of small-angle elastic scattering from resonant charge exchange for collision energies + +D 2 are included for the first time. An integration technique is utilized that reduces the total collision cross section while keeping the other transport cross sections invariant. The inclusion of ion-molecular elastic collisions results in significant increases in energy exchange between background ions and neutral test species

Evaluation of Severity Score in Patients with Lower Limb and Pelvic Fractures Injured in Motor Vehicle Front-Impact Collisions.

Science.gov (United States)

Gokalp, Mehmet Ata; Hekimoglu, Yavuz; Gozen, Abdurrahim; Guner, Savas; Asirdizer, Mahmut

2016-12-01

BACKGROUND Lower limb and pelvic injuries and fractures occur at a very high incidence in motor vehicle accidents. In this study, the characteristics (e.g., body side, bone location, and fracture severity) of lower limb and pelvic fractures that occurred during front-impact collisions were correlated with the injured patients' sex, age, and position in the vehicle. MATERIAL AND METHODS We retrospectively evaluated 191 patients (136 males, 55 females) who were injured in motor vehicle accidents, specifically in frontal collisions. RESULTS This study revealed that most of lower limb and pelvic fractures occurred in males (71.2%; p=.000), 19-36 years old (55.5%; p=.000), small vehicles (86.4%; p=.000), and rear seat passengers (49.2%; p=.000). Fractures most commonly occurred in the left side of the body (46.6%; p=.000) and upper legs (37.7%; p=.000). Severity scores were higher (2.76) in males than females (2.07). No statistically significant was found in severity scores of patients and other personal characteristics and fracture features of patients with lower limb and pelvic fractures who were injured in a vehicle during front-impact collisions (p>0.05). CONCLUSIONS The results of this study will be useful for the automobile industry, forensics and criminal scientists, and for trauma research studies.

THE SMALL BODY GEOPHYSICAL ANALYSIS TOOL

Science.gov (United States)

Bercovici, Benjamin; McMahon, Jay

2017-10-01

The Small Body Geophysical Analysis Tool (SBGAT) that we are developing aims at providing scientists and mission designers with a comprehensive, easy to use, open-source analysis tool. SBGAT is meant for seamless generation of valuable simulated data originating from small bodies shape models, combined with advanced shape-modification properties.The current status of SBGAT is as follows:The modular software architecture that was specified in the original SBGAT proposal was implemented in the form of two distinct packages: a dynamic library SBGAT Core containing the data structure and algorithm backbone of SBGAT, and SBGAT Gui which wraps the former inside a VTK, Qt user interface to facilitate user/data interaction. This modular development facilitates maintenance and addi- tion of new features. Note that SBGAT Core can be utilized independently from SBGAT Gui.SBGAT is presently being hosted on a GitHub repository owned by SBGAT’s main developer. This repository is public and can be accessed at https://github.com/bbercovici/SBGAT. Along with the commented code, one can find the code documentation at https://bbercovici.github.io/sbgat-doc/index.html. This code documentation is constently updated in order to reflect new functionalities.SBGAT’s user’s manual is available at https://github.com/bbercovici/SBGAT/wiki. This document contains a comprehensive tutorial indicating how to retrieve, compile and run SBGAT from scratch.Some of the upcoming development goals are listed hereafter. First, SBGAT's dynamics module will be extented: the PGM algorithm is the only type of analysis method currently implemented. Future work will therefore consists in broadening SBGAT’s capabilities with the Spherical Harmonics Expansion of the gravity field and the calculation of YORP coefficients. Second, synthetic measurements will soon be available within SBGAT. The software should be able to generate synthetic observations of different type (radar, lightcurve, point clouds

Heavy ion collisions at intermediate energy

International Nuclear Information System (INIS)

Bertsch, G.; Amsden, A.A.

1978-01-01

Two types of measurement are proposed for the analysis of heavy ion collisions in the range of energy of 20--200 MeV/A. First, measurement of the longitudinal component of the kinetic energy of the collision products characterizes the impact parameter of the collision. The distribution in this quantity allows the dissipation in the theoretical models to be determined. A second kind of measurement is that of the coefficients of a spherical harmonic expansion of the angular distribution of the products. Besides giving independent information on the impact parameter and reaction dynamics, measurement of these coefficients offers the possibility of measuring the stiffness of the equation of state of nuclear matter. These ideas are explored in the context of a hydrodynamic model for the collision. In the purely hydrodynamic model there is a large measurable asymmetry in the angular distribution, but the dependence on the equation of state is small

Chaotic Zones around Rotating Small Bodies

Energy Technology Data Exchange (ETDEWEB)

Lages, José; Shevchenko, Ivan I. [Institut UTINAM, Observatoire des Sciences de l’Univers THETA, CNRS, Université de Franche-Comté, Besançon F-25030 (France); Shepelyansky, Dima L., E-mail: jose.lages@utinam.cnrs.fr [Laboratoire de Physique Théorique du CNRS, IRSAMC, Université de Toulouse, UPS, Toulouse F-31062 (France)

2017-06-01

Small bodies of the solar system, like asteroids, trans-Neptunian objects, cometary nuclei, and planetary satellites, with diameters smaller than 1000 km usually have irregular shapes, often resembling dumb-bells or contact binaries. The spinning of such a gravitating dumb-bell creates around it a zone of chaotic orbits. We determine its extent analytically and numerically. We find that the chaotic zone swells significantly if the rotation rate is decreased; in particular, the zone swells more than twice if the rotation rate is decreased 10 times with respect to the “centrifugal breakup” threshold. We illustrate the properties of the chaotic orbital zones in examples of the global orbital dynamics about asteroid 243 Ida (which has a moon, Dactyl, orbiting near the edge of the chaotic zone) and asteroid 25143 Itokawa.

Hydrodynamic evolution and jet energy loss in Cu + Cu collisions

International Nuclear Information System (INIS)

Schenke, Bjoern; Jeon, Sangyong; Gale, Charles

2011-01-01

We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.

Collision Risk and Damage after Collision

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Hansen, Peter Friis; Nielsen, Lars Peter

1996-01-01

The paper presents a new and complete procedure for calculation of ship-ship collision rates on specific routes and the hull damage caused by such collisions.The procedure is applied to analysis of collision risks for Ro-Ro pasenger vessels. Given a collision the spatial probability distribution ...

Study of post-collision effect on autoionisation electron spectra in He+-He collision

International Nuclear Information System (INIS)

Ioannis, K.

1981-11-01

Energy spectra of electrons ejected by autoionisation of the helium atom have been measured at low collision energy (3-20 keV) in the He + -He collision system. Perturbations of the line shapes due to the Coulomb field of the spectator ion are studied. Our results are compared with the semi classical model of MORGENSTERN et al. Only for small (or great) emission angles relative phases as well as moduli of transition amplitudes towards the Msub(L)=0 sublevel of the 2p 2 1 D and 2s2p 1 P states are deduced. Near the 2s 2 1 S line, strong discrepancies with the model are observed (at thetasub(Lab)=11 0 ) which are attributed to a contribution of autoionisation in the quasimolecule. Angular distributions have also been measured which seem to be not perturbed by the Coulomb field. An unexplained oscillatory behaviour of the singly differential cross section, when plotted against the collision energy has also been observed [fr

The role of electrostatic charging of small and intermediate sized bodies in the solar system

International Nuclear Information System (INIS)

Mendis, D.A.

1981-01-01

The role of electrostatic charging of small and intermediate sized bodies in the solar system is reviewed. These bodies include planetary, interplanetary and cometary dust as well as cometary nuclei (at large heliocentric distances), asteroids and the larger bodies in the Saturnian ring system. While this charging has both physical and dynamical consequences for the small dust grains, it has only physical consequences for the larger bodies. The main physical consequences for the small grains are electrostatic erosion (''chipping'') and disruption, whereas for the larger bodies they include electrostatic levitation and blow-off of fine loose dust from their surfaces. A large variety of solar system phenomena, recently observed by the Pioneer and Voyager deep space probes as well as the HEOS-2 earth satellite, are explained in terms of these processes. Certain peculiar features observed in the dust tails of comets as well as the spatial orientation of the zodiacal dust cloud may also be explained along these lines. The possible electrostatic erosion of the dust mantles of new comets as well as the electrostatic 'polishing' of the smaller asteroids are also discussed. (Auth.)

Crossing geometry for Main Ring on Doubler collisions

International Nuclear Information System (INIS)

Diebold, R.

1977-01-01

There are two basic methods for bringing about Main Ring on Doubler collisions: the transposed, and kissing geometries. Examples of both are discussed assuming maximum momenta of 250 on 1000 GeV/c. The magnets required to bring the beams into small-angle collision are substantial in both cases. Detailed engineering work will be required to distinguish a substantial cost advantage of one geometry over the other

A quasi-classical study of energy transfer in collisions of hyperthermal H atoms with SO2 molecules.

Science.gov (United States)

da Silva, Ramon S; Garrido, Juan D; Ballester, Maikel Y

2017-08-28

A deep understanding of energy transfer processes in molecular collisions is at central attention in physical chemistry. Particularly vibrational excitation of small molecules colliding with hot light atoms, via a metastable complex formation, has shown to be an efficient manner of enhancing reactivity. A quasi-classical trajectory study of translation-to-vibration energy transfer (T-V ET) in collisions of hyperthermal H( 2 S) atoms with SO 2 (X̃ 1 A ' ) molecules is presented here. For such a study, a double many-body expansion potential energy surface previously reported for HSO 2 ( 2 A) is used. This work was motivated by recent experiments by Ma et al. studying collisions of H + SO 2 at the translational energy of 59 kcal/mol [J. Ma et al., Phys. Rev. A 93, 040702 (2016)]. Calculations reproduce the experimental evidence that during majority of inelastic non-reactive collision processes, there is a metastable intermediate formation (HOSO or HSO 2 ). Nevertheless, the analysis of the trajectories shows that there are two distinct mechanisms in the T-V ET process: direct and indirect. Direct T-V processes are responsible for the high population of SO 2 with relatively low vibrational excitation energy, while indirect ones dominate the conversion from translational energy to high values of the vibrational counterpart.

Big cat, small cat: reconstructing body size evolution in living and extinct Felidae.

Science.gov (United States)

Cuff, A R; Randau, M; Head, J; Hutchinson, J R; Pierce, S E; Goswami, A

2015-08-01

The evolution of body mass is a fundamental topic in evolutionary biology, because it is closely linked to manifold life history and ecological traits and is readily estimable for many extinct taxa. In this study, we examine patterns of body mass evolution in Felidae (Placentalia, Carnivora) to assess the effects of phylogeny, mode of evolution, and the relationship between body mass and prey choice in this charismatic mammalian clade. Our data set includes 39 extant and 26 extinct taxa, with published body mass data supplemented by estimates based on condylobasal length. These data were run through 'SURFACE' and 'bayou' to test for patterns of body mass evolution and convergence between taxa. Body masses of felids are significantly different among prey choice groupings (small, mixed and large). We find that body mass evolution in cats is strongly influenced by phylogeny, but different patterns emerged depending on inclusion of extinct taxa and assumptions about branch lengths. A single Ornstein-Uhlenbeck optimum best explains the distribution of body masses when first-occurrence data were used for the fossil taxa. However, when mean occurrence dates or last known occurrence dates were used, two selective optima for felid body mass were recovered in most analyses: a small optimum around 5 kg and a large one around 100 kg. Across living and extinct cats, we infer repeated evolutionary convergences towards both of these optima, but, likely due to biased extinction of large taxa, our results shift to supporting a Brownian motion model when only extant taxa are included in analyses. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Theory of and effects from elastoplasticity in nucleus-nucleus collisions

International Nuclear Information System (INIS)

Noerenberg, W.; Technische Hochschule Darmstadt

1985-02-01

Elastoplasticity of finite Fermi systems results from a coherent coupling between collective and intrinsic degrees of freedom and subsequent equilibration essentially due to two-body collisions. Within a non-markovian transport-theoretical approach referred to as dissipative diabatic dynamics (DDD), elastoplastical forms the link between giant vibrations and overdamped motion of nuclear. Obersvable effects resulting from this non-markovian behaviour in nucleus-nucleus collisions are discussed. (orig.)

Transfer, loss and physical processing of water in hit-and-run collisions of planetary embryos

Science.gov (United States)

Burger, C.; Maindl, T. I.; Schäfer, C. M.

2018-01-01

Collisions between large, similar-sized bodies are believed to shape the final characteristics and composition of terrestrial planets. Their inventories of volatiles such as water are either delivered or at least significantly modified by such events. Besides the transition from accretion to erosion with increasing impact velocity, similar-sized collisions can also result in hit-and-run outcomes for sufficiently oblique impact angles and large enough projectile-to-target mass ratios. We study volatile transfer and loss focusing on hit-and-run encounters by means of smooth particle hydrodynamics simulations, including all main parameters: impact velocity, impact angle, mass ratio and also the total colliding mass. We find a broad range of overall water losses, up to 75% in the most energetic hit-and-run events, and confirm the much more severe consequences for the smaller body also for stripping of volatile layers. Transfer of water between projectile and target inventories is found to be mostly rather inefficient, and final water contents are dominated by pre-collision inventories reduced by impact losses, for similar pre-collision water mass fractions. Comparison with our numerical results shows that current collision outcome models are not accurate enough to reliably predict these composition changes in hit-and-run events. To also account for non-mechanical losses, we estimate the amount of collisionally vaporized water over a broad range of masses and find that these contributions are particularly important in collisions of ˜ Mars-sized bodies, with sufficiently high impact energies, but still relatively low gravity. Our results clearly indicate that the cumulative effect of several (hit-and-run) collisions can efficiently strip protoplanets of their volatile layers, especially the smaller body, as it might be common, e.g., for Earth-mass planets in systems with Super-Earths. An accurate model for stripping of volatiles that can be included in future planet

Experimental overview on flow observables in heavy ion collisions

Energy Technology Data Exchange (ETDEWEB)

Mohapatra, Soumya, E-mail: soumya@cern.ch

2016-12-15

This paper summarizes the experimental results on flow phenomena that were presented at Quark matter 2015, with a focus on new flow observables and correlations in small systems. The results presented include event-shape selected p{sub T} spectra and v{sub n} measurements, correlations between flow harmonics of different orders, study of factorization breakdown in two-particle correlations, and principal component analysis of two-particle correlations. Recent developments in investigation of collective effects in small collisions systems, namely, p+A, d+A and {sup 3}He + A as well as in pp collisions are also presented.

Scattering of acoustic and electromagnetic waves by small impedance bodies of arbitrary shapes applications to creating new engineered materials

CERN Document Server

Ramm, Alexander G

2013-01-01

The behavior of acoustic or electromagnetic waves reflecting off, and scattering from, intercepted bodies of any size and kind can make determinations about the materials of those bodies and help in better understanding how to manipulate such materials for desired characteristics. This book offers analytical formulas which allow you to calculate acoustic and electromagnetic waves, scattered by one and many small bodies of an arbitrary shape under various boundary conditions. Equations for the effective (self-consistent) field in media consisting of many small bodies are derived. These results and formulas are new and not available in the works of other authors. In particular, the theory developed in this book is different from the classical work of Rayleigh on scattering by small bodies: not only analytical formulas are derived for the waves scattered by small bodies of an arbitrary shape, but the amplitude of the scattered waves is much larger, of the order O(a 2-k), than in Rayleigh scattering, where the or...

Quantification of surface energy fluxes from a small water body using scintillometry and eddy covariance

DEFF Research Database (Denmark)

McGloin, Ryan; McGowan, Hamish; McJannet, David

2014-01-01

Accurate quantification of evaporation from small water storages is essential for water management and planning, particularly in water-scarce regions. In order to ascertain suitable methods for direct measurement of evaporation from small water bodies, this study presents a comparison of eddy......% greater than eddy covariance measurements. We suggest possible reasons for this difference and provide recommendations for further research for improving measurements of surface energy fluxes over small water bodies using eddy covariance and scintillometry. Key Points Source areas for Eddy covariance...... and scintillometry were on the water surface Reasonable agreement was shown between the sensible heat flux measurements Scintillometer estimates of latent heat flux were greater than eddy covariance...

Posture does not matter! Paw usage and grasping paw preference in a small-bodied rooting quadrupedal mammal.

Science.gov (United States)

Joly, Marine; Scheumann, Marina; Zimmermann, Elke

2012-01-01

Recent results in birds, marsupials, rodents and nonhuman primates suggest that phylogeny and ecological factors such as body size, diet and postural habit of a species influence limb usage and the direction and strength of limb laterality. To examine to which extent these findings can be generalised to small-bodied rooting quadrupedal mammals, we studied trees shrews (Tupaia belangeri). We established a behavioural test battery for examining paw usage comparable to small-bodied primates and tested 36 Tupaia belangeri. We studied paw usage in a natural foraging situation (simple food grasping task) and measured the influence of varying postural demands (triped, biped, cling, sit) on paw preferences by applying a forced-food grasping task similar to other small-bodied primates. Our findings suggest that rooting tree shrews prefer mouth over paw usage to catch food in a natural foraging situation. Moreover, we demonstrated that despite differences in postural demand, tree shrews show a strong and consistent individual paw preference for grasping across different tasks, but no paw preference at a population level. Tree shrews showed less paw usage than small-bodied quadrupedal and arboreal primates, but the same paw preference. Our results confirm that individual paw preferences remain constant irrespective of postural demand in some small-bodied quadrupedal non primate and primate mammals which do not require fine motoric control for manipulating food items. Our findings suggest that the lack of paw/hand preference for grasping food at a population level is a universal pattern among those species and that the influence of postural demand on manual lateralisation in quadrupeds may have evolved in large-bodied species specialised in fine manipulations of food items.

Differential cross section study of fragment production, at small angle, in relativistic heavy ion collisions. Application at a calculation of heavy ion beam transport in the matter

International Nuclear Information System (INIS)

Morel, P.

1992-02-01

Relativistic heavy ion collisions present the opportunity of creating in laboratory small volumes of hot, dense nuclear matter. On the experimental point of view, the collision events are characterized by a great number of fragments, especially in the direction of the projectile. The first part is devoted to a survey of relativistic heavy ion physics. Then, we present two experimental set-ups which permit, in particular, the analyse of light fragment production at small angles. We present experimental results concerning light projectiles on Ca, Nb, Pb targets, with energies from 200 A.MeV up to 600 A.MeV. Different aspects of the collision are put in evidence. Momentum and charge differential cross section are extrapolated to other projectile/target systems; that is used in a transport calculation of Ne ions in a target of biological interest (water), with a collimator. We show that nuclear fragmentation produces a dispersion in the spatial and energy distributions, and that one light fragments have a range greater than the projectile range. That last point causes a distortion of the Bragg curve, and that distortion must be taken into account for the application of heavy ions to radiotherapy problems. 95 figs., 8 tabs

Collisions with Springs: A Useful Context for the Study of Analytical Dynamics

Science.gov (United States)

Twomey, Patrick; O'Sullivan, Colm; O'Riordan, John; Fahy, Stephen

2012-01-01

A recent paper in this journal describes an experimental demonstration of the conservation of total momentum before, during, and after an elastic collision between two bodies. The experiment also appears to show that total kinetic energy is conserved in the process, including "during" the collision. There is a danger that this may give rise to…

Nuclear collision theory with many-body correlations, 1

International Nuclear Information System (INIS)

Kurihara, Yukio.

1984-11-01

A generalized many-body correlation operator is introduced, following the Feshbach's formalism. Especially, the many-body correlation induced by the strong repulsion and attraction of the realistic NN interaction is concerned and the Feshbach's formalism is reformulated to describe such a many-body correlation well. And a method to estimate the many-body correlation operator is given from the multiple-scattering picture. The present formalism is compared with the resonating-group method. (author)

Effect of ice surface size on collision rates and head impacts at the World Junior Hockey Championships, 2002 to 2004.

Science.gov (United States)

Wennberg, Richard

2005-03-01

To determine if collision rates and head impacts in elite junior hockey differed between games played on the small North American ice surface (85 ft wide), an intermediate-size Finnish ice surface (94 ft wide), and the large standard international ice surface (100 ft wide). Videotape analysis of all games involving Team Canada from the 2002 (large ice, Czech Republic), 2003 (small ice, Canada), and 2004 (intermediate ice, Finland) World Junior Championships. All collisions were counted and separated into various categories (volitional player/player bodychecks, into boards or open ice, plus accidental/incidental player/boards, player/ice, head/stick, head/puck). Further subdivisions included collisions involving the head directly or indirectly and notably severe head impacts. Small, intermediate, and large ice surface mean collisions/game, respectively, were 295, 258, 222, total collisions; 251, 220, 181, volitional bodychecks; 126, 115, 88, into boards; 125, 106, 93, open ice; 71, 52, 44, total head; 44, 36, 30, indirect head; 26, 16, 13, direct head; and 1.3, 0.5, 0.3, severe head (P < 0.05 for small-intermediate ice and intermediate-large ice differences in total collisions; P < 0.005 for small-large ice difference; P < 0.05 for small-intermediate ice differences in head impacts; P < 0.01 for small-large ice differences in total and severe head impacts). There is a significant inverse correlation between ice size and collision rates in elite hockey, including direct, indirect, and severe head impacts. These findings suggest that uniform usage of the larger international rinks could reduce the risk of injury, and specifically, concussions in elite hockey by decreasing the occurrence of collisions and head impacts.

Posture does not matter! Paw usage and grasping paw preference in a small-bodied rooting quadrupedal mammal.

Directory of Open Access Journals (Sweden)

Marine Joly

Full Text Available BACKGROUND: Recent results in birds, marsupials, rodents and nonhuman primates suggest that phylogeny and ecological factors such as body size, diet and postural habit of a species influence limb usage and the direction and strength of limb laterality. To examine to which extent these findings can be generalised to small-bodied rooting quadrupedal mammals, we studied trees shrews (Tupaia belangeri. METHODOLOGY/PRINCIPAL FINDINGS: We established a behavioural test battery for examining paw usage comparable to small-bodied primates and tested 36 Tupaia belangeri. We studied paw usage in a natural foraging situation (simple food grasping task and measured the influence of varying postural demands (triped, biped, cling, sit on paw preferences by applying a forced-food grasping task similar to other small-bodied primates. Our findings suggest that rooting tree shrews prefer mouth over paw usage to catch food in a natural foraging situation. Moreover, we demonstrated that despite differences in postural demand, tree shrews show a strong and consistent individual paw preference for grasping across different tasks, but no paw preference at a population level. CONCLUSIONS/SIGNIFICANCE: Tree shrews showed less paw usage than small-bodied quadrupedal and arboreal primates, but the same paw preference. Our results confirm that individual paw preferences remain constant irrespective of postural demand in some small-bodied quadrupedal non primate and primate mammals which do not require fine motoric control for manipulating food items. Our findings suggest that the lack of paw/hand preference for grasping food at a population level is a universal pattern among those species and that the influence of postural demand on manual lateralisation in quadrupeds may have evolved in large-bodied species specialised in fine manipulations of food items.

Macroscopic and microscopic description of HE-HI collisions; classical equations of motion calculations

International Nuclear Information System (INIS)

Bodmer, A.R.

1978-01-01

The study of high energy heavy ion reactions includes the three principle a priori approaches used for central collisions, namely, hydrodynamics, cascade--Boltzman equation, and the classical equations of motion. While no clearly justified central or near central collisions are found, the classical equations of motion are used to illustrate some general features of these reactions. It is expected that the hot nuclear matter produced in such collisions is a dense, viscous, and thermally conductive fluid with important nonequilibrium and nonclassical features, rapidity, distribution, noncentral collisions, potential dependent effects for a given two-body scattering, and c.m. cross sections for a central collision with given parameters are among the properties considered. 12 references

First-principle proof of the modified collision boundary conditions for the hard-sphere system

International Nuclear Information System (INIS)

Tessarotto, Massimo; Cremaschini, Claudio

2014-01-01

A fundamental issue lying at the foundation of classical statistical mechanics is the determination of the collision boundary conditions that characterize the dynamical evolution of multi-particle probability density functions (PDF) and are applicable to systems of hard-spheres undergoing multiple elastic collisions. In this paper it is proved that, when the deterministic N-body PDF is included in the class of admissible solutions of the Liouville equation, the customary form of collision boundary conditions adopted in previous literature becomes physically inconsistent and must actually be replaced by suitably modified collision boundary conditions.

Three-body recombination of cold fermionic atoms

International Nuclear Information System (INIS)

Suno, H; Esry, B D; Greene, Chris H

2003-01-01

Recombination of identical, spin-polarized fermions in cold three-body collisions is investigated. We parametrize the mechanisms for recombination in terms of the 'scattering volume' V p and another length scale r 0 . Model two-body interactions were used within the framework of the adiabatic hyperspherical representation. We examine the recombination rate K 3 as a function of the collision energy E for various values of V p . Not only do we consider the dominant J Π = 1 + case, but also the next-leading order contributions from J Π = 1 - and 3 - . We discuss the behaviour near a two-body resonance and the expected universality of fermionic recombination. Comparisons with boson recombination are considered in detail

Two- and multi-particle azimuthal correlations in small collision systems with the ATLAS detector

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00256459; The ATLAS collaboration

2017-01-01

The recent ATLAS results on two- and multi-particle azimuthal correlations of charged particles are presented for $\\sqrt{s}$=~5.02 TeV and 13 TeV $pp$, $\\sqrt{s_\\mathrm{NN}}$= 5.02 TeV $p$+Pb and $\\sqrt{s_\\mathrm{NN}}$= 2.76 TeV low-multiplicity Pb+Pb collisions. To remove the "non-flow" contribution from the correlations, that arises predominantly from hard-scattering processes, a template fitting procedure is used in the two-particle correlations (2PC) measurements, while for multi-particle correlations the cumulant method is applied. The correlations are expressed in the form of Fourier harmonics $\\mathrm{v}_n (n=2,3,4)$ measuring the global azimuthal anisotropy. The measurements presented hereafter confirm the evidence for collective phenomena in $p$+Pb and low-multiplicity Pb+Pb collisions. For $pp$ collisions the results on four-particle cumulants do not demonstrate a similar collective behaviour.

Estimating Small-Body Gravity Field from Shape Model and Navigation Data

Science.gov (United States)

Park, Ryan S.; Werner, Robert A.; Bhaskaran, Shyam

2008-01-01

This paper presents a method to model the external gravity field and to estimate the internal density variation of a small-body. We first discuss the modeling problem, where we assume the polyhedral shape and internal density distribution are given, and model the body interior using finite elements definitions, such as cubes and spheres. The gravitational attractions computed from these approaches are compared with the true uniform-density polyhedral attraction and the level of accuracies are presented. We then discuss the inverse problem where we assume the body shape, radiometric measurements, and a priori density constraints are given, and estimate the internal density variation by estimating the density of each finite element. The result shows that the accuracy of the estimated density variation can be significantly improved depending on the orbit altitude, finite-element resolution, and measurement accuracy.

Ultra-peripheral collisions of relativistic heavy ions

International Nuclear Information System (INIS)

Klein, S.; STAR Collaboration

2001-01-01

We report the first observation of exclusive ρ production in ultra-peripheral collisions at RHIC. The ρ are produced electromagnetically at large impact parameters where no hadronic interactions occur. The produced ρ have a small perpendicular momentum, consistent with production that is coherent on both the photon emitting and scattering nuclei. We observe both exclusive ρ production, and ρ production accompanied by electromagnetic dissociation of both nuclei. We discuss models of vector meson production and the correlation with nuclear breakup. We also observe e + e - pair production in these ultra-peripheral collisions

Modeling collisions in circumstellar debris disks

Science.gov (United States)

Nesvold, Erika

2015-10-01

resonances near the chaotic zone. I investigate the effects of the initial eccentricity distribution of the disk particles and find a negligible effect on the gap size at Jovian planet masses, since collisions tend to erase memory of the initial particle eccentricity distributions. I also find that the presence of Trojan analogs is a potentially powerful diagnostic of planets in the mass range ˜1--10MJup. I apply my model to place new upper limits on planets around Fomalhaut, HR 4796 A, HD 202628, HD 181327, and beta Pictoris. Finally, to show how SMACK can be used to analyze a single debris disk in detail, I present a new model of the beta Pictoris disk and planet system that, for the first time, combines simulations of the colliding planetesimals and the dynamics of the dust grains, allowing me to model features and asymmetries in both submillimeter and scattered light images of the disk. I combine a 100,000 superparticle SMACK simulation with N-body integrations of the dust produced by the simulated collisions. I find that secular perturbations of the planet's measured inclination and eccentricity can explain the observed warp and planetesimal ring, while collisions between planetesimals shape the disk by eroding close-in material. The complex 3D structure of the disk due to the perturbations from the planet creates an azimuthally asymmetric spatial distribution of collisions, which could contribute to the observed azimuthal clump of CO gas seen with ALMA. My simulations of the small dust grains produced by collisions demonstrate that the "birth ring" approximation for beta Pictoris fails to account for the ˜54% of dust mass produced outside of the planetesimal ring. I also reproduce the gross morphology of high-resolution scattered light images of the disk, including the two-disk "x"-pattern seen in scattered light, which has not been replicated by previous dust dynamics models.

QCD Jets and particle correlations in heavy-ion collisions

CERN Document Server

Nguyen, Matthew

2017-01-01

Measurements of jets and particle correlations in nucleus-nucleus collisions are intended to probe QCD interactions in the high temperature phase, where matter is understood to behave as a quark-gluon plasma. Two probes are reviewed: jets which are used to study the energy loss of hard-scattered partons in this medium and particle correlations which are used to understand collective effects of the bulk matter. Whereas collisions of lighter systems, namely proton-ion and proton-proton, initially served primarily as control experiments, certain (but not all) effects first observed in nucleus-nucleus collisions have proven to be pervasive in these systems. Comparative measurements in these three systems have broadened our understanding of many-body QCD phenomena, and raised new questions. This talk reviewed these recent developments.

Human and Robotic Mission to Small Bodies: Mapping, Planning and Exploration

Science.gov (United States)

Neffian, Ara V.; Bellerose, Julie; Beyer, Ross A.; Archinal, Brent; Edwards, Laurence; Lee, Pascal; Colaprete, Anthony; Fong, Terry

2013-01-01

This study investigates the requirements, performs a gap analysis and makes a set of recommendations for mapping products and exploration tools required to support operations and scientific discovery for near- term and future NASA missions to small bodies. The mapping products and their requirements are based on the analysis of current mission scenarios (rendezvous, docking, and sample return) and recommendations made by the NEA Users Team (NUT) in the framework of human exploration. The mapping products that sat- isfy operational, scienti c, and public outreach goals include topography, images, albedo, gravity, mass, density, subsurface radar, mineralogical and thermal maps. The gap analysis points to a need for incremental generation of mapping products from low (flyby) to high-resolution data needed for anchoring and docking, real-time spatial data processing for hazard avoidance and astronaut or robot localization in low gravity, high dynamic environments, and motivates a standard for coordinate reference systems capable of describing irregular body shapes. Another aspect investigated in this study is the set of requirements and the gap analysis for exploration tools that support visualization and simulation of operational conditions including soil interactions, environment dynamics, and communications coverage. Building robust, usable data sets and visualisation/simulation tools is the best way for mission designers and simulators to make correct decisions for future missions. In the near term, it is the most useful way to begin building capabilities for small body exploration without needing to commit to specific mission architectures.

Human-robot collision detection under modeling uncertainty using frequency boundary of manipulator dynamics

Energy Technology Data Exchange (ETDEWEB)

Jung, Byung Jin; Koo, Ja Choon; Choi, Hyouk Ryeol; Moon, Hyung Pil [Sungkyunkwan University, Suwon (Korea, Republic of)

2014-11-15

This paper presents the development and experimental evaluation of a collision detection method for robotic manipulators sharing a workspace with humans. Fast and robust collision detection is important for guaranteeing safety and preventing false alarms. The main cause of a false alarm is modeling error. We use the characteristic of the maximum frequency boundary of the manipulator's dynamic model. The tendency of the frequency boundary's location in the frequency domain is applied to the collision detection algorithm using a band pass filter (band designed disturbance observer, BdDOB) with changing frequency windows. Thanks to the band pass filter, which considers the frequency boundary of the dynamic model, our collision detection algorithm can extract the collision caused by the disturbance from the mixed estimation signal. As a result, the collision was successfully detected under the usage conditions of faulty sensors and uncertain model data. The experimental result of a collision between a 7-DOF serial manipulator and a human body is reported.

Future directions in electron--ion collision physics

International Nuclear Information System (INIS)

Reed, K.J.; Griffin, D.C.

1992-01-01

This report discusses the following topics: Summary of session on synergistic co-ordination of theory and experiment; synergism between experiment and theory in atomic physics; comparison of theory and experiment for electron-ion excitation and ionization; summary of session on new theoretical and computational methods; new theoretical and computational methods-r-matrix calculations; the coulomb three-body problem: a progress report; summary of session on needs and applications for electron-ion collisional data; electron-ion collisions in the plasma edge; needs and applications of theoretical data for electron impact excitation; summary of session on relativistic effects, indirect effects, resonance, etc; direct and resonant processes in electron-ion collisions; relativistic calculations of electron impact ionization and dielectronic recombination cross section for highly charged ions; electron-ion recombination in the close-coupling approximation; modified resonance amplitudes with strongly correlated channels; a density-matrix approach to the broadening of spectral lines by autoionization, radiative transitions and electron-ion collisions; towards a time-dependent description of electron-atom/ion collisions two electron systems; and comments on inclusion of the generalized bright interaction in electron impact excitation of highly charged ions

Complete single ionization momentum spectra for strong perturbation collisions

International Nuclear Information System (INIS)

Olson, R.E.; Wood, C.J.

1997-09-01

The combination of recoil ion and ionized electron momentum spectroscopy provides an unparalleled method to investigate the details of ion-atom collision dynamics in kinematically complete experiments. To predict singleionization scattering behavior at the level now realized by experiment, the classical trajectory three-body Monte Carlo method has been used to obtain complete momenta information for the ionized electron, recoil ion, and projectile in the collision plane defined by the incident projectile and outgoing recoil ion. Strongly coupled systems were considered where the charge state of the projectile divided by the speed of the collision q/v is greater than unity. Illustrated are 3.6 MeV/u Se 28+ and 9.5 MeV/u Ni 26+ collisions on He where experimental data are available. The theoretical results are in good agreement with these data and calculations have been performed for 165 keV/u and 506 keV/u C 6+ +He to compare results for the same q/v perturbation strengths. (orig.)

Central Au on Au collisions

Energy Technology Data Exchange (ETDEWEB)

Alard, J.P.; Amouroux, V. [Labo de Phys. Corp., IN2P3-CRNS, Univ. Blaise Pascal, Clermont-Fd. (France); Basrak, Z. [Rudjer Boskovic Institute, Zagreb (Croatia)] [and others; FOPI-Collaboration

1995-02-06

In nucleus-nucleus collisions the initial relative kinetic energy of target and projectile is available for internal excitation of the interacting system; it is however still not well established to what extent local equilibrium and thermalisation occur. Local equilibrium is of interest to derive, within the formalism of transport equations and of the equation of state, (EOS), general properties of compressed and excited nuclear matter. Such approach describes in relatively simple terms the complex many body interactions occuring within extended baryonic and hadronic (or quark) matter. For a basic microscopic understanding it is highly desirable to investigate the elementary in-medium interactions in relation to the free elementary processes. Excitation function measurements of central collisions between the heaviest available nuclei (like Au on Au), supply the best ground for such studies: the highest degree of thermalisation and compression is expected for such reactions. The consideration presented here of energy thermalisation and of an expanding system clusterizing at freeze-out in a situation close to the liquid gas phase transition can be of interest to astrophysics as well as to the quark gluon plasma deconfinement studied in nucleus-nucleus collisions at the higher energy regime of CERN and Brookhaven. (orig.).

The origin of small and large molecule behavior in the vibrational relaxation of highly excited molecules

International Nuclear Information System (INIS)

Gordon, R.J.

1990-01-01

An explanation is proposed for the qualitatively different types of behavior that have been reported for the vibrational relaxation of highly excited diatomic and polyatomic molecules. It is argued that all of the diatomic molecules that have been studied in bulk relax adiabatically at room temperature. In contrast, large polyatomic molecules have low frequency modes which act at ''doorway'' modes for the rest of the molecules, producing an impulsive relaxation mechanism. The theoretical work of Nesbitt and Hynes showed that impulsive collisions result in an exponential decay of the average vibrational energy of a Morse oscillator, whereas adiabatic collisions produce nonexponential power law behavior. We propose that this result explains a large body of data for the vibrational relaxation of small and large molecules

Electron-positron pair creation in heavy ion collisions

International Nuclear Information System (INIS)

Kienle, P.

1987-01-01

The authors review the status of experiments to study the electron positron pair creation in heavy ion atom collisions at bombarding energies close to the Coulomb barrier. The disentanglement and characterization of various sources of positrons observed in such collisions are described with a focus on the monoenergetic electron positron pairs observed. They seem to originate from the two-body decay of a family of neutral particles with masses of about 3m and lifetimes in the range of 6 x 10 - 14 s, produced by high Coulomb fields. First attempts were made to create these particles by resonant Bhabha scattering

Spectra of identified particles, geometry categorization and bias and global observables in d+Au collisions

Energy Technology Data Exchange (ETDEWEB)

Campbell, Sarah

2014-11-15

Geometry selection in d+Au/p+Pb collisions is crucial for understanding the physics underlying modified nuclear parton distribution functions, gluon saturation or shadowing, initial state energy loss, and possible hydrodynamic flow in these small systems. The PHENIX Collaboration tests for auto-correlation biases in the geometry determination in small collision systems. These biases are well understood and an order of magnitude smaller at RHIC as compared to the LHC. As a result, auto-correlation biases are unable to describe the suppression of high transverse momentum (p{sub T}) π{sup 0}'s seen in the ratio of central-to-peripheral d+Au collisions. The centrality dependent d+Au pion, kaon and proton yields relative to binary collision-scaled p+p yields are also reported, including the high p{sub T}π{sup 0} and K{sub S}{sup 0}. At intermediate p{sub T}, between 2and5GeV/c, baryons are enhanced in central d+Au collisions. The baryon enhancement is present in d+Au and Au+Au collisions and increases with centrality. We compare identified particle yields in peripheral Au+Au collisions to central d+Au collisions that have a comparable number of participants and binary collisions. The p{sub T} dependence of this ratio is strikingly similar for mesons and baryons.

A new theory of collisions

International Nuclear Information System (INIS)

Giraud, B.G.

1989-01-01

Instead of diagonalizing the many-body Hamiltonian H, we invert E-H, where E is a complex energy, eventually real. All the traditional approximations to diagonalization can be adjusted to inversion. We specially investigate mean-field methods. This lecture gives a scheme for the detailed proofs of our arguments, already published, and lists several numerically soluble cases where our new method has been successfully tested for the calculation of collision amplitudes

Intelligent landing strategy for the small bodies: from passive bounce to active trajectory control

Science.gov (United States)

Cui, Pingyuan; Liu, Yanjie; Yu, Zhengshi; Zhu, Shengying; Shao, Wei

2017-08-01

Landing exploration is an important way to improve the understanding of small bodies. Considering the weak gravity field as well as the strict attitude constraints which make bounce a common situation and a tough issue for safe landing on small bodies, a novel active trajectory control-based intelligent landing strategy is proposed to improve the safety and reliability of mission. The scenarios of intelligent landing strategy for both safe landing and hopping exploration are introduced in detail and a potential structure for autonomous navigation and control system is presented. Furthermore, a convex optimization-based control algorithm is developed, which is the key technology fulfilling the active trajectory control. Meanwhile a novel discretization method based on the fourth-order Runge-Kutta rule is proposed to improve the accuracy. A helpful adjustment process of time-to-landing is also introduced when the feasible trajectory does not exist. Comprehensive simulations about the proposed intelligent landing strategy are performed to demonstrate the improved safety and accuracy of both landing and hopping exploration on small bodies. Meanwhile, the performance and accuracy of the proposed convex optimization-based control algorithms is also compared and discussed thoroughly. Some useful conclusions for control system design are also obtained.

Electron-positron pair creation in heavy ion collisions

International Nuclear Information System (INIS)

Kienle, P.

1987-08-01

We review here the status of experiments to study the electron positron pair creation in heavy ion atom collisions at bombarding energies close to the Coulomb barrier. The disentanglement and characterisation of various sources of positrons observed in such collisions are described with a focus on the monoenergetic electron positron pairs observed. They seem to originate from the two-body decay of a family of neutral particles with masses of about 3 m e and life times in the range of 6x10 -14 s -10 s, produced by high Coulomb fields. First attempts were made to create these particles by resonant Bhabha scattering. First we present some experimental methods for high efficiency positron spectroscopy in heavy ion collisions. Then we describe the discovery of positron creation induced by strong time changing Coulomb fields. (orig./HSI)

Modern Estimation Techniques and Optimal Maneuver Targeting for Autonomous Optical Navigation around Small Bodies

Data.gov (United States)

National Aeronautics and Space Administration — Autonomous Optical Navigation (AON) allows for significant advances in spacecraft navigation accuracy around small bodies located far from Earth, such as asteroids...

Two-body similarity and its violation in tokamak edge plasmas

International Nuclear Information System (INIS)

Catto, P.J.; Knoll, D.A.; Krasheninnikov, S.I.

1996-01-01

Scaling laws found under the assumption that two-body collisions dominate can be effectively used to benchmark complex multi-dimensional codes dedicated to investigating tokamak edge plasmas. The applicability of such scaling laws to the interpretation of experimental data, however, is found to be restricted to the relatively low plasma densities ( 19 m -3 ) at which multistep processes, which break the two-body collision approximation, are unimportant. copyright 1996 American Institute of Physics

Algal Diet of Small-Bodied Crustacean Zooplankton in a Cyanobacteria-Dominated Eutrophic Lake.

Directory of Open Access Journals (Sweden)

Ilmar Tõnno

Full Text Available Small-bodied cladocerans and cyclopoid copepods are becoming increasingly dominant over large crustacean zooplankton in eutrophic waters where they often coexist with cyanobacterial blooms. However, relatively little is known about their algal diet preferences. We studied grazing selectivity of small crustaceans (the cyclopoid copepods Mesocyclops leuckarti, Thermocyclops oithonoides, Cyclops kolensis, and the cladocerans Daphnia cucullata, Chydorus sphaericus, Bosmina spp. by liquid chromatographic analyses of phytoplankton marker pigments in the shallow, highly eutrophic Lake Võrtsjärv (Estonia during a seasonal cycle. Copepods (mainly C. kolensis preferably consumed cryptophytes (identified by the marker pigment alloxanthin in gut contents during colder periods, while they preferred small non-filamentous diatoms and green algae (identified mainly by diatoxanthin and lutein, respectively from May to September. All studied cladoceran species showed highest selectivity towards colonial cyanobacteria (identified by canthaxanthin. For small C. sphaericus, commonly occuring in the pelagic zone of eutrophic lakes, colonial cyanobacteria can be their major food source, supporting their coexistence with cyanobacterial blooms. Pigments characteristic of filamentous cyanobacteria and diatoms (zeaxanthin and fucoxanthin, respectively, algae dominating in Võrtsjärv, were also found in the grazers' diet but were generally avoided by the crustaceans commonly dominating the zooplankton assemblage. Together these results suggest that the co-occurring small-bodied cyclopoid and cladoceran species have markedly different algal diets and that the cladocera represent the main trophic link transferring cyanobacterial carbon to the food web in a highly eutrophic lake.

Proton capture and loss in ion-molecule collisions

International Nuclear Information System (INIS)

Ibanez, S; Alessi, M; Zimmerman, V; Fregenal, D; Focke, P; Bernardi, G; Suarez, S

2007-01-01

We have measured proton distributions from the collision systems Ar + , Kr + on CH 4 molecular targets, searching for atom capture into the projectile continuum. Within the studied energy range (100 to 300 eV/u) we have not distinctive evidence of capture. A small contamination of ion beams with molecular ions as ArH + or KrH + , have shown to be enough to produce peak shaped structures at the projectile velocity. We, therefore, concentrate our study on proton loss from molecular ions in collision with several targets

Analysis of a ship-to-ship collision

International Nuclear Information System (INIS)

Porter, V.L.; Ammerman, D.J.

1996-01-01

Sandia National Laboratories is involved in a safety assessment for the shipment of radioactive material by sea. One part of this study is investigation of the consequences of ship-to-ship collisions. This paper describes two sets of finite element analyses performed to assess the structural response of a small freighter and the loading imparted to radioactive material (RAM) packages during several postulated collision scenarios with another ship. The first series of analyses was performed to evaluate the amount of penetration of the freighter hull by a striking ship of various masses and initial velocities. Although these analyses included a representation of a single RAM package, the package was not impacted during the collision so forces on the package could not be computed. Therefore, a second series of analyses incorporating a representation of a row of seven packages was performed to ensure direct package impact by the striking ship. Average forces on a package were evaluated for several initial velocities and masses of the striking ship. In addition to. providing insight to ship and package response during a few postulated ship collisions scenarios, these analyses will be used to benchmark simpler ship collision models used in probabilistic risk assessment analyses

An accurate nonlinear Monte Carlo collision operator

International Nuclear Information System (INIS)

Wang, W.X.; Okamoto, M.; Nakajima, N.; Murakami, S.

1995-03-01

A three dimensional nonlinear Monte Carlo collision model is developed based on Coulomb binary collisions with the emphasis both on the accuracy and implementation efficiency. The operator of simple form fulfills particle number, momentum and energy conservation laws, and is equivalent to exact Fokker-Planck operator by correctly reproducing the friction coefficient and diffusion tensor, in addition, can effectively assure small-angle collisions with a binary scattering angle distributed in a limited range near zero. Two highly vectorizable algorithms are designed for its fast implementation. Various test simulations regarding relaxation processes, electrical conductivity, etc. are carried out in velocity space. The test results, which is in good agreement with theory, and timing results on vector computers show that it is practically applicable. The operator may be used for accurately simulating collisional transport problems in magnetized and unmagnetized plasmas. (author)

Transport coefficients of multi-particle collision algorithms with velocity-dependent collision rules

International Nuclear Information System (INIS)

Ihle, Thomas

2008-01-01

Detailed calculations of the transport coefficients of a recently introduced particle-based model for fluid dynamics with a non-ideal equation of state are presented. Excluded volume interactions are modeled by means of biased stochastic multi-particle collisions which depend on the local velocities and densities. Momentum and energy are exactly conserved locally. A general scheme to derive transport coefficients for such biased, velocity-dependent collision rules is developed. Analytic expressions for the self-diffusion coefficient and the shear viscosity are obtained, and very good agreement is found with numerical results at small and large mean free paths. The viscosity turns out to be proportional to the square root of temperature, as in a real gas. In addition, the theoretical framework is applied to a two-component version of the model, and expressions for the viscosity and the difference in diffusion of the two species are given

Evaluating the biological potential in samples returned from planetary satellites and small solar system bodies: framework for decision making

National Research Council Canada - National Science Library

National Research Council Staff; Space Studies Board; Division on Engineering and Physical Sciences; National Research Council; National Academy of Sciences

... from Planetary Satellites and Small Solar System Bodies Framework for Decision Making Task Group on Sample Return from Small Solar System Bodies Space Studies Board Commission on Physical Sciences, Mathematics, and Applications National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1998 i Copyrightthe true use are Please breaks...

Multiplicity fluctuations and collective flow in small colliding systems

Science.gov (United States)

Kawaguchi, Koji; Murase, Koichi; Hirano, Tetsufumi

2017-11-01

Recent observation of collective-flow-like behaviours in small colliding systems attracts significant theoretical and experimental interests. In large colliding systems, large collective flow has been interpreted as manifestation of almost-perfect fluidity of the quark gluon plasma (QGP). So it is quite intriguing to explore how small the QGP can be as a fluid. Multiplicity fluctuations play a crucial role in centrality definition of the events in small colliding systems since the fluctuations are, in general, more important as the system size is getting smaller. To consider the correct multiplicity fluctuations, we employ PYTHIA which naturally describes multiplicity distribution in p+p collisions. We superpose p+p collisions by taking into account the number of participants and that of binary collisions from Monte-Carlo version of Glauber model and evaluate initial entropy density distributions which contain not only multiplicity fluctuations but also fluctuations of longitudinal profiles. Solving hydrodynamic equations followed by the hadronic afterburner, we calculate transverse momentum spectra, elliptic and triangular flow parameters in p+Au, d+Au and 3He+Au collisions at the RHIC energy and p+Pb collisions at the LHC energy. Although a large fraction of final anisotropic flow parameters comes from the fluid-dynamical stage, the effects of hadronic rescatterings turn out to be also important as well in understanding of the flow data in small colliding systems.

On the global ship hull bending energy in ship collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Li, Yujie

2009-01-01

During ship collisions part of the kinetic energy of the involved vessels immediately prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can...... be stored in elastic hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non-trivial part of the energy released for structural deformation during the collision can be absorbed as elastic...... energy in global ship hull vibrations, such that with strong ship sides less energy has to be spent in crushing of the striking ship bow and/or the struck ship side. In normal ship–ship collision analyses both the striking and struck ship are usually considered as rigid bodies where structural crushing...

Dissipation in nucleus-nucleus collisions

International Nuclear Information System (INIS)

Santanu Pal

1984-01-01

This paper deals with the mechanism of one- and two-body dissipations in nucleus-nucleus collisions. The average energy transferred to nuclear excitations is calculated using a time-dependent density matrix approach with lowest-order approximations. Considering the nuclei as Fermi gases, and using a gaussian-type NN interaction as the basic perturbation, simplified expressions are obtained for energy dissipations. These expressions are quite instructive to follow a number of interesting aspects of one- and two-body dissipations. It is theoretically observed that the memory time for the two-body dissipation is significantly smaller than that of one-body dissipation. A threshold-type dependence of the transferred energy on the relative velocity between the two nuclei is also observed. This threshold velocity is found to be related with the intrinsic nucleon kinetic energy for two-body dissipation and with the nuclear size for the one-body case. This observation further suggests that the total dissipated energy is shared between the two nuclei approximately in the ratio of their masses. The physical origin of these observations is also explained. Numerical calculations further illustrate some characteristic features of one- and two-body dissipations. (orig.)

Multivariable hypergeometric functions for ion-atom collisions

Energy Technology Data Exchange (ETDEWEB)

Gasaneo, G.; Colavecchia, F.D.; Garibotti, C.R

1999-06-03

In this work we present a correlated wave function for a three-body continuum Coulomb problem. This state is described by the two-variables PHI{sub 2} hypergeometric function. We examine the properties of this function and their differences with previous uncorrelated models. The PHI{sub 2} wave function can be considered as a final state of ion-atom ionizing collisions, giving rise to both undistorted (Born-PHI{sub 2}) and distorted (EIS-PHI{sub 2}) models. We obtain double differential cross sections with the Born-PHI{sub 2} theory for proton-helium collisions in the intermediate to high energy regime. They exhibit all the main features of the electronic emission process and agree with the experimental data.

Recent Results on Multi-Particle Azimuthal Correlations in High-Multiplicity pp and pPb Collisions in CMS

CERN Document Server

Bernardes, Cesar Augusto

2017-01-01

In nucleus-nucleus collisions, the Quark-Gluon Plasma behaves like a perfect fluid and the azimuthal anisotropy of the observed particle final-state distributions reflects its properties. This anisotropic flow, arising mainly from initial-state geometry and its fluctuations, highlights the collective behavior of the particles produced in the collision. It is well-described by hydrodynamics and explains the long-range near-side correlations, known as the ridge, observed experimentally in AA collisions and, more recently, in small systems such as pp or pA collisions. The CMS experiment has studied this correlation in details by extracting the momenta of the Fourier decomposition of azimuthal particle-distribution in the final state ($v_{\\mathrm{n}}$, n = 2 - 4). The $v_{\\mathrm{n}}$ are extracted using di-hadron correlation and multi-particle cumulant methods in both pp and pPb collisions. In this talk, results from CMS on the ridge in small systems are shown and compared with those in PbPb collisions, demonstr...

General description of few-body break-up processes at threshold

International Nuclear Information System (INIS)

Barrachina, R.O.

2005-01-01

In this communication we describe the effects produced by an N-body threshold behavior in N + 1 body break-up processes, as it occurs in situations where one of the fragments acquires almost all the excess energy of the system. Furthermore, we relate the appearance of discontinuities in single-particle multiply differential cross sections to the threshold behavior of the remaining particles, and describe the applicability of these ideas to different systems from atomic, molecular and nuclear collision physics. We finally show that, even though the study of ultracold collisions represents the direct way of gathering information on a break-up system near threshold, the analysis of high-energy collisions provides an alternative, and sometimes advantageous, approach

General description of few-body break-up processes at threshold

International Nuclear Information System (INIS)

Barrachina, R.O.

2004-01-01

Full text: In this communication we present a general description of the behavior of fragmentation processes near threshold by analyzing the break-up into two, three and N bodies in steps of increasing complexity. In particular, we describe the effects produced by an N-body threshold behavior in N+1 body break-up processes, as it occurs in situations where one of the fragments acquires almost all the excess energy of the system. Furthermore, we relate the appearance of cusps and discontinuities in single-particle multiply differential cross sections to the threshold behavior of the remaining particles, and apply these ideas to different systems from atomic, molecular and nuclear collision physics. We finally show that, even though the study of ultracold collisions represents the direct way of gathering information on a break-up system near threshold, the analysis of high-energy collisions provides an alternative, and sometimes advantageous, approach

HIGH ECLIPTIC LATITUDE SURVEY FOR SMALL MAIN-BELT ASTEROIDS

International Nuclear Information System (INIS)

Terai, Tsuyoshi; Takahashi, Jun; Itoh, Yoichi

2013-01-01

Main-belt asteroids have been continuously colliding with one another since they were formed. Their size distribution is primarily determined by the size dependence of asteroid strength against catastrophic impacts. The strength scaling law as a function of body size could depend on collision velocity, but the relationship remains unknown, especially under hypervelocity collisions comparable to 10 km s –1 . We present a wide-field imaging survey at an ecliptic latitude of about 25° for investigating the size distribution of small main-belt asteroids that have highly inclined orbits. The analysis technique allowing for efficient asteroid detections and high-accuracy photometric measurements provides sufficient sample data to estimate the size distribution of sub-kilometer asteroids with inclinations larger than 14°. The best-fit power-law slopes of the cumulative size distribution are 1.25 ± 0.03 in the diameter range of 0.6-1.0 km and 1.84 ± 0.27 in 1.0-3.0 km. We provide a simple size distribution model that takes into consideration the oscillations of the power-law slope due to the transition from the gravity-scaled regime to the strength-scaled regime. We find that the high-inclination population has a shallow slope of the primary components of the size distribution compared to the low-inclination populations. The asteroid population exposed to hypervelocity impacts undergoes collisional processes where large bodies have a higher disruptive strength and longer lifespan relative to tiny bodies than the ecliptic asteroids

Stereotactic Body Radiotherapy for Centrally Located Non-small Cell Lung Cancer

Directory of Open Access Journals (Sweden)

Yuming WAN

2018-05-01

Full Text Available A few study has proven that about 90% of local control rates might be benefit from stereotactic body radiotherapy (SBRT for patients with medically inoperable stage I non-small cell lung cancer (NSCLC, it is reported SBRT associated overall survival and tumor specific survival is comparable with those treated with surgery. SBRT has been accepted as the first line treatment for inoperable patients with peripheral located stage I NSCLC. However, the role of SBRT in centrally located lesions is controversial for potential toxic effects from the adjacent anatomical structure. This paper will review the definition, indication, dose regimens, dose-volume constraints for organs at risk, radiation technology, treatment side effect of centrally located NSCLC treated with SBRT and stereotactic body proton therapy.

Six Degrees-of-Freedom Ascent Control for Small-Body Touch and Go

Science.gov (United States)

Blackmore, Lars James C.

2011-01-01

A document discusses a method of controlling touch and go (TAG) of a spacecraft to correct attitude, while ensuring a safe ascent. TAG is a concept whereby a spacecraft is in contact with the surface of a small body, such as a comet or asteroid, for a few seconds or less before ascending to a safe location away from the small body. The report describes a controller that corrects attitude and ensures that the spacecraft ascends to a safe state as quickly as possible. The approach allocates a certain amount of control authority to attitude control, and uses the rest to accelerate the spacecraft as quickly as possible in the ascent direction. The relative allocation to attitude and position is a parameter whose optimal value is determined using a ground software tool. This new approach makes use of the full control authority of the spacecraft to correct the errors imparted by the contact, and ascend as quickly as possible. This is in contrast to prior approaches, which do not optimize the ascent acceleration.

Cascade statistics in the binary collision approximation and in full molecular dynamics

International Nuclear Information System (INIS)

Hou, M.; Pan, Z.Y.

1995-01-01

The Binary Collision Approximation (BCA) and Molecular Dynamics (MD) are used to simulate low energy atomic collision cascades in solids. Results are compared and discussed on the example of copper and gold self irradiation. For MD, long range N-body potentials are built, similar to those deduced from the second moment semi-empirical tight binding model. The pair interaction contribution is splined to a Moliere screened Coulomb potential at small separation distances. The BCA calculations are performed with the MARLOWE program, using the same Moliere potential as for MD, and modelling the N-body contribution by a binding of the atoms to their equilibrium lattice sites. The scattering integrals are estimated by means of a 4 points Gauss-Mehler quadrature. In MD, the NVT equations of motion are integrated with a constant time step of 2 fs. For the NVE cascade simulations, the Newton equations of motion are solved with a dynamically adjusted time step, kept lower than 2 fs. The influence of the time step on the simulated trajectories is discussed. The mean number of moving atoms with total energy above threshold values ranging from 1 to 100 eV is estimated as a function of time over 300 fs both with MARLOWE and by MD. This estimate is repeated for external primary energies ranging from 250 eV to 1 keV. In the case of copper, the BCA results are found to be in remarkable agreement with MD over about 200 fs cascade development, provided the size of the crystallite used in MD is sufficiently large in order to account for the early mechanical response of the close environment. This agreement between the two methods is found to be the best when the binding energy of the target atoms as modelled in the BCA is adjusted to a value close to the cohesive energy. In the case of gold, the agreement between BCA and MD is reasonable and the results suggest the need of an accurate modelling of linear collision sequences in the BCA. (orig.)

Rearrangement reactions in ion-ion and ion-atom collisions: results and problems

Energy Technology Data Exchange (ETDEWEB)

Presnyakov, L.P. [Lebedev Physical Institute, Moscow (Russian Federation); Tawara, H.

1997-01-01

Recent experimental and theoretical results are discussed for ionic collisions with large cross sections at intermediate and small energies of the relative motion. Single- and double-electron removal from H{sup -} ions in slow collisions with other ions is considered in more details. The theoretical methods are discussed from the viewpoint of general requirements of scattering theory. (author)

Mechanisms of High Energy Hadron-Nucleus and Nucleus-Nucleus Collision Processes

International Nuclear Information System (INIS)

Strugalski, Z.

1994-01-01

Mechanisms of high energy hadron-nucleus and nucleus-nucleus collision processes are depicted qualitatively, as prompted experimentally. In hadron-nucleus collisions the interaction of the incident hadron in intranuclear matter is localized in small cylindrical volume, with the radius as large as the strong interaction range is, centered on the hadron course in the nucleus. The nucleon emission is induced by the hadron in its passing through the nucleus; particles are produced via intermediate objects produced in 2 → 2 endoergic reactions of the hadron and its successors with downstream nucleons. In nucleus-nucleus collisions, the outcome of the reaction appears as the composition of statistically independent hadron-nucleus collision outcomes at various impact parameters. Observable effects supporting such mechanisms are discussed. 51 refs

On the Global Ship Hull Bending Energy in Ship Collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Li, Y.

2004-01-01

During ship collisions part of the kinetic energy of the involved vessels prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can be stored in elastic...... hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non trivial part of the energy released for structural deformation during the collision can be absorbed as elastic energy in global...... ship hull vibrations, such that with strong ship sides less energy has to be spent in crushing of the striking ship bow and/or the struck ship side. In normal ship-ship collision analyses both the striking and struck ship are usually considered as rigid bodies where structural crushing is confined...

Electron detachment by H- + H- collisions

International Nuclear Information System (INIS)

Chibisov, M.I.; Yavlinskii, Yu.N.

1994-01-01

The autoionization channels for electrons detachment in collisions of two negative hydrogen ions in the energy range 300 - 500 eV and > 500 eV are investigated. In small energy range at large inter-ion distances the asymptotic approximation is used; at high energies - perturbation theory and classical motion are used. 18 refs., 3 figs

The integral first collision kernel method for gamma-ray skyshine analysis[Skyshine; Gamma-ray; First collision kernel; Monte Carlo calculation

Energy Technology Data Exchange (ETDEWEB)

Sheu, R.-D.; Chui, C.-S.; Jiang, S.-H. E-mail: shjiang@mx.nthu.edu.tw

2003-12-01

A simplified method, based on the integral of the first collision kernel, is presented for performing gamma-ray skyshine calculations for the collimated sources. The first collision kernels were calculated in air for a reference air density by use of the EGS4 Monte Carlo code. These kernels can be applied to other air densities by applying density corrections. The integral first collision kernel (IFCK) method has been used to calculate two of the ANSI/ANS skyshine benchmark problems and the results were compared with a number of other commonly used codes. Our results were generally in good agreement with others but only spend a small fraction of the computation time required by the Monte Carlo calculations. The scheme of the IFCK method for dealing with lots of source collimation geometry is also presented in this study.

A new and simple extraction technique for rectal foreign bodies: removing by cutting into small pieces

OpenAIRE

Abbas Aras; Mehmet Karabulut; Osman Kones; Kaplan Baha Temizgonul; Halil Alis

2014-01-01

The purposes of insertion and types of foreign bodies in rectum show great variation. Rectal foreign bodies need to be removed without giving damage to intestinal wall and this should be done in the easiest possible way. We have reported a new and a simple technique. It is easy to apply and safe. A patient was admitted to our clinic with a rectal foreign body (radish) which was successfully removed by cutting it into small pieces. We conclude that different kinds of rectal foreign bodies, esp...

Lightwave-driven quasiparticle collisions on a subcycle timescale.

Science.gov (United States)

Langer, F; Hohenleutner, M; Schmid, C P; Poellmann, C; Nagler, P; Korn, T; Schüller, C; Sherwin, M S; Huttner, U; Steiner, J T; Koch, S W; Kira, M; Huber, R

2016-05-12

Ever since Ernest Rutherford scattered α-particles from gold foils, collision experiments have revealed insights into atoms, nuclei and elementary particles. In solids, many-body correlations lead to characteristic resonances--called quasiparticles--such as excitons, dropletons, polarons and Cooper pairs. The structure and dynamics of quasiparticles are important because they define macroscopic phenomena such as Mott insulating states, spontaneous spin- and charge-order, and high-temperature superconductivity. However, the extremely short lifetimes of these entities make practical implementations of a suitable collider challenging. Here we exploit lightwave-driven charge transport, the foundation of attosecond science, to explore ultrafast quasiparticle collisions directly in the time domain: a femtosecond optical pulse creates excitonic electron-hole pairs in the layered dichalcogenide tungsten diselenide while a strong terahertz field accelerates and collides the electrons with the holes. The underlying dynamics of the wave packets, including collision, pair annihilation, quantum interference and dephasing, are detected as light emission in high-order spectral sidebands of the optical excitation. A full quantum theory explains our observations microscopically. This approach enables collision experiments with various complex quasiparticles and suggests a promising new way of generating sub-femtosecond pulses.

State-to-state dynamics of H+HX collisions. II. The H+HX→HX/sup dagger/+H (X = Cl,Br,I) reactive exchange and inelastic collisions at 1.6 eV collision energy

International Nuclear Information System (INIS)

Aker, P.M.; Germann, G.J.; Tabor, K.D.; Valentini, J.J.

1989-01-01

We report measurement of product state distributions for the rotationally and/or vibrationally excited HX formed in collisions of translationally hot H atoms with HX (X = Cl, Br, and I) at 1.6 eV collision energy. The product state distributions are probed after only one collision of the fast H atom, using coherent anti-Stokes Raman scattering spectroscopy. Whether proceeding by inelastic collisions or reactive exchange, the transfer of translational energy to vibrational and rotational energy is quite inefficient in H+HX collisions at 1.6 eV. For all three hydrogen halides only 2--3% of the initial translational energy appears as HX vibration. For H+HCl only 6% of the initial energy is converted to HCl rotational energy, while for H+HBr and H+HI, this percentage is twice as large, 11--12%, but still small. The indistinguishability of the two H atoms involved makes it impossible to distinguish reactive exchange from inelastic energy transfer in these H+HX collisions. However, the difference in rotational energy partitioning for H+HBr and H+HI as compared with H+HCl, suggests that reactive exchange is dominant in the former and inelastic energy transfer dominates in the latter. The total cross sections for the combined energy transfer/reactive exchange do not change much with the identity of X, being 13 +- 3, 11 +- 2, and 11 +- 2 A 2 , for H+HCl, H+HBr, and H+HI, respectively

From many body wee partons dynamics to perfect fluid: a standard model for heavy ion collisions

Energy Technology Data Exchange (ETDEWEB)

Venugopalan, R.

2010-07-22

We discuss a standard model of heavy ion collisions that has emerged both from experimental results of the RHIC program and associated theoretical developments. We comment briefly on the impact of early results of the LHC program on this picture. We consider how this standard model of heavy ion collisions could be solidified or falsified in future experiments at RHIC, the LHC and a future Electro-Ion Collider.

The dynamics of milk droplet-droplet collisions

Science.gov (United States)

Finotello, Giulia; Kooiman, Roeland F.; Padding, Johan T.; Buist, Kay A.; Jongsma, Alfred; Innings, Fredrik; Kuipers, J. A. M.

2018-01-01

Spray drying is an important industrial process to produce powdered milk, in which concentrated milk is atomized into small droplets and dried with hot gas. The characteristics of the produced milk powder are largely affected by agglomeration, combination of dry and partially dry particles, which in turn depends on the outcome of a collision between droplets. The high total solids (TS) content and the presence of milk proteins cause a relatively high viscosity of the fed milk concentrates, which is expected to largely influence the collision outcomes of drops inside the spray. It is therefore of paramount importance to predict and control the outcomes of binary droplet collisions. Only a few studies report on droplet collisions of high viscous liquids and no work is available on droplet collisions of milk concentrates. The current study therefore aims to obtain insight into the effect of viscosity on the outcome of binary collisions between droplets of milk concentrates. To cover a wide range of viscosity values, three milk concentrates (20, 30 and 46% TS content) are investigated. An experimental set-up is used to generate two colliding droplet streams with consistent droplet size and spacing. A high-speed camera is used to record the trajectories of the droplets. The recordings are processed by Droplet Image Analysis in MATLAB to determine the relative velocities and the impact geometries for each individual collision. The collision outcomes are presented in a regime map dependent on the dimensionless impact parameter and Weber ( We) number. The Ohnesorge ( Oh) number is introduced to describe the effect of viscosity from one liquid to another and is maintained constant for each regime map by using a constant droplet diameter ( d ˜ 700 μ m). In this work, a phenomenological model is proposed to describe the boundaries demarcating the coalescence-separation regimes. The collision dynamics and outcome of milk concentrates are compared with aqueous glycerol

Memory effects in dissipative nucleus-nucleus collision

International Nuclear Information System (INIS)

Yadav, H.L.; Agarwal, K.C.

2002-01-01

A macroscopic dynamical model within the framework of a multidimensional Fokker-Planck equation is employed for a theoretical description of low-energy dissipative collisions between two heavy nuclei. The effect of two-body collisions leading to intrinsic equilibrium has been treated phenomenologically using the basic concepts of dissipative diabatic dynamics. The heavy-ion reaction 86 Kr(8.18 MeV/u) + 166 Er has been as a prototype to study and demonstrate the memory effects for dissipation and diffusion processes. Our calculated results for the deflection angle, angular distributions dσ/dθ cm , energy distributions dσ/dΔΕ, and element distributions dσ/dΖ illustrate a remarkable dependence on the memory effects and are consistent with the experimental data

Correlations of neutral pions in ultrarelativistic heavy ion collisions

International Nuclear Information System (INIS)

Peitzmann, T.; Beckmann, P.; Berger, F.; Glewing, G.; Dragon, L.; Glasow, R.; Kampert, K.H.; Loehner, H.; Purschke, M.; Santo, R.; Albrecht, R.; Bock, R.; Claesson, G.; Gutbrod, H.H.; Kolb, B.W.; Lund, I.; Schmidt, H.R.; Siemiarczuk, T.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Lee, I.Y.; Obenshain, F.E.; Plasil, F.; Soerensen, S.P.; Young, G.R.; Eklund, A.; Garpman, S.; Gustafsson, H.A.; Idh, J.; Kristiansson, P.; Oskarsson, A.; Otterlund, I.; Persson, S.; Stenlund, E.; Franz, A.; Poskanzer, A.M.; Ritter, H.G.

1989-01-01

Correlations of 4 photons representing neutral pions have been studied in ultrarelativistic heavy ion collisions. Data were taken in the WA80 experiment at the CERN-SPS with a 200 A GeV oxygen beam. The π 0 are detected via their decay photons with a high-granularity lead glass array. Special features of interferometry using neutral pions will be discussed. The extracted preliminary parameters for high p T pions emitted near midrapidity in O+Au collisions lead to rather small effective source sizes. (orig.)

Pedestrian-motorcycle collisions: associated risks and issues

Directory of Open Access Journals (Sweden)

Ariffin Aqbal Hafeez

2017-01-01

Full Text Available From the statistics, there are serious concerns over the relatively high number of fatal motor vehicle crashes involving pedestrianmotorcycle in Malaysia. The high number of motorcycle registration on road, compounded by its popularity as the major mode of transportation in the nation, imposes safety risk to pedestrians, as well as to other road users. Data from 1,626 related road crashes of Royal Malaysia Police (RMP for the 2009-2013 period were retrospectively collected via MIROS Road Accident Analysis and Database System (M-ROADS. The data were then analyzed via logistic regression method to determine associations between risks and injury severity in pedestrian-motorcycle collisions. The results indicate that five factors were significantly related to injury severity, which include age, location of body injury, as well as speed limit, road geometry and lighting condition of collision site. Subsequently, focus group discussions with stakeholders were also conducted to gather relevant data to identify related issues and suggestions on motorcycle safety technology with regards to collision with pedestrian.

Dynamics of the water dimer + nitric oxide collision

Energy Technology Data Exchange (ETDEWEB)

Ree, Jong Baik [Dept. of Chemistry Education, Chonnam National University, Gwangju (Korea, Republic of); Kim, Yoo Hang [Dept. of Chemistry, Inha University, Incheon (Korea, Republic of); Shin, Hyung Kyu [Dept. of Chemistry, University of Nevada, Nevada (Korea, Republic of)

2017-02-15

Collision-induced intermolecular energy transfer and intramolecular vibrational redistribution in the collision of a water dimer and nitric oxide are studied by use of quasiclassical procedures. Intermolecular energy flow is shown to occur mainly through a direct-mode mechanism transferring relatively large amounts in strong collisions. About a quarter of the energy initially deposited in the dimer transfers to the ground state NO, while the rest redistributes among internal motions of the collision system. The main portion of initial energy deposited in the dimer redistributes in the stretches of the donor monomer through the 1:1 resonance followed by in the bend through the 1:2 resonance. Energy transfer from the excited NO to the ground-state dimer is equally efficient, transferring more than half the initial excitation to the donor monomer, the efficiency that is attributed to the internal modes operating as energy reservoirs. The hydrogen bond shares about 15% of the initial excitation stored in both dimer-to-NO and NO-to-dimer processes as a result of strong coupling of the hydrogen bond with the proton-donor OH bond of the monomer. A small fraction of collisions proceeds through a complex-mode mechanism and lead to NO dissociation, the dissociated O atom showing a propensity to form a new hydrogen bond.

Simulation Methods in the Contact with Impact of Rigid Bodies

Directory of Open Access Journals (Sweden)

Cristina Basarabă-Opritescu

2007-10-01

Full Text Available The analysis of impacts of elastic bodies is topical and it has many applications, practical and theoretical, too. The elastic character of collision is put in evidence, especially by the velocities of some parts of a particular body, named “ring”. In the presented paper, the situation of elastic collisions is put in evidence by the simulation with the help of the program ANSYS and it refers to the particular case of the ring, with the mechanical characteristics, given in the paper

The Suborbital Particle Aggregation and Collision Experiment (SPACE): studying the collision behavior of submillimeter-sized dust aggregates on the suborbital rocket flight REXUS 12.

Science.gov (United States)

Brisset, Julie; Heißelmann, Daniel; Kothe, Stefan; Weidling, René; Blum, Jürgen

2013-09-01

The Suborbital Particle Aggregation and Collision Experiment (SPACE) is a novel approach to study the collision properties of submillimeter-sized, highly porous dust aggregates. The experiment was designed, built, and carried out to increase our knowledge about the processes dominating the first phase of planet formation. During this phase, the growth of planetary precursors occurs by agglomeration of micrometer-sized dust grains into aggregates of at least millimeters to centimeters in size. However, the formation of larger bodies from the so-formed building blocks is not yet fully understood. Recent numerical models on dust growth lack a particular support by experimental studies in the size range of submillimeters, because these particles are predicted to collide at very gentle relative velocities of below 1 cm/s that can only be achieved in a reduced-gravity environment. The SPACE experiment investigates the collision behavior of an ensemble of silicate-dust aggregates inside several evacuated glass containers which are being agitated by a shaker to induce the desired collisions at chosen velocities. The dust aggregates are being observed by a high-speed camera, allowing for the determination of the collision properties of the protoplanetary dust analog material. The data obtained from the suborbital flight with the REXUS (Rocket Experiments for University Students) 12 rocket will be directly implemented into a state-of-the-art dust growth and collision model.

Measurement of heat transfer effectiveness during collision of a Leidenfrost droplet with a heated wall - 15447

International Nuclear Information System (INIS)

Park, J.S.; Kim, H.; Bae, S.W.; Kim, K.D.

2015-01-01

resulted in a significant reduction in the total heat transfer amount, likely as the vertical velocity component of the collision is too small to spread out the colliding droplet on the wall. Consequently, both the collision area and resident time are seriously reduced, resulting in the small total heat transfer. (authors)

Multifragmentation in peripheral nucleus-nucleus collisions

International Nuclear Information System (INIS)

Trautmann, W.; Adloff, J.C.; Bouissou, P.; Hubele, J.; Imme, G.; Iori, I.; Kreutz, P.; Leray, S.; Lindenstruth, V.; Liu, Z.; Lynen, U.; Meijer, R.J.; Milkau, U.; Moroni, A.; Mueller, W.F.J.; Ngo, C.; Ogilvie, C.A.; Pochodzalla, J.; Raciti, G.; Rudolf, G.; Schuettauf, A.; Stuttge, L.

1993-10-01

The complete fragmentation of highly excited nuclear systems into fragments of intermediate mass is observed in heavy-ion reactions at relativistic bombarding energies in the range of several hundreds of MeV per nucleon. Similar features are found for peripheral collisions between heavy nuclei and for more central collisions between a heavy and a light nucleus. The partition space explored in multifragment decays is well described by the statistical multifragmentation models. The expansion before breakup is confirmed by the analysis of the measured fragment energies of ternary events in their own rest frame. Collective radial flow is confined to rather small values in these peripheral-type reactions. Many conceptually different models seem to be capable of reproducing the charge correlations measured for the multifragment decays. (orig.)

Advances in ultracold collisions: Experimentation and theory

International Nuclear Information System (INIS)

Weiner, J.

1995-01-01

Collisions between optically cooled and trapped atoms have been the subject of intensive investigation since early proposals discussed their novel features and key importance to the achievement of a gaseous ensemble in a single quantum state. Progress in both experimentation and theory has accelerated rapidly over the last three years, and two reviews, one emphasizing theory and the other, experiments, recount the state of the art published up to about the midpoint of 1993. The purpose of this chapter is to update continuing lines of research set forth in these and earlier works and to relate new results, establishing novel directions for investigation that have appeared in the literature. Two principal questions motivate research into the nature of ultracold collisions: (1) what new phenomena arise when collisionally interacting particles also exchange photons with modes of the radiation field and (2) what are the important two-body collisional heating mechanisms and how can they be overcome in order to achieve the temperature and density conditions appropriate for Bose-Einstein condensation (BEC)? In fact these two questions are not mutually exclusive, and one of the most notable developments in the past year, relevant to both, has been the demonstration of optical control of two-body ultracold collisional processes. Other important issues touching, on one or both of these questions are the magnitude and sign of the scattering length in s-wave collisions between species in various well-defined quantum states, progress in high-resolution trap loss and photoassociation spectroscopy, and application of optical cooling and compression to atomic beams. 58 refs., 21 figs

3D high-resolution radar imaging of small body interiors

Science.gov (United States)

Sava, Paul; Asphaug, Erik

2017-10-01

Answering fundamental questions about the origin and evolution of small planetary bodies hinges on our ability to image their interior structure in detail and at high resolution (Asphaug, 2009). We often infer internal structure from surface observations, e.g. that comet 67P/Churyumov-Gerasimenko is a primordial agglomeration of cometesimals (Massironi et al., 2015). However, the interior structure is not easily accessible without systematic imaging using, e.g., radar transmission and reflection data, as suggested by the CONSERT experiment on Rosetta. Interior imaging depends on observations from multiple viewpoints, as in medical tomography.We discuss radar imaging using methodology adapted from terrestrial exploration seismology (Sava et al., 2015). We primarily focus on full wavefield methods that facilitate high quality imaging of small body interiors characterized by complex structure and large contrasts of physical properties. We consider the case of a monostatic system (co-located transmitters and receivers) operated at two frequency bands, centered around 5 and 15 MHz, from a spacecraft in slow polar orbit around a spinning comet nucleus. Assuming that the spin period is significantly (e.g. 5x) faster than the orbital period, this configuration allows repeated views from multiple directions (Safaeinili et al., 2002)Using realistic numerical experiments, we argue that (1) the comet/asteroid imaging problem is intrinsically 3D and conventional SAR methodology does not satisfy imaging, sampling and resolution requirements; (2) imaging at different frequency bands can provide information about internal surfaces (through migration) and internal volumes (through tomography); (3) interior imaging can be accomplished progressively as data are being acquired through successive orbits around the studied object; (4) imaging resolution can go beyond the apparent radar frequency band by deconvolution of the point-spread-function characterizing the imaging system; and (5

Investigation of Phase Transition-Based Tethered Systems for Small Body Sample Capture

Science.gov (United States)

Quadrelli, Marco; Backes, Paul; Wilkie, Keats; Giersch, Lou; Quijano, Ubaldo; Scharf, Daniel; Mukherjee, Rudranarayan

2009-01-01

This paper summarizes the modeling, simulation, and testing work related to the development of technology to investigate the potential that shape memory actuation has to provide mechanically simple and affordable solutions for delivering assets to a surface and for sample capture and possible return to Earth. We investigate the structural dynamics and controllability aspects of an adaptive beam carrying an end-effector which, by changing equilibrium phases is able to actively decouple the end-effector dynamics from the spacecraft dynamics during the surface contact phase. Asset delivery and sample capture and return are at the heart of several emerging potential missions to small bodies, such as asteroids and comets, and to the surface of large bodies, such as Titan.

Three-dimensional body-wave model of Nepal using finite difference tomography

Science.gov (United States)

Ho, T. M.; Priestley, K.; Roecker, S. W.

2017-12-01

The processes occurring during continent-continent collision are still poorly understood. Ascertaining the seismic properties of the crust and uppermost mantle in such settings provides insight into continental rheology and geodynamics. The most active present-day continent-continent collision is that of India with Eurasia which has created the Himalayas and the Tibetan Plateau. Nepal provides an ideal laboratory for imaging the crustal processes resulting from the Indo-Eurasia collision. We build body wave models using local body wave arrivals picked at stations in Nepal deployed by the Department of Mining and Geology of Nepal. We use the tomographic inversion method of Roecker et al. [2006], the key feature of which is that the travel times are generated using a finite difference solution to the eikonal equation. The advantage of this technique is increased accuracy in the highly heterogeneous medium expected for the Himalayas. Travel times are calculated on a 3D Cartesian grid with a grid spacing of 6 km and intragrid times are estimated by trilinear interpolation. The gridded area spans a region of 80-90o longitude and 25-30o latitude. For a starting velocity model, we use IASP91. Inversion is performed using the LSQR algorithm. Since the damping parameter can have a significant effect on the final solution, we tested a range of damping parameters to fully explore its effect. Much of the seismicity is clustered to the West of Kathmandu at depths Small areas of strong fast wavespeeds exist in the centre of the region in the upper 30 km of the crust. At depths of 40-50 km, large areas of slow wavespeeds are present which track along the plate boundary.

Small body size and extreme cortical bone remodeling indicate phyletic dwarfism in Magyarosaurus dacus (Sauropoda: Titanosauria).

Science.gov (United States)

Stein, Koen; Csiki, Zoltan; Rogers, Kristina Curry; Weishampel, David B; Redelstorff, Ragna; Carballido, Jose L; Sander, P Martin

2010-05-18

Sauropods were the largest terrestrial tetrapods (>10(5) kg) in Earth's history and grew at rates that rival those of extant mammals. Magyarosaurus dacus, a titanosaurian sauropod from the Upper Cretaceous (Maastrichtian) of Romania, is known exclusively from small individuals (dwarfism (phyletic nanism) in dinosaurs, but a recent study suggested that the small Romanian titanosaurs actually represent juveniles of a larger-bodied taxon. Here we present strong histological evidence that M. dacus was indeed a dwarf (phyletic nanoid). Bone histological analysis of an ontogenetic series of Magyarosaurus limb bones indicates that even the smallest Magyarosaurus specimens exhibit a bone microstructure identical to fully mature or old individuals of other sauropod taxa. Comparison of histologies with large-bodied sauropods suggests that Magyarosaurus had an extremely reduced growth rate, but had retained high basal metabolic rates typical for sauropods. The uniquely decreased growth rate and diminutive body size in Magyarosaurus were adaptations to life on a Cretaceous island and show that sauropod dinosaurs were not exempt from general ecological principles limiting body size.

InChIKey collision resistance: an experimental testing

Directory of Open Access Journals (Sweden)

Pletnev Igor

2012-12-01

Full Text Available Abstract InChIKey is a 27-character compacted (hashed version of InChI which is intended for Internet and database searching/indexing and is based on an SHA-256 hash of the InChI character string. The first block of InChIKey encodes molecular skeleton while the second block represents various kinds of isomerism (stereo, tautomeric, etc.. InChIKey is designed to be a nearly unique substitute for the parent InChI. However, a single InChIKey may occasionally map to two or more InChI strings (collision. The appearance of collision itself does not compromise the signature as collision-free hashing is impossible; the only viable approach is to set and keep a reasonable level of collision resistance which is sufficient for typical applications. We tested, in computational experiments, how well the real-life InChIKey collision resistance corresponds to the theoretical estimates expected by design. For this purpose, we analyzed the statistical characteristics of InChIKey for datasets of variable size in comparison to the theoretical statistical frequencies. For the relatively short second block, an exhaustive direct testing was performed. We computed and compared to theory the numbers of collisions for the stereoisomers of Spongistatin I (using the whole set of 67,108,864 isomers and its subsets. For the longer first block, we generated, using custom-made software, InChIKeys for more than 3 × 1010 chemical structures. The statistical behavior of this block was tested by comparison of experimental and theoretical frequencies for the various four-letter sequences which may appear in the first block body. From the results of our computational experiments we conclude that the observed characteristics of InChIKey collision resistance are in good agreement with theoretical expectations.

Research on The Construction of Flexible Multi-body Dynamics Model based on Virtual Components

Science.gov (United States)

Dong, Z. H.; Ye, X.; Yang, F.

2018-05-01

Focus on the harsh operation condition of space manipulator, which cannot afford relative large collision momentum, this paper proposes a new concept and technology, called soft-contact technology. In order to solve the problem of collision dynamics of flexible multi-body system caused by this technology, this paper also proposes the concepts of virtual components and virtual hinges, and constructs flexible dynamic model based on virtual components, and also studies on its solutions. On this basis, this paper uses NX to carry out model and comparison simulation for space manipulator in 3 different modes. The results show that using the model of multi-rigid body + flexible body hinge + controllable damping can make effective control on amplitude for the force and torque caused by target satellite collision.

Hard photons and mesons as probes of heavy ion collision dynamics

International Nuclear Information System (INIS)

Metag, V.

1991-01-01

Hard photon production in heavy ion collisions has been studied by a large number of groups at various laboratory and a large body of data has been collected. Recent results reviewed are summarized here in a systematics for photon emission. A brief discussion of π 0 -production in heavy ion collisions will be given including first results with the Two Arm Photon spectrometer TAPS obtained at SIS. Furthermore, the new perspectives for the study of compressed nuclear matter by meson emission will be outlined. (orig.)

A numerical 4D Collision Risk Model

Science.gov (United States)

Schmitt, Pal; Culloch, Ross; Lieber, Lilian; Kregting, Louise

2017-04-01

With the growing number of marine renewable energy (MRE) devices being installed across the world, some concern has been raised about the possibility of harming mobile, marine fauna by collision. Although physical contact between a MRE device and an organism has not been reported to date, these novel sub-sea structures pose a challenge for accurately estimating collision risks as part of environmental impact assessments. Even if the animal motion is simplified to linear translation, ignoring likely evasive behaviour, the mathematical problem of establishing an impact probability is not trivial. We present a numerical algorithm to obtain such probability distributions using transient, four-dimensional simulations of a novel marine renewable device concept, Deep Green, Minesto's power plant and hereafter referred to as the 'kite' that flies in a figure-of-eight configuration. Simulations were carried out altering several configurations including kite depth, kite speed and kite trajectory while keeping the speed of the moving object constant. Since the kite assembly is defined as two parts in the model, a tether (attached to the seabed) and the kite, collision risk of each part is reported independently. By comparing the number of collisions with the number of collision-free simulations, a probability of impact for each simulated position in the cross- section of the area is considered. Results suggest that close to the bottom, where the tether amplitude is small, the path is always blocked and the impact probability is 100% as expected. However, higher up in the water column, the collision probability is twice as high in the mid line, where the tether passes twice per period than at the extremes of its trajectory. The collision probability distribution is much more complex in the upper end of the water column, where the kite and tether can simultaneously collide with the object. Results demonstrate the viability of such models, which can also incorporate empirical

Retained foreign body following pleural drainage with a small-bore catheter.

Science.gov (United States)

Paddle, Alenka; Elahi, Maqsood; Newcomb, Andrew

2010-01-01

Small-bore radiopaque drains can be used to drain pleural effusions. They offer reliable drainage of simple pleural effusions and provide a safe, less-invasive, more comfortable alternative to the standard tube thoracostomy. Importantly, removal of such drains does not require purse-string sutures and hence can be removed without assistance. We report here the cautionary tale of a retained foreign body related to drainage of a pleural effusion with a Pleurocath in a patient following cardiac surgery to raise awareness of this potential complication. Emphasized is the need for all staff to be familiar with the normal appearance of equipment being utilized in the ward and to report when incomplete removal of drain equipment is suspected. In addition, amendments to insertion techniques for such small-bore drains are proposed to avoid similar undue complications.

SU-F-BRB-05: Collision Avoidance Mapping Using Consumer 3D Camera

Energy Technology Data Exchange (ETDEWEB)

Cardan, R; Popple, R [Univ Alabama Birmingham, Birmingham, AL (United States)

2015-06-15

Purpose: To develop a fast and economical method of scanning a patient’s full body contour for use in collision avoidance mapping without the use of ionizing radiation. Methods: Two consumer level 3D cameras used in electronic gaming were placed in a CT simulator room to scan a phantom patient set up in a high collision probability position. A registration pattern and computer vision algorithms were used to transform the scan into the appropriate coordinate systems. The cameras were then used to scan the surface of a gantry in the treatment vault. Each scan was converted into a polygon mesh for collision testing in a general purpose polygon interference algorithm. All clinically relevant transforms were applied to the gantry and patient support to create a map of all possible collisions. The map was then tested for accuracy by physically testing the collisions with the phantom in the vault. Results: The scanning fidelity of both the gantry and patient was sufficient to produce a collision prediction accuracy of 97.1% with 64620 geometry states tested in 11.5 s. The total scanning time including computation, transformation, and generation was 22.3 seconds. Conclusion: Our results demonstrate an economical system to generate collision avoidance maps. Future work includes testing the speed of the framework in real-time collision avoidance scenarios. Research partially supported by a grant from Varian Medical Systems.

Effect of three-body forces on the phase behavior of charged colloids

International Nuclear Information System (INIS)

Wu, J. Z.; Bratko, D.; Blanch, H. W.; Prausnitz, J. M.

2000-01-01

Statistical-thermodynamic theory for predicting the phase behavior of a colloidal solution requires the pair interaction potential between colloidal particles in solution. In practice, it is necessary to assume pairwise additivity for the potential of mean force between colloidal particles, but little is known concerning the validity of this assumption. This paper concerns interaction between small charged colloids, such as surfactant micelles or globular proteins, in electrolyte solutions and the multibody effect on phase behavior. Monte Carlo simulations for isolated colloidal triplets in equilateral configurations show that, while the three-body force is repulsive when the three particles are near contact, it becomes short-ranged attractive at further separations, contrary to a previous study where the triplet force is attractive at all separations. The three-body force arises mainly from hard-sphere collisions between colloids and small ions; it is most significant in solutions of monovalent salt at low concentration where charged colloids experience strong electrostatic interactions. To illustrate the effect of three-body forces on the phase behavior of charged colloids, we calculated the densities of coexisting phases using van der Waals-type theories for colloidal solutions and for crystals. For the conditions investigated in this work, even though the magnitude of the three-body force may be as large as 10% of the total force at small separations, three-body forces do not have a major effect on the densities of binary coexisting phases. However, coexisting densities calculated using Derjaguin-Landau-Verwey-Overbeek theory are much different from those calculated using our simulated potential of mean force. (c) 2000 American Institute of Physics

Discovery of hydrodynamic behavior in high energy heavy ion collisions

International Nuclear Information System (INIS)

Hamagaki, Hideki

2010-01-01

The objective of high energy heavy ion collision experiments is creating high temperature and high density states to investigate hadron matter properties in such extreme conditions. Since the start of heavy ion collision experiments with BEVALAC, knowledge of the space-time evolution of collision has become indispensable for understanding the hadronic matter properties. This problem is reviewed here from the hydrodynamics view point. Although its importance has been generally recognized since the time of BEVALAC, the hydrodynamic description has not been successful because the hydrodynamic model assuming non-viscous or small fluid had not been considered to be enough to properly describe the space-time evolution of hadron-hadron collisions until the RHIC experiments. Items of the following titles are picked up and reviewed here: Development of heavy ion accelerations; Space-time evolution of hadron collision process and hydrodynamic model; Chemical freezing and kinematical freezing, including transverse momentum spectra at proton-proton collisions and particle spectra in heavy ion collisions; Elliptical azimuthal angle anisotropy; Discovery of hydrodynamic flow at BEVALAC; Problems of incident beam dependence of v2; Elliptic azimuthal angle anisotropy at RHIC; What is it that carries the elliptic anisotropy? Discussion of attainment of thermodynamical equilibrium state at RHIC; and finally investigations of fluid properties other than azimuthal anisotropy, such as, Fluid properties probed by heavy quarks and Observing QCD fluid responses. (S. Funahashi)

Interface-Resolving Simulation of Collision Efficiency of Cloud Droplets

Science.gov (United States)

Wang, Lian-Ping; Peng, Cheng; Rosa, Bodgan; Onishi, Ryo

2017-11-01

Small-scale air turbulence could enhance the geometric collision rate of cloud droplets while large-scale air turbulence could augment the diffusional growth of cloud droplets. Air turbulence could also enhance the collision efficiency of cloud droplets. Accurate simulation of collision efficiency, however, requires capture of the multi-scale droplet-turbulence and droplet-droplet interactions, which has only been partially achieved in the recent past using the hybrid direct numerical simulation (HDNS) approach. % where Stokes disturbance flow is assumed. The HDNS approach has two major drawbacks: (1) the short-range droplet-droplet interaction is not treated rigorously; (2) the finite-Reynolds number correction to the collision efficiency is not included. In this talk, using two independent numerical methods, we will develop an interface-resolved simulation approach in which the disturbance flows are directly resolved numerically, combined with a rigorous lubrication correction model for near-field droplet-droplet interaction. This multi-scale approach is first used to study the effect of finite flow Reynolds numbers on the droplet collision efficiency in still air. Our simulation results show a significant finite-Re effect on collision efficiency when the droplets are of similar sizes. Preliminary results on integrating this approach in a turbulent flow laden with droplets will also be presented. This work is partially supported by the National Science Foundation.

Summary of Reported Whale-Vessel Collisions in Alaskan Waters

Directory of Open Access Journals (Sweden)

Janet L. Neilson

2012-01-01

Full Text Available Here we summarize 108 reported whale-vessel collisions in Alaska from 1978–2011, of which 25 are known to have resulted in the whale's death. We found 89 definite and 19 possible/probable strikes based on standard criteria we created for this study. Most strikes involved humpback whales (86% with six other species documented. Small vessel strikes were most common (<15 m, 60%, but medium (15–79 m, 27% and large (≥80 m, 13% vessels also struck whales. Among the 25 mortalities, vessel length was known in seven cases (190–294 m and vessel speed was known in three cases (12–19 kn. In 36 cases, human injury or property damage resulted from the collision, and at least 15 people were thrown into the water. In 15 cases humpback whales struck anchored or drifting vessels, suggesting the whales did not detect the vessels. Documenting collisions in Alaska will remain challenging due to remoteness and resource limitations. For a better understanding of the factors contributing to lethal collisions, we recommend (1 systematic documentation of collisions, including vessel size and speed; (2 greater efforts to necropsy stranded whales; (3 using experienced teams focused on determining cause of death; (4 using standard criteria for validating collision reports, such as those presented in this paper.

Three-dimensional imaging of atomic four-body processes

CERN Document Server

Schulz, M; Fischer, D; Kollmus, H; Madison, D H; Jones, S; Ullrich, J

2003-01-01

To understand the physical processes that occur in nature we need to obtain a solid concept about the 'fundamental' forces acting between pairs of elementary particles. it is also necessary to describe the temporal and spatial evolution of many mutually interacting particles under the influence of these forces. This latter step, known as the few-body problem, remains an important unsolved problem in physics. Experiments involving atomic collisions represent a useful testing ground for studying the few-body problem. For the single ionization of a helium atom by charged particle impact, kinematically complete experiments have been performed since 1969. The theoretical analysis of such experiments was thought to yield a complete picture of the basic features of the collision process, at least for large collision energies. These conclusions are, however, almost exclusively based on studies of restricted electron-emission geometries. We report three- dimensional images of the complete electron emission pattern for...

Dry coupling for whole-body small-animal photoacoustic computed tomography

Science.gov (United States)

Yeh, Chenghung; Li, Lei; Zhu, Liren; Xia, Jun; Li, Chiye; Chen, Wanyi; Garcia-Uribe, Alejandro; Maslov, Konstantin I.; Wang, Lihong V.

2017-04-01

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using a whole-body small-animal ring-shaped photoacoustic computed tomography system. Dry coupling was found to provide image quality comparable to that of conventional water coupling.

Memory effects in dissipative nucleus-nucleus collision

CERN Document Server

Yadav, H L

2002-01-01

A macroscopic dynamical model within the framework of a multidimensional Fokker-Planck equation is employed for a theoretical description of low-energy dissipative collisions between two heavy nuclei. The effect of two-body collisions leading to intrinsic equilibrium has been treated phenomenologically using the basic concepts of dissipative diabatic dynamics. The heavy-ion reaction sup 8 sup 6 Kr(8.18 MeV/u) + sup 1 sup 6 sup 6 Er has been as a prototype to study and demonstrate the memory effects for dissipation and diffusion processes. Our calculated results for the deflection angle, angular distributions d sigma/d theta sub c sub m , energy distributions d sigma/d DELTA EPSILON, and element distributions d sigma/d ZETA illustrate a remarkable dependence on the memory effects and are consistent with the experimental data

Partial body irradiation of small laboratory animals with an industrial X-ray tube

International Nuclear Information System (INIS)

Frenzel, Thorsten; Kruell, Andreas; Grohmann, Carsten; Schumacher, Udo

2014-01-01

Dedicated precise small laboratory animal irradiation sources are needed for basic cancer research and to meet this need expensive high precision radiation devices have been developed. To avoid such expenses a cost efficient way is presented to construct a device for partial body irradiation of small laboratory animals by adding specific components to an industrial X-ray tube. A custom made radiation field tube was added to an industrial 200 kV X-ray tube. A light field display as well as a monitor ionization chamber were implemented. The field size can rapidly be changed by individual inserts of MCP96 that are used for secondary collimation of the beam. Depth dose curves and cross sectional profiles were determined with the use of a custom made water phantom. More components like positioning lasers, a custom made treatment couch, and a commercial isoflurane anesthesia unit were added to complete the system. With the accessories described secondary small field sizes down to 10 by 10 mm 2 (secondary collimator size) could be achieved. The dosimetry of the beam was constructed like those for conventional stereotactical clinical linear accelerators. The water phantom created showed an accuracy of 1 mm and was well suited for all measurements. With the anesthesia unit attached to the custom made treatment couch the system is ideal for the radiation treatment of small laboratory animals like mice. It was feasible to shrink the field size of an industrial X-ray tube from whole animal irradiation to precise partial body irradiation of small laboratory animals. Even smaller secondary collimator sizes than 10 by 10 mm 2 are feasible with adequate secondary collimator inserts. Our custom made water phantom was well suited for the basic dosimetry of the X-ray tube.

Charmed hadron production in pp collision

Science.gov (United States)

Goswami, Umananda Dev

2007-10-01

We investigated the production of charmed hadrons ( D+, D-, D0, D, Λc+, Λ¯c-) in pp collisions as a function of √{s}, xF, p⊥2 and p⊥ in the framework of the QGSJET model. The study of charmed hadron production characteristics in pp collision is particularly important for cosmic ray physics in the context of atmospheric prompt lepton fluxes. Here our aim is to check the reliability of the QGSJET model to be used to study the production of charmed hadrons in cosmic ray hadronic interactions with air nuclei. Charmed hadroproduction cross sections or the charmed hadron average multiplicities in pp collisions are relatively very small. The maximum production of all charmed hadrons takes place with low values of xF, p⊥2, and p⊥ within a small range for all values of √{s} under study. Charmed hadroproduction cross sections as a function of xF and p⊥2 are compared with the LEBC-EHS and LEBC-MPS experiment data for D-meson production. The agreement is quite satisfactory for smaller values of p⊥2 (⩽2 (GeV/c) 2). There is an asymmetry in charmed hadroproduction in pp collision. For all xF, asymmetry is prominent in the low value of √{s}. There is a strong preference for producing Λc+ rather than Λ¯c-baryons, while that for producing D¯ rather than D-mesons for this range of √{s}. Asymmetry increases from zero to ±1 around xF = 0.3 for all values of √{s} and for all charmed hardron groups. The patterns of asymmetric production of different charmed hadrons with xF are approximately the same as that with √{s}. We compare our calculation with the data from Fermilab experiment E781 (SELEX) for Λc-baryon production. The agreement is quite good. The asymmetry of charmed hadroproduction with p⊥ does not follow any well defined pattern.

The effect of feeding position and body size on the capacity of small ...

African Journals Online (AJOL)

The effect of feeding position and body size on the capacity of small ruminants to reach, for food when fed through barriers. ... The barrier allowed the neck to pass through, but not the shoulders. It was hypothesized that goats would have larger reach than sheep and that for each species, horizontal reach forwards, F, ...

What can nuclear collisions teach us about the boiling of water or the formation of multi-star systems

Science.gov (United States)

Gross, D. H. E.

2001-11-01

Phase transitions in nuclei, small atomic clusters and self-gravitating systems demand the extension of thermo-statistics to "Small" systems. The main obstacle is the thermodynamic limit. It is shown how the original definition of the entropy by Boltzmann as the volume of the energy-manifold of the N-body phase space allows a geometrical definition of the entropy as function of the conserved quantities. Without invoking the thermodynamic limit the whole "zoo" of phase transitions and critical points/lines can be unambiguously defined. The relation to the Yang-Lee singularities of the grand-canonical partition sum is pointed out. It is shown that just phase transitions in non-extensive systems give the complete set of characteristic parameters of the transition including the surface tension. Nuclear heavy-ion collisions are an experimental playground to explore this extension of thermo-statistics

Development of collision dynamics models to estimate the results of full-scale rail vehicle impact tests : Tufts University Master's Thesis

Science.gov (United States)

2000-11-01

In an effort to study occupant survivability in train collisions, analyses and tests were conducted to understand and improve the crashworthiness of rail vehicles. A collision dynamics model was developed in order to estimate the rigid body motion of...

A unique tripartite collision tumor of the esophagus

Science.gov (United States)

Schizas, Dimitrios; Michalinos, Adamantios; Alexandrou, Paraskevi; Moris, Demetrios; Baliou, Evangelia; Tsilimigras, Diamantis; Throupis, Theodore; Liakakos, Theodore

2017-01-01

Abstract Rationale: We report a unique case of a tripartite esophageal collision tumor consisting of three separate histologic types. Patients concerns: Therapeutic dilemmas on the proper treatment of those rare neoplasms remain unanswered considering both proper surgical therapy and adjuvant therapy. Diagnose: In this paper, we report a unique case of a patient with a tripartite esophageal collision tumor consisting of a small cell carcinoma, an adenocarcinoma of medium differentiation and a signet ring cell carcinoma. Diagnosis is difficult as clinical presentation of the patient was undistinguishable from other, commoner tumor types. Interventions: The patient's diagnostic and therapeutic course along with available data on the collisions tumor's biological behavior and treatment are briefly discussed. Outcomes: Esophagectomy is the best treatment options for these patients. Unique nature of this tumor demands aggresive oncologic treatment. Lessons: Collision tumors are rare neoplasms consisting of distinct cell populations developing in juxtaposition to one another without any areas of intermingling. Various cell types can be found. However, collision neoplasms of the esophagus combining adenomatous and neuroendocrine components are exceedingly rare, with only 5 cases described to date in the literature. Given their rarity, limited information is available on their tumorigenesis, biological behavior and clinical course. In general, these tumors are aggressive neoplasms and significantly affect patient treatment and prognosis. PMID:29245236

Electron-molecule collisions

International Nuclear Information System (INIS)

Shimamura, I.; Takayanagi, K.

1984-01-01

The study of collision processes plays an important research role in modern physics. Many significant discoveries have been made by means of collision experiments. Based on theoretical, experimental, and computational studies, this volume presents an overview detailing the basic processes of electron-molecule collisions. The editors have collected papers-written by a group of international experts-that consider a diverse range of phenomena occurring in electronmolecule collisions. The volume discusses first the basic formulation for scattering problems and then gives an outline of the physics of electron-molecule collisions. The main topics covered are rotational transitions, vibrational transitions, dissociation of molecules in slow collisions, the electron-molecule collision as a spectroscopic tool for studying molecular electronic structures, and experimental and computational techniques for determining the cross sections. These well-referenced chapters are self-contained and can be read independently or consecutively. Authoritative and up-to-date, Electron-Molecule Collisions is a useful addition to the libraries of students and researchers in the fields of atomic, molecular, and chemical physics, and physical chemistry

Collision Based Blood Cell Distribution of the Blood Flow

Science.gov (United States)

Cinar, Yildirim

2003-11-01

Introduction: The goal of the study is the determination of the energy transferring process between colliding masses and the application of the results to the distribution of the cell, velocity and kinetic energy in arterial blood flow. Methods: Mathematical methods and models were used to explain the collision between two moving systems, and the distribution of linear momentum, rectilinear velocity, and kinetic energy in a collision. Results: According to decrease of mass of the second system, the velocity and momentum of constant mass of the first system are decreased, and linearly decreasing mass of the second system captures a larger amount of the kinetic energy and the rectilinear velocity of the collision system on a logarithmic scale. Discussion: The cause of concentration of blood cells at the center of blood flow an artery is not explained by Bernoulli principle alone but the kinetic energy and velocity distribution due to collision between the big mass of the arterial wall and the small mass of blood cells must be considered as well.

Dynamics of the single and double ionization of helium in fast proton collisions

International Nuclear Information System (INIS)

Doerner, R.; Schmidt-Boecking, H.

1991-08-01

A new experimental approach, designed to measure differential ionisation and electron capture cross sections for relativistic heavy ion beams, has been developed and was used to investigate dynamic mechanisms of Helium single and double ionisation in collisions with fast protons. Detailed insight into the dynamics of the ionisation process has been obtained. The experimental results prove, that the many-body momentum exchange between all particles involved, the projectile and target nucleus as well as the emitted electrons, has to be incorporated in order to correctly describe the ionisation collision dynamics. For the proton on Helium collision system the transverse momenta of projectile and recoil-ion were found to be of comparable magnitude only for very close collisions and large scattering angles above 1 mrad, which contribute less than 3% to the total ionisation cross section. (orig./HSI) [de

Systematics in Rydberg state excitations for ion-atom collisions

International Nuclear Information System (INIS)

Andresen, B.; Jensen, K.; Petersen, N.B.; Veje, E.

1976-01-01

Rydberg state excitations in the Ne + , Mg + -He collisions have been studied in the projectile energy range 10-75 keV by means of optical spectrometry in a search for systematic trends. The relative excitation cross sections for levels of a Rydberg term series are found to follow a general (nsup(x))sup(P) behaviour with P < approximately -3 varying with collision energy and particles, regardless of whether the excited state population results from direct excitation, single electron transfer, or double electron transfer. At higher collision energies P is approximately -3 as predicted by theory. Polarization of the emitted line radiation indicates that there is no general rule for the relative excitation of the different magnetic substates of the same level. A statistical distribution of excitation is found for levels within the same term when the fine structure splitting is small. (Auth.)

Small-animal whole-body imaging using a photoacoustic full ring array system

Science.gov (United States)

Xia, Jun; Guo, Zijian; Aguirre, Andres; Zhu, Quing; Wang, Lihong V.

2011-03-01

In this report, we present a novel 3D photoacoustic computed tomography (PACT) system for small-animal whole-body imaging. The PACT system, based on a 512-element full-ring transducer array, received photoacoustic signals primarily from a 2-mm-thick slice. The light was generated by a pulse laser, and can either illuminate from the top or be reshaped to illuminate the sample from the side, using a conical lens and an optical condenser. The PACT system was capable of acquiring an in-plane image in 1.6 s; by scanning the sample in the elevational direction, a 3D tomographic image could be constructed. We tested the system by imaging a cylindrical phantom made of human hairs immersed in a scattering medium. The reconstructed image achieved an in-plane resolution of 0.1 mm and an elevational resolution of 1 mm. After deconvolution in the elevational direction, the 3D image was found to match well with the phantom. The system was also used to image a baby mouse in situ; the spinal cord and ribs can be seen easily in the reconstructed image. Our results demonstrate that the PACT system has the potential to be used for fast small-animal whole-body tomographic imaging.

Resonance production in high energy collisions from small to big systems

Science.gov (United States)

Werner, K.; Knospe, A. G.; Markert, C.; Guiot, B.; Karpenko, Iu.; Pierog, T.; Sophys, G.; Stefaniak, M.; Bleicher, M.; Steinheimer, J.

2018-02-01

The aim of this paper is to understand resonance production (and more generally particle production) for different collision systems, namely proton-proton (pp), proton-nucleus (pA), and nucleus-nucleus (AA) scattering at the LHC. We will investigate in particular particle yields and ratios versus multiplicity, using the same multiplicity definition for the three different systems, in order to analyse in a compact way the evolution of particle production with the system size and the origin of a very different system size dependence of the different particles.

WT Bird. Bird collision recording for offshore wind farms

Energy Technology Data Exchange (ETDEWEB)

Wiggelinkhuizen, E.J.; Rademakers, L.W.M.M.; Barhorst, S.A.M. [ECN Wind Energy, Petten (Netherlands); Den Boon, H. [E-Connection Project, Bunnik (Netherlands); Dirksen, S. [Bureau Waardenburg, Culemborg (Netherlands); Schekkerman, H. [Alterra, Wageningen (Netherlands)

2004-11-01

A new method for monitoring of bird collisions has been developed using video and audio registrations that are triggered by sound and vibration measurements. Remote access to the recorded images and sounds makes it possible to count the number of collisions as well as to identify the species. After the successful proof of principle and evaluation on small land-based turbines the system is now being designed for offshore wind farms. Currently the triggering system and video and audio registration are being tested on large land-based wind turbines using bird dummies. Tests of three complete prototype systems are planned for 2005.

Non unitarity effects in the time evolution of one body observables

International Nuclear Information System (INIS)

Nemes, M.C.; Toledo Piza, A.F.R. de

1982-01-01

We present a formal derivation of the exact dynamics of the one body density matrix. Its essential ingredients are shown to be: a) a mean field unitary time evolution, b) irreducible non unitary corrections to it (collision effects) and c) the time evolution of initial state correlations (which contributes to both a) and b). The qualitative importance of collision effects to the expectation value of one body operators is discussed and a quantitative study is carried out within the framework of an exactly soluble model, the non unitary contributions vary from 10% to over 100%

PREDICTIVE POTENTIAL FIELD-BASED COLLISION AVOIDANCE FOR MULTICOPTERS

Directory of Open Access Journals (Sweden)

M. Nieuwenhuisen

2013-08-01

Full Text Available Reliable obstacle avoidance is a key to navigating with UAVs in the close vicinity of static and dynamic obstacles. Wheel-based mobile robots are often equipped with 2D or 3D laser range finders that cover the 2D workspace sufficiently accurate and at a high rate. Micro UAV platforms operate in a 3D environment, but the restricted payload prohibits the use of fast state-of-the-art 3D sensors. Thus, perception of small obstacles is often only possible in the vicinity of the UAV and a fast collision avoidance system is necessary. We propose a reactive collision avoidance system based on artificial potential fields, that takes the special dynamics of UAVs into account by predicting the influence of obstacles on the estimated trajectory in the near future using a learned motion model. Experimental evaluation shows that the prediction leads to smoother trajectories and allows to navigate collision-free through passageways.

Nucleus-Nucleus Collision as Superposition of Nucleon-Nucleus Collisions

International Nuclear Information System (INIS)

Orlova, G.I.; Adamovich, M.I.; Aggarwal, M.M.; Alexandrov, Y.A.; Andreeva, N.P.; Badyal, S.K.; Basova, E.S.; Bhalla, K.B.; Bhasin, A.; Bhatia, V.S.; Bradnova, V.; Bubnov, V.I.; Cai, X.; Chasnikov, I.Y.; Chen, G.M.; Chernova, L.P.; Chernyavsky, M.M.; Dhamija, S.; Chenawi, K.El; Felea, D.; Feng, S.Q.; Gaitinov, A.S.; Ganssauge, E.R.; Garpman, S.; Gerassimov, S.G.; Gheata, A.; Gheata, M.; Grote, J.; Gulamov, K.G.; Gupta, S.K.; Gupta, V.K.; Henjes, U.; Jakobsson, B.; Kanygina, E.K.; Karabova, M.; Kharlamov, S.P.; Kovalenko, A.D.; Krasnov, S.A.; Kumar, V.; Larionova, V.G.; Li, Y.X.; Liu, L.S.; Lokanathan, S.; Lord, J.J.; Lukicheva, N.S.; Lu, Y.; Luo, S.B.; Mangotra, L.K.; Manhas, I.; Mittra, I.S.; Musaeva, A.K.; Nasyrov, S.Z.; Navotny, V.S.; Nystrand, J.; Otterlund, I.; Peresadko, N.G.; Qian, W.Y.; Qin, Y.M.; Raniwala, R.; Rao, N.K.; Roeper, M.; Rusakova, V.V.; Saidkhanov, N.; Salmanova, N.A.; Seitimbetov, A.M.; Sethi, R.; Singh, B.; Skelding, D.; Soderstrem, K.; Stenlund, E.; Svechnikova, L.N.; Svensson, T.; Tawfik, A.M.; Tothova, M.; Tretyakova, M.I.; Trofimova, T.P.; Tuleeva, U.I.; Vashisht, Vani; Vokal, S.; Vrlakova, J.; Wang, H.Q.; Wang, X.R.; Weng, Z.Q.; Wilkes, R.J.; Yang, C.B.; Yin, Z.B.; Yu, L.Z.; Zhang, D.H.; Zheng, P.Y.; Zhokhova, S.I.; Zhou, D.C.

1999-01-01

Angular distributions of charged particles produced in 16 O and 32 S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b NA , that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus

Nucleus-Nucleus Collision as Superposition of Nucleon-Nucleus Collisions

Energy Technology Data Exchange (ETDEWEB)

Orlova, G I; Adamovich, M I; Aggarwal, M M; Alexandrov, Y A; Andreeva, N P; Badyal, S K; Basova, E S; Bhalla, K B; Bhasin, A; Bhatia, V S; Bradnova, V; Bubnov, V I; Cai, X; Chasnikov, I Y; Chen, G M; Chernova, L P; Chernyavsky, M M; Dhamija, S; Chenawi, K El; Felea, D; Feng, S Q; Gaitinov, A S; Ganssauge, E R; Garpman, S; Gerassimov, S G; Gheata, A; Gheata, M; Grote, J; Gulamov, K G; Gupta, S K; Gupta, V K; Henjes, U; Jakobsson, B; Kanygina, E K; Karabova, M; Kharlamov, S P; Kovalenko, A D; Krasnov, S A; Kumar, V; Larionova, V G; Li, Y X; Liu, L S; Lokanathan, S; Lord, J J; Lukicheva, N S; Lu, Y; Luo, S B; Mangotra, L K; Manhas, I; Mittra, I S; Musaeva, A K; Nasyrov, S Z; Navotny, V S; Nystrand, J; Otterlund, I; Peresadko, N G; Qian, W Y; Qin, Y M; Raniwala, R; Rao, N K; Roeper, M; Rusakova, V V; Saidkhanov, N; Salmanova, N A; Seitimbetov, A M; Sethi, R; Singh, B; Skelding, D; Soderstrem, K; Stenlund, E; Svechnikova, L N; Svensson, T; Tawfik, A M; Tothova, M; Tretyakova, M I; Trofimova, T P; Tuleeva, U I; Vashisht, Vani; Vokal, S; Vrlakova, J; Wang, H Q; Wang, X R; Weng, Z Q; Wilkes, R J; Yang, C B; Yin, Z B; Yu, L Z; Zhang, D H; Zheng, P Y; Zhokhova, S I; Zhou, D C

1999-03-01

Angular distributions of charged particles produced in {sup 16}O and {sup 32}S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b{sub NA}, that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus.

Nucleus-nucleus collision as superposition of nucleon-nucleus collisions

International Nuclear Information System (INIS)

Orlova, G.I.; Adamovich, M.I.; Aggarwal, M.M.

1999-01-01

Angular distributions of charged particles produced in 16 O and 32 S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b NA , that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus. (orig.)

NOTE: Patient-specific planning for prevention of mechanical collisions during radiotherapy

Science.gov (United States)

Nioutsikou, Elena; Bedford, James L.; Webb, Steve

2003-11-01

A common unwanted difficulty in treatment planning, especially in non-coplanar radiotherapy set-ups, is the potential collision of the rotating gantry with the couch and/or the patient's body. A technique and computer program that detects these and signals avoidance of such beam directions is presented. The problem was approached using analytical geometry. The separate components within the treatment room have either been measured and modelled for an Elekta linear accelerator, or read out from a Pinnacle3 treatment planning system and are represented as an integer grid of points in three-dimensional (3D) space. The module is attached to the treatment planning system and can provide rejection or acceptance of unwanted beam directions in a plan. In contrast to previous work that has only used patient models, each individual patient's outlines are considered here in their actual treatment position inclusive of any immobilization device. The extremities of the patient superiorly and inferiorly to the scanned region are simulated by an expanded version of the RANDO phantom. In this way, 'potential' collisions can be detected in addition to the certain ones. Patient position is not a limiting factor for the accuracy of the collision detection anymore, as each set-up is always created around the isocentre. Maps of allowed and forbidden zones within the treatment suite have been created by running the code for all possible gantry and couch angles for three commonly arising cases: a head and neck plan utilizing a small stereotactic collimator, a prostate plan with multileaf collimators and an abdominal plan with the lead tray attached. In the last case, the 3D map permitted significantly fewer set-up combinations. Good agreement between prediction and experiment confirmed the capability of the program and introduces a promising add-on for treatment planning.

Supplementing five-point body condition score with body fat percentage increases the sensitivity for assessing overweight status of small to medium sized dogs

Directory of Open Access Journals (Sweden)

Arai T

2012-09-01

Full Text Available Gebin Li,1 Peter Lee,1 Nobuko Mori,1 Ichiro Yamamoto,1 Koh Kawasumi,1 Hisao Tanabe,2 Toshiro Arai11Department of Veterinary Science, School of Veterinary Medicine, Nippon Veterinary and Life Science University, 2Komazawa Animal Hospital, Tokyo, JapanBackground and methods: Currently, five-point body condition scoring (BCS is widely used by veterinarians and clinicians to assess adiposity in dogs in Japan. However, BCS score assignment is subjective in nature, and most clinicians do not score with half points, instead preferring to round off values, thereby rendering less accurate assessments. Therefore, we sought to determine whether assessing body fat percentage using simple morphometric measurements and supplementing this with five-point BCS can have increased sensitivity for detecting increasing adiposity in overweight small-medium sized dog breeds via plasma metabolite validation.Results: Overall, lean body fat percentage was determined to be 15%–22% for male (non-neutered/neutered dogs and 15%–25% for female (nonspayed/spayed. Dogs categorized as overweight by BCS had significantly higher levels of nonesterified fatty acids (P = 0.005, whereas animals categorized as overweight by BCS + body fat percentage were observed to have significantly higher levels of nonesterified fatty acids (P = 0.006, total cholesterol (P = 0.029, and triglycerides (P = 0.001 than lean animals. The increased sensitivity due to body fat percentage for gauging alterations in plasma metabolite levels may be due to increased correlation strength. Body fat percentage correlated positively with plasma insulin (r = 0.627, P = 0.002, nonesterified fatty acids (r = 0.674, P < 0.001, total cholesterol (r = 0.825, P < 0.0001, triglycerides (r = 0.5823, P < 0.005, blood urea nitrogen (r = 0.429, P < 0.05, creatinine (r = 0.490, P = 0.021, and total protein (r = 0.737, P< 0.0001 levels, which all tend to increase as a result of increasing adiposity

An Optimized Virtual Scheme for Reducing Collisions in MAC Layer

OpenAIRE

M. Sivakumar; S. Saravanan

2015-01-01

The main function of Medium Access Control (MAC) is to share the channel efficiently between all nodes. In the real-time scenario, there will be certain amount of wastage in bandwidth due to back-off periods. More bandwidth will be wasted in idle state if the back-off period is very high and collision may occur if the back-off period is small. So, an optimization is needed for this problem. The main objective of the work is to reduce delay due to back-off period thereby reducing collision and...

Atomic and molecular collision processes

International Nuclear Information System (INIS)

Norcross, D.W.

1991-01-01

530Accomplishments during the course of a 44-month program of code development and high precision calculations for electron collisions with atoms, atomic ions, and molecules are summarized. In electron-atom and -ion collisions, we were primarily concerned with the fundamental physics of the process that controls excitation in high temperature plasmas. In the molecular work, we pursued the development of techniques for accurate calculations of ro-vibrational excitation of polyatomic molecules, to the modeling of gas-phase laser systems. Highlights from the seven technical paper published as a result of this contract include: The resolution of a long history of unexplained anomalies and experimental/theoretical discrepancies by a demonstration that the Coulomb phase must be included in scattering amplitudes for electron-ion collisions. Definitive close-coupling calculations of cross sections for electron impact excitation of Be + , using a very elaborate expansion for the collision system and inclusion of both one- and two-body terms for the effect of core polarization. Detailed state-of-the-art calculations for electron-impact excitation of the sodium-like ion A ell 2+ that included core-polarization interactions, and which also produced new data on bound-state energy levels for the magnesium-like ion A ell + and oscillator strengths for A ell 2+ . Partial cross sections for excitation of the 3p level of sodium at energies just above threshold calculated using a four-state close-coupling approach, including both total cross sections and those for excitation as a function of the change in the spin and orbital angular momentum projection quantum numbers of the target electron. Generalization of our electron-molecule scattering code to carry out full vibrational close-coupling calculations with an exact treatment of exchange and with a parameter-free representation of correlation and polarization interactions, and application to HF and H 2

The Concept of Collision-Free Motion Planning Using a Dynamic Collision Map

Directory of Open Access Journals (Sweden)

Keum-Bae Cho

2014-09-01

Full Text Available In this paper, we address a new method for the collision-free motion planning of a mobile robot in dynamic environments. The motion planner is based on the concept of a conventional collision map (CCM, represented on the L(travel length-T(time plane. We extend the CCM with dynamic information about obstacles, such as linear acceleration and angular velocity, providing useful information for estimating variation in the collision map. We first analyse the effect of the dynamic motion of an obstacle in the collision region. We then define the measure of collision dispersion (MOCD. The dynamic collision map (DCM is generated by drawing the MOCD on the CCM. To evaluate a collision-free motion planner using the DCM, we extend the DCM with MOCD, then draw the unreachable region and deadlocked regions. Finally, we construct a collision-free motion planner using the information from the extended DCM.

Surface Collisions of Small Cluster Ions at Incident Energies 10-102 eV

Czech Academy of Sciences Publication Activity Database

Herman, Zdeněk

2004-01-01

Roč. 233, - (2004), s. 361-371 ISSN 1387-3806 R&D Projects: GA MŠk ME 561 Grant - others:XE(CZ) EURATOM-IPP.CR Institutional research plan: CEZ:AV0Z4040901 Keywords : surface collisions * cluster ions * unimolecular dissociation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.235, year: 2004

Resonance production in high energy collisions from small to big systems

Directory of Open Access Journals (Sweden)

Werner K.

2018-01-01

Full Text Available The aim of this paper is to understand resonance production (and more generally particle production for different collision systems, namely proton-proton (pp, proton-nucleus (pA, and nucleus-nucleus (AA scattering at the LHC. We will investigate in particular particle yields and ratios versus multiplicity, using the same multiplicity definition for the three different systems, in order to analyse in a compact way the evolution of particle production with the system size and the origin of a very different system size dependence of the different particles.

Anaphylaxis Imaging: Non-Invasive Measurement of Surface Body Temperature and Physical Activity in Small Animals.

Directory of Open Access Journals (Sweden)

Krisztina Manzano-Szalai

Full Text Available In highly sensitized patients, the encounter with a specific allergen from food, insect stings or medications may rapidly induce systemic anaphylaxis with potentially lethal symptoms. Countless animal models of anaphylaxis, most often in BALB/c mice, were established to understand the pathophysiology and to prove the safety of different treatments. The most common symptoms during anaphylactic shock are drop of body temperature and reduced physical activity. To refine, improve and objectify the currently applied manual monitoring methods, we developed an imaging method for the automated, non-invasive measurement of the whole-body surface temperature and, at the same time, of the horizontal and vertical movement activity of small animals. We tested the anaphylaxis imaging in three in vivo allergy mouse models for i milk allergy, ii peanut allergy and iii egg allergy. These proof-of-principle experiments suggest that the imaging technology represents a reliable non-invasive method for the objective monitoring of small animals during anaphylaxis over time. We propose that the method will be useful for monitoring diseases associated with both, changes in body temperature and in physical behaviour.

W and Z bosons with CMS in pp, pPb and PbPb collisions

Energy Technology Data Exchange (ETDEWEB)

Chapon, Émilien, E-mail: emilien.chapon@cern.ch

2016-12-15

Electroweak boson production is an important benchmark process in high-energy heavy-ion collisions at the LHC. W and Z bosons do not participate in the strong interaction and their leptonic decays provide medium-blind probes of the initial state of the collisions. The final results on the W and Z production in pPb collisions at 5.02 TeV, combining both the muon and electron channels, will be presented. When compared to theory calculations that include nuclear modifications to the parton distributions, data show a clear sensitivity to this type of effects. The final results in PbPb collisions at 2.76 TeV, compared to pp collisions at the same centre of mass energy, will also be presented. The centrality dependence confirms the binary scaling of hard probes in heavy-ion collisions, while the differential cross sections points to initial state effects small compared to the statistical precision of the available data.

Time-dependent shell-model theory of dissipative heavy-ion collisions

International Nuclear Information System (INIS)

Ayik, S.; Noerenberg, W.

1982-01-01

A transport theory is formulated within a time-dependent shell-model approach. Time averaging of the equations for macroscopic quantities lead to irreversibility and justifies weak-coupling limit and Markov approximation for the (energy-conserving) one- and two-body collision terms. Two coupled equations for the occupation probabilities of dynamical single-particle states and for the collective variable are derived and explicit formulas for transition rates, dynamical forces, mass parameters and friction coefficients are given. The applicability of the formulation in terms of characteristic quantities of nuclear systems is considered in detail and some peculiarities due to memory effects in the initial equilibration process of heavy-ion collisions are discussed. (orig.)

Impact of Small Body Weight on Tenofovir-Associated Renal Dysfunction in HIV-Infected Patients: A Retrospective Cohort Study of Japanese Patients

Science.gov (United States)

Nishijima, Takeshi; Komatsu, Hirokazu; Gatanaga, Hiroyuki; Aoki, Takahiro; Watanabe, Koji; Kinai, Ei; Honda, Haruhito; Tanuma, Junko; Yazaki, Hirohisa; Tsukada, Kunihisa; Honda, Miwako; Teruya, Katsuji; Kikuchi, Yoshimi; Oka, Shinichi

2011-01-01

Background Treatment with tenofovir is sometimes associated with renal dysfunction. Limited information is available on this side effect in patients with small body weight, although the use of tenofovir will spread rapidly in Asia and Africa, where patients are likely to be of smaller body weight. Methods In a single-center cohort, Japanese patients with HIV infection who started tenofovir-containing antiretroviral therapy were retrospectively analyzed. The incidence of tenofovir-associated renal dysfunction, defined as more than 25% decrement of estimated glomerular filtration rate (eGFR) from the baseline, was determined. The effects of small body weight and body mass index (BMI) on tenofovir-associated renal dysfunction, respectively, were estimated in univariate and multivariate Cox hazards models as the primary exposure. Other possible risk factors were evaluated by univariate analysis and those found significant were entered into the multivariate analysis. Results The median weight of 495 patients was 63 kg. Tenofovir-related renal dysfunction occurred in 97 (19.6%) patients (incidence: 10.5 per 100 person-years). Univariate analysis showed that the incidence of tenofovir-related renal dysfunction was significantly associated with smaller body weight and BMI, respectively (per 5 kg decrement, HR = 1.23; 95% CI, 1.10–1.37; pdecrement, HR = 1.14; 95% CI, 1.05–1.23; p = 0.001). Old age, high baseline eGFR, low serum creatinine, low CD4 count, high HIV viral load, concurrent nephrotoxic drugs, hepatitis C infection, and current smoking were also associated with tenofovir-related renal dysfunction. Multivariate analysis identified small body weight as a significant risk (adjusted HR = 1.13; 95% CI, 1.01–1.27; p = 0.039), while small BMI had marginal significance (adjusted HR = 1.07; 95% CI 1.00–1.16; p = 0.058). Conclusion The incidence of tenofovir-associated renal dysfunction in Japanese patients was high. Small body weight

Collision-induced dissociation of aflatoxins.

Science.gov (United States)

Tóth, Katalin; Nagy, Lajos; Mándi, Attila; Kuki, Ákos; Mézes, Miklós; Zsuga, Miklós; Kéki, Sándor

2013-02-28

The aflatoxin mycotoxins are particularly hazardous to health when present in food. Therefore, from an analytical point of view, knowledge of their mass spectrometric properties is essential. The aim of the present study was to describe the collision-induced dissociation behavior of the four most common aflatoxins: B1, B2, G1 and G2. Protonated aflatoxins were produced using atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) combined with high-performance liquid chromatography (HPLC). For the tandem mass spectrometry (MS/MS) experiments nitrogen was used as the collision gas and the collision energies were varied in the range of 9-44 eV (in the laboratory frame). The major APCI-MS/MS fragmentations of protonated aflatoxins occurred at 30 eV collision energy. The main fragmentation channels were found to be the losses of a series of carbon monoxide molecules and loss of a methyl radical, leading to the formation of radical-type product ions. In addition, if the aflatoxin molecule contained an ether- or lactone-oxygen atom linked to a saturated carbon atom, loss of a water molecule was observed from the [M + H](+) ion, especially in the case of aflatoxins G1 and G2. A relatively small modification in the structure of aflatoxins dramatically altered the fragmentation pathways and this was particularly true for aflatoxins B1 and B2. Due to the presence of a C = C double bond connected to the ether group in aflatoxin B1 no elimination of water was observed but, instead, formation of radical-type product ions occurred. Fragmentation of protonated aflatoxin B1 yielded the most abundant radical-type cations. Copyright © 2013 John Wiley & Sons, Ltd.

Electromagnetic fields in small systems from a multiphase transport model

Science.gov (United States)

Zhao, Xin-Li; Ma, Yu-Gang; Ma, Guo-Liang

2018-02-01

We calculate the electromagnetic fields generated in small systems by using a multiphase transport (AMPT) model. Compared to A +A collisions, we find that the absolute electric and magnetic fields are not small in p +Au and d +Au collisions at energies available at the BNL Relativistic Heavy Ion Collider and in p +Pb collisions at energies available at the CERN Large Hadron Collider. We study the centrality dependencies and the spatial distributions of electromagnetic fields. We further investigate the azimuthal fluctuations of the magnetic field and its correlation with the fluctuating geometry using event-by-event simulations. We find that the azimuthal correlation 〈" close="〉cos(ϕα+ϕβ-2 ΨRP)〉">cos2 (ΨB-Ψ2) between the magnetic field direction and the second-harmonic participant plane is almost zero in small systems with high multiplicities, but not in those with low multiplicities. This indicates that the charge azimuthal correlation is not a valid probe to study the chiral magnetic effect (CME) in small systems with high multiplicities. However, we suggest searching for possible CME effects in small systems with low multiplicities.

Manipulating time and space: Collision prediction in peripersonal and extrapersonal space.

Science.gov (United States)

Iachini, Tina; Ruotolo, Francesco; Vinciguerra, Michela; Ruggiero, Gennaro

2017-09-01

Being able to predict potential collisions is a necessary survival prerequisite for all moving species. Temporal and spatial information is fundamental for this purpose. However, it is not clear yet if the peripersonal (i.e. near) and extrapersonal (i.e. far) distance between our body and the moving objects affects the way in which we can predict possible collisions. In order to assess this, we manipulated independently velocity and path of two balls moving one towards the other in such a way as to collide or not in peripersonal and extrapersonal space. In two experiments, participants had to judge if these balls were to collide or not. The results consistently showed a lower discrimination capacity and a more liberal tendency to predict collisions when the moving balls were in peripersonal space and their velocity was different rather than equal. This did not happen in extrapersonal space. Therefore, peripersonal space was particularly affected by temporal information. The possible link between the motor and anticipatory adaptive function of peripersonal space and collision prediction mechanisms is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Installation with magnetic suspension of test bodies for measurement of small forces. Verification of equivalence of inertial and gravitational mass

International Nuclear Information System (INIS)

Kalebin, S.M.

1988-01-01

Torsion installation with magnetic suspension of test bodies for detection of small forces is considered. Installation application for verification of equivalence of inertial and gravitational mass in the case of test body incidence on the Earth (Etvesh experiment) and in the case of their incidene on the Sun (Dicke experiment) is discussed. The total mass of test bodies, produced in the form of cylinders with 3 cm radius, equals 50 kg (one lead body and one copper body); beam radius of test bodies equals 3 cm (the cylinders are tight against one another); ferrite cylinder with 3 cm radius and 10 cm height is used for their suspension in magnetic field. Effect of thermal noise and electromagnetic force disturbances on measurement results is considered. Conducted calculations show that suggested installation enables to improve the accuracy of verifying mentioned equivalence at least by one order and upwards. This suggests that such installation is a matter of interest for experiments on small force detection

Intercellular cancer collisions generate an ejected crystal comet tail effect with fractal interface embryoid body reassembly transformation

International Nuclear Information System (INIS)

Díaz, Jairo A; Murillo, Mauricio F; Barrero, Alvaro

2011-01-01

We have documented self-assembled geometric triangular chiral crystal complexes (GTCHC) and a framework of collagen vascular invariant geometric attractors in cancer tissues. This article shows how this system evolves in time. These structures are incorporated together and evolve in different ways. When the geometric core is stable, and the tissue architecture collapses, fragmented components emerge, which reveal a hidden interior identifying how each molecule is reassembled into the original mold, using one common connection, ie, a fractal self-similarity that guided the system from the beginning. GTCHC complexes generate ejected crystal comet tail effects and produce strange helicity states that arise in the form of spin domain interactions. As the crystal growth vibration stage progresses, biofractal echo images converge in a master-built construction of embryoid bodies with enolase-selective immunopositivity in relation to clusters of triangular chiral cell organization. In our electro-optic collision model, we were able to predict and replicate all the characteristics of this complex geometry that connects a physical phenomenon with the signal patterns that generate biologic chaos. Intrinsically, fractal geometry makes spatial correction errors embrace the chaotic system in a way that permits new structures to emerge, and as a result, an ordered self-assembly of embryoid bodies with neural differentiation at the final stage of cancer development is a predictable process. We hope that further investigation of these structures will lead not only to a new way of thinking about physics and biology, but also to a rewarding area in cancer research

Hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1981-01-01

Qualitative picture of high energy hadron-nucleus collision process, emerging from the analysis of experimental data, is presented. Appropriate description procedure giving a possibility of reproducing various characteristics of this process in terms of the data on elementary hadron-nucleon interaction is proposed. Formula reproducing hadron-nucleus collision cross sections is derived. Inelastic collision cross sections for pion-nucleus and proton-nucleus reactions at wide energy interval are calculated for Pb, Ag, and Al targets. A-dependence of cross sections for pion-nucleus and proton-nucleus collisions at nearly 50 GeV/c momentum were calculated and compared with existing experimental data. Energy dependence of cross sections for hadron-nucleus collisions is determined simply by energy dependence of corresponding cross sections for hadron-nucleon collisions; A-dependence is determined simply by nuclear sizes and nucleon density distributions in nuclei

Kinematic and dynamic pair collision statistics of sedimenting inertial particles relevant to warm rain initiation

International Nuclear Information System (INIS)

Rosa, Bogdan; Parishani, Hossein; Ayala, Orlando; Wang, Lian-Ping; Grabowski, Wojciech W

2011-01-01

In recent years, direct numerical simulation (DNS) approach has become a reliable tool for studying turbulent collision-coalescence of cloud droplets relevant to warm rain development. It has been shown that small-scale turbulent motion can enhance the collision rate of droplets by either enhancing the relative velocity and collision efficiency or by inertia-induced droplet clustering. A hybrid DNS approach incorporating DNS of air turbulence, disturbance flows due to droplets, and droplet equation of motion has been developed to quantify these effects of air turbulence. Due to the computational complexity of the approach, a major challenge is to increase the range of scales or size of the computation domain so that all scales affecting droplet pair statistics are simulated. Here we discuss our on-going work in this direction by improving the parallel scalability of the code, and by studying the effect of large-scale forcing on pair statistics relevant to turbulent collision. New results at higher grid resolutions show a saturation of pair and collision statistics with increasing flow Reynolds number, for given Kolmogorov scales and small droplet sizes. Furthermore, we examine the orientation dependence of pair statistics which reflects an interesting coupling of gravity and droplet clustering.

ZERO IMPACT PARAMETER WHITE DWARF COLLISIONS IN FLASH

International Nuclear Information System (INIS)

Hawley, W. P.; Athanassiadou, T.; Timmes, F. X.

2012-01-01

We systematically explore zero impact parameter collisions of white dwarfs (WDs) with the Eulerian adaptive grid code FLASH for 0.64 + 0.64 M ☉ and 0.81 + 0.81 M ☉ mass pairings. Our models span a range of effective linear spatial resolutions from 5.2 × 10 7 to 1.2 × 10 7 cm. However, even the highest resolution models do not quite achieve strict numerical convergence, due to the challenge of properly resolving small-scale burning and energy transport. The lack of strict numerical convergence from these idealized configurations suggests that quantitative predictions of the ejected elemental abundances that are generated by binary WD collision and merger simulations should be viewed with caution. Nevertheless, the convergence trends do allow some patterns to be discerned. We find that the 0.64 + 0.64 M ☉ head-on collision model produces 0.32 M ☉ of 56 Ni and 0.38 M ☉ of 28 Si, while the 0.81 + 0.81 M ☉ head-on collision model produces 0.39 M ☉ of 56 Ni and 0.55 M ☉ of 28 Si at the highest spatial resolutions. Both mass pairings produce ∼0.2 M ☉ of unburned 12 C+ 16 O. We also find the 0.64 + 0.64 M ☉ head-on collision begins carbon burning in the central region of the stalled shock between the two WDs, while the more energetic 0.81 + 0.81 M ☉ head-on collision raises the initial post-shock temperature enough to burn the entire stalled shock region to nuclear statistical equilibrium.

Lightwave-driven quasiparticle collisions on a sub-cycle timescale

Science.gov (United States)

Langer, F.; Hohenleutner, M.; Schmid, C.; Poellmann, C.; Nagler, P.; Korn, T.; Schüller, C.; Sherwin, M. S.; Huttner, U.; Steiner, J. T.; Koch, S. W.; Kira, M.; Huber, R.

2016-01-01

Ever since Ernest Rutherford first scattered α-particles from gold foils1, collision experiments have revealed unique insights into atoms, nuclei, and elementary particles2. In solids, many-body correlations also lead to characteristic resonances3, called quasiparticles, such as excitons, dropletons4, polarons, or Cooper pairs. Their structure and dynamics define spectacular macroscopic phenomena, ranging from Mott insulating states via spontaneous spin and charge order to high-temperature superconductivity5. Fundamental research would immensely benefit from quasiparticle colliders, but the notoriously short lifetimes of quasiparticles6 have challenged practical solutions. Here we exploit lightwave-driven charge transport7–24, the backbone of attosecond science9–13, to explore ultrafast quasiparticle collisions directly in the time domain: A femtosecond optical pulse creates excitonic electron–hole pairs in the layered dichalcogenide tungsten diselenide while a strong terahertz field accelerates and collides the electrons with the holes. The underlying wave packet dynamics, including collision, pair annihilation, quantum interference and dephasing, are detected as light emission in high-order spectral sidebands17–19 of the optical excitation. A full quantum theory explains our observations microscopically. This approach opens the door to collision experiments with a broad variety of complex quasiparticles and suggests a promising new way of sub-femtosecond pulse generation. PMID:27172045

The First Asymmetry Measurements in High-Energy Polarized Proton-Nucleus Collision at PHENIX-RHIC

Directory of Open Access Journals (Sweden)

Nakagawa Itaru

2017-01-01

Full Text Available The single spin asymmetries in very forward neutron production had been first observed about a decade ago at RHIC in transversely polarized proton + proton collision at √s = 200 GeV. Although neutron production near zero degrees is well described by the one-pion exchange (OPE framework, the OPE appeared to be not satisfactory to describe the observed analyzing power AN. The absorptive correction to the OPE generates the asymmetry as a consequence of a phase shift between the spin flip and non-spin flip amplitudes. However the amplitude predicted by the OPE is too small to explain the large observed asymmetries. Only the model which introduces interference between major pion and small a1-Reggeon exchange amplitudes has been successful in reproducing the experimental data. During RHIC Run-15, RHIC delivered polarized proton collisions with Au and Al for the first time, enabling the exploration of the mechanism of transverse single-spin asymmetries with nuclear collisions. A very striking A-dependence was discovered in very forward neutron production at PHENIX in transversely polarized proton + nucleus collision at √s = 200 GeV. Such a dependence has not been predicted from the existing framework which has been succesful in proton + proton collision. In this report, experimental and theoretical efforts are discussed to disentangle the mysterious A-dependence in the very forward neutron asymmetry.

Electron emission in collisions of intermediate energy ions with atoms

International Nuclear Information System (INIS)

Garibotti, C.R.

1988-01-01

The aim of this work, is the analysis of the processes of electronic emission produced in the collisions of small ions (H + , He ++ ) of intermediate energy (50 a 200 KeV/amu) with light gaseous targets. (A.C.A.G.) [pt

Exclusive photoproduction of Upsilon in pPb collisions at LHC energies

International Nuclear Information System (INIS)

Dutta, Dipanwita; Chudasama, Ruchi; Mohanty, A.K.

2014-01-01

Recent results of exclusive photoproduction of heavy vector mesons at LHC energies by ALICE and LHCb in pp, pPb and PbPb Ultraperipheral collisions (UPC) confirmed the expectations that UPCs are a very promising probe to study the gluon distributions in nucleons and in nuclei at small x. In this work, we have estimated the photoproduction of γ in pPb collisions at √s NN = 5.02 TeV in the framework of perturbative two-gluon exchange formalism employing various parametrization of gluon distributions functions

Analysis of car’s frontal collision against pole

Science.gov (United States)

Ispas, N.; Nastasoiu, M.

2017-10-01

Reducing the effects of traffic accidents over the occupants is a major objective of collision attempts. Impacts between the car and the pole are very dangerous for the physical integrity of the car’s occupants. To minimalize the effects of such events on the passengers of a vehicle, a whole series of efforts by both designers and experienced engineers led to increasingly the vehicles safety. The main aim of these paper is to quantify the influences over the car passengers of loads involved by car against pole collisions using the same car model at different speeds. Also, this kind on occupant influences were study using a small car model. Other goal of the paper was the study of the cars stiffness in frontal collision against the pole. The paper’s experimental results were obtained by support of DSD, Dr. Steffan Datentechnik GmbH - Linz, Austria. The described tests were performed in full test facility of DSD Linz, in “Easter 2016 PC-Crash Seminar”. Cars accelerations, velocities, rotations angles after pole impact were registered and discussed. The novelty of the paper consists in studies referred for the same car model involved in car against pole collisions at different impact speeds. Paper’s conclusions can be future used for car safety improvement.

Signatures of collective flow in high multiplicity pp collisions

CERN Document Server

Kisiel, Adam

2011-01-01

A blast-wave parametrization, including a full set of hadronic resonances, is used to model a small system, with total particle multiplicity comparable to the one measured in the high-multiplicity pp collisions at the LHC. Calculations are preformed for three cases: with negligible, regular and strong radial flow on the blast-wave hypersurface. We investigate the effects of flow on inclusive p_T spectra as well as on 1D and 3D femtoscopic radii for pions. Special emphasis is put on the role of pions from resonance decays. In particular we show that they magnify the flow effects present in the blast-wave stage and significantly influence the shape of the correlation functions. A specific observable, the R^E_out/R^G_side ratio is proposed as a sensitive probe of the collective effects. Model results for the high multiplicity pp collisions, for scenarios with small and large radial flow are compared.

Dust Interactions on Small Solar System Bodies and Technology Considerations for Exploration

Science.gov (United States)

Kobrick, Ryan,; Hoffman, Jeffrey; Pavone, Marco; Street, Kenneth; Rickman, Douglas

2014-01-01

Small-bodies such as asteroids and Mars' moons Phobos and Deimos have relatively unknown regolith environments. It is hypothesized that dust preserved in the regolith on the surfaces will have similar mechanical properties to lunar dust because of similar formation processes from micrometeorite bombardment, low relative gravity for slow settling times, and virtually no weathering because there is no atmosphere. This combination of processes infers that small-body dust particles will be highly angular and retain abrasive properties. The focus of this paper uses the mission architecture and engineering design for an asteroid hopper known as Hedgehog, a spherical spacecraft with several symmetric spikes used to aid with tumbling mobility in a low gravity environment. Dust abrasion considerations are highlighted throughout the paper relating to the lead authors' previous work, but act as an example of one of many important dust or regolith physical properties that need to be considered for future exploration. Measurable regolith properties are summarized in order to identify technologies that may be useful for exploration in terms of scientific return and spacecraft design. Previous instruments are summarized in this paper that could be used on the Hedgehog. Opportunities for hardware payloads are highlighted that include low mass solutions or dualpurpose instruments that can measure regolith or dust properties. Finally, dust mitigation suggestions are made for vehicles of this mobility profile.

Few-body problem in celestial mechanics

Energy Technology Data Exchange (ETDEWEB)

Dermott, S F [Cornell Univ., Ithaca, NY (USA). Center for Radiophysics and Space Research

1984-03-26

The approaches taken by solar system dynamicists to various outstanding problems has changed considerably in recent years. Some problems for which few-body approaches have been tried in the past are now thought to involve collective phenomena. Observed features in Saturn's rings associated with resonances are examples. On the other hand, the problem of the origin of the Kirkwood gaps in the asteroid belt, for which a number of a many-body approaches (involving collisions or gas friction) have been tried, probably has a few-body solution and may involve chaos.

Ultrarelativistic heavy-ion collisions. Proceedings of the International Workshop XXX on Gross Properties of Nuclei and Nuclear Excitations

International Nuclear Information System (INIS)

Buballa, M.; Noerenberg, W.; Schaefer, B.J.; Wambach, J.

2002-01-01

The following topics were dealt with: Experimental results on ultrarelativistic heavy ion collisions, QCD thermodynamics, equilibration in relativistic heavy ion collisions, lattice QCD, space- time evolution and Hanbury-Brown-Twiss correlations, vector meson production, high-p T and small-x physics. (HSI)

Vacuum polarization effects in low-energy muonic atom collisions

International Nuclear Information System (INIS)

Melezhik, V.S.

1995-01-01

We estimate the vacuum polarization (VP) correction to the Coulomb interaction in collisions of muonic atoms. It is shown that the VP effect, amplified by the low-lying virtual state var-epsilon var-theta ∼10 eV, is of the order of ∼1--2 % in the S-wave cross sections for pμ+p collisions as var-epsilon ≤ var-epsilon var-theta . The VP amplitude becomes comparable to the anomalously small pure Coulomb amplitude for the singlet tμ+t scattering as var-epsilon →0 and near the Ramsauer-Townsend minima in the dμ+p and tμ+p scattering

W, Z, Higgs, and their production in hadron collisions: perspectives

International Nuclear Information System (INIS)

Savoy, C.A.

1980-01-01

The disintegration of intermediate vector bosons (Z 0 , W +- ) is first studied: branching ratios, angular distributions, assymmetries. Then we discuss the production of W's and Z and the possibilities to detect some specific final states in antipp collisions, within the energy range foreseen for the machines currently being built. The effects of 'scaling' violation and of radiative corrections in the frame of Q.C.D. are stressed. The second part deals with the production of Higgs bosons in pp and antipp collisions. We consider several possibilities: the associated production of Higgs boson with Z 0 , the coupling of Higgs boson to gluons in the case of very heavy fermions and the possibility of mixing of Higgs with bound states of heavy quarks. In all cases the cross section for Higgs productions are found very small in pp or antipp collisions [fr

Charge-transfer collisions involving few-electron systems

International Nuclear Information System (INIS)

Kirchner, T.

2016-01-01

Ion-atom collision systems that involve more than one electron constitute nonseparable few-body problems, whose full solution is difficult to say the least. At impact energies well below 1 keV/amu an expansion of the stationary scattering wave function in terms of a limited number of products of nuclear and molecular state wave functions (amended to satisfy scattering boundary conditions) is feasible and usually sufficient to obtain accurate charge-transfer cross sections provided the electronic wave functions include configuration interaction. At energies above 1 keV/amu this approach becomes inefficient and close-coupling methods within the semi classical approximation are better suited to treat the problem. For bare-ion collisions from helium target atoms explicit solutions of the two-electron time-dependent Schrödinger equation can be achieved, but are computationally costly and cannot be extended to problems which involve more than two electrons.

Ion-ion collisions

International Nuclear Information System (INIS)

Salzborn, Erhard; Melchert, Frank

2000-01-01

Collisions between ions belong to the elementary processes occurring in all types of plasmas. In this article we give a short overview about collisions involving one-electron systems. For collisions involving multiply-charged ions we limit the discussion to one specific quasi-one-electron system. (author)

Direct photons in heavy-ion collisions

Energy Technology Data Exchange (ETDEWEB)

Baeuchle, Bjoern

2010-12-13

Direct photon emission from heavy-ion collisions has been calculated and compared to available experimental data. Three different models have been combined to extract direct photons from different environments in a heavy-ion collision: Thermal photons from partonic and hadronic matter have been extracted from relativistic, non-viscous 3+1-dimensional hydrodynamic calculations. Thermal and non-thermal photons from hadronic interactions have been calculated from relativistic transport theory. The impact of different physics assumptions about the thermalized matter has been studied. The models used for the determination of photons from both hydrodynamic and transport calculations have been elucidated and their numerical properties tested. The origin of direct photons, itemised by emission stage, emission time, channel and baryon number density, has been investigated for various systems, as have the transverse momentum spectra and elliptic flow patterns of direct photons. Taking into account the full (vacuum) spectral function of the rho-meson decreases the direct photon emission by approximately 10% at low photon transverse momentum. In all systems that have been considered -- heavy-ion collisions at E{sub lab}=35 AGeV and 158 AGeV, (s{sub NN}){sup 1/2}=62.4 GeV, 130 GeV and 200 GeV -- thermal emission from a system with partonic degrees of freedom is greatly enhanced over that from hadronic systems, while the difference between the direct photon yields from a viscous and a non-viscous hadronic system (transport vs. hydrodynamics) is found to be very small. Predictions for direct photon emission in central U+U-collisions at 35 AGeV have been made. (orig.)

Direct photons in heavy-ion collisions

International Nuclear Information System (INIS)

Baeuchle, Bjoern

2010-01-01

Direct photon emission from heavy-ion collisions has been calculated and compared to available experimental data. Three different models have been combined to extract direct photons from different environments in a heavy-ion collision: Thermal photons from partonic and hadronic matter have been extracted from relativistic, non-viscous 3+1-dimensional hydrodynamic calculations. Thermal and non-thermal photons from hadronic interactions have been calculated from relativistic transport theory. The impact of different physics assumptions about the thermalized matter has been studied. The models used for the determination of photons from both hydrodynamic and transport calculations have been elucidated and their numerical properties tested. The origin of direct photons, itemised by emission stage, emission time, channel and baryon number density, has been investigated for various systems, as have the transverse momentum spectra and elliptic flow patterns of direct photons. Taking into account the full (vacuum) spectral function of the rho-meson decreases the direct photon emission by approximately 10% at low photon transverse momentum. In all systems that have been considered -- heavy-ion collisions at E lab =35 AGeV and 158 AGeV, (s NN ) 1/2 =62.4 GeV, 130 GeV and 200 GeV -- thermal emission from a system with partonic degrees of freedom is greatly enhanced over that from hadronic systems, while the difference between the direct photon yields from a viscous and a non-viscous hadronic system (transport vs. hydrodynamics) is found to be very small. Predictions for direct photon emission in central U+U-collisions at 35 AGeV have been made. (orig.)

Hyperthermal (10-500 eV) collisions of noble gases with Ni(100) surface. Comparison between light and heavy atom collisions

International Nuclear Information System (INIS)

Kim, C.

1995-01-01

Collisional events between 10-500 eV atomic beams (He, Ne, Ar, Kr, and Xe) and a Ni(100) surface are investigated by the classical trajectory method. The calculation employs a molecular dynamics approach combined with a Langevin method for treating energy dissipation to infinite solid. We find that low energy collisions of heavy atoms (Xe and Kr) are characterized by extensive many-body interactions with top layer surface atoms. On the other hand, light atom (Ne and He) collisions can be approximated as a sequence of binary collisions even at these energies. Such a difference in the collisional nature gives rise to the following consequences. Low energy heavy atoms transfer energy mostly to the surface atoms during 45 angle collision. They scatter from the surface with a narrow angular distribution centered in a supraspecular direction. The ratio of the scattered to incident particle energy rapidly decreases with increasing beam energy of heavy atoms. The sputtering yield for Ni atoms by heavy atom bombardment increases quite linearly with beam energy, which is attributed to a linear proportionality between the beam energy and the energy transfered to a surface. Near the threshold energy sputtering can occur more efficiently by light atom bombardment. The energy transfer ratio to solid continuously increases with beam energy for light atoms. For heavy projectiles, on the other hand, this ratio reaches a maximum at the energy of ca, 100 eV, above which it stays nearly constant but slightly decreases. ((orig.))

A comparison of different informative vibrotactile forward collision warnings: does the warning need to be linked to the collision event?

Directory of Open Access Journals (Sweden)

Rob Gray

Full Text Available Recent research demonstrates that auditory and vibrotactile forward collision warnings presenting a motion signal (e.g., looming or apparent motion across the body surface can facilitate speeded braking reaction times (BRTs. The purpose of the present study was to expand on this work by directly comparing warning signals in which the motion conveyed was constant across all collision events with signals in which the speed of motion was dependent on the closing velocity (CV. Two experiments were conducted using a simulated car-following task and BRTs were measured. In Experiment 1, increasing intensity (looming vibrotactile signals were presented from a single tactor attached to the driver's waist. When the increase in intensity was CV-linked, BRTs were significantly faster as compared to a no-warning condition, however, they were not significantly different from constant intensity and CV-independent looming warnings. In Experiment 2, a vertical array of three tactors was used to create motion either towards (upwards or away (downwards from the driver's head. When the warning signal presented upwards motion that was CV-linked, BRTs were significantly faster than all other warning types. Downwards warnings led to a significantly higher number of brake activations in false alarm situations as compared to upwards moving warnings. The effectiveness of dynamic tactile collision warnings would therefore appear to depend on both the link between the warning and collision event and on the directionality of the warning signal.

Influence of turbulence on the drop growth in warm clouds, Part I: comparison of numerically and experimentally determined collision kernels

Directory of Open Access Journals (Sweden)

Christoph Siewert

2014-09-01

Full Text Available This study deals with the comparison of numerically and experimentally determined collision kernels of water drops in air turbulence. The numerical and experimental setups are matched as closely as possible. However, due to the individual numerical and experimental restrictions, it could not be avoided that the turbulent kinetic energy dissipation rate of the measurement and the simulations differ. Direct numerical simulations (DNS are performed resulting in a very large database concerning geometric collision kernels with 1470 individual entries. Based on this database a fit function for the turbulent enhancement of the collision kernel is developed. In the experiments, the collision rates of large drops (radius >7.5μm$> 7.5\\,\\text{\\textmu{}m}$ are measured. These collision rates are compared with the developed fit, evaluated at the measurement conditions. Since the total collision rates match well for all occurring dissipation rates the distribution information of the fit could be used to enhance the statistical reliability and for the first time an experimental collision kernel could be constructed. In addition to the collision rates, the drop size distributions at three consecutive streamwise positions are measured. The drop size distributions contain mainly small drops (radius <7.5μm$< 7.5\\,\\text{\\textmu{}m}$. The measured evolution of the drop size distribution is confronted with model calculations based on the newly derived fit of the collision kernel. It turns out that the observed fast evolution of the drop size distribution can only be modeled if the collision kernel for small drops is drastically increased. A physical argument for this amplification is missing since for such small drops, neither DNSs nor experiments have been performed. For large drops, for which a good agreement of the collision rates was found in the DNS and the experiment, the time for the evolution of the spectrum in the wind tunnel is too short to draw

Spatio-temporal patterns and environmental controls of small pelagic fish body condition from contrasted Mediterranean areas

Science.gov (United States)

Brosset, Pablo; Fromentin, Jean-Marc; Van Beveren, Elisabeth; Lloret, Josep; Marques, Virginie; Basilone, Gualtiero; Bonanno, Angelo; Carpi, Piera; Donato, Fortunata; Čikeš Keč, Vanja; De Felice, Andrea; Ferreri, Rosalia; Gašparević, Denis; Giráldez, Ana; Gücü, Ali; Iglesias, Magdalena; Leonori, Iole; Palomera, Isabel; Somarakis, Stylianos; Tičina, Vjekoslav; Torres, Pedro; Ventero, Ana; Zorica, Barbara; Ménard, Frédéric; Saraux, Claire

2017-02-01

Small pelagic fish are among the most ecologically and economically important marine fish species and are characterized by large fluctuations all over the world. In the Mediterranean Sea, low catches and biomass of anchovies and sardines have been described in some areas during the last decade, resulting in important fisheries crises. Therefore, we studied anchovy and sardine body condition variability, a key index of population health and its response to environmental and anthropogenic changes. Wide temporal and spatial patterns were investigated by analyzing separately data from scientific surveys and fisheries in eight Mediterranean areas between 1975 and 2015. Results showed that anchovy and sardine body condition as well as maximum size in some areas sharply decreased in most Mediterranean areas along years (except in the Northern Alboran Sea). Despite this general pattern, well-marked environmental differences between sub-regions were highlighted by several analyses and variations in body condition were not found to be homogeneous over all the Mediterranean Sea. Further, other analyses revealed that except for the Adriatic where major changes towards a lower body condition were concomitant with a decrease in river runoffs and chl-a concentration, no concomitant environmental regime shift was detected in other areas. Together, these analyses highlighted the current poor body condition of almost all small pelagic fish populations in the Mediterranean. Yet, global environmental indices could not explain the observed changes and the general decrease in condition might more likely come from regional environmental and/or anthropogenic (fishing) effects. A prolonged state of poor fish body condition, together with an observed reduced size and early age-at-maturity may have strong ecological, economic and social consequences all around the Mediterranean Sea.

An experimental study on the excitation of large volume airguns in a small volume body of water

International Nuclear Information System (INIS)

Wang, Baoshan; Yang, Wei; Yuan, Songyong; Ge, Hongkui; Chen, Yong; Guo, Shijun; Xu, Ping

2010-01-01

A large volume airgun array is effective in generating seismic waves, which is extensively used in large volume bodies of water such as oceans, lakes and reservoirs. So far, the application of large volume airguns is subject to the distribution of large volume bodies of water. This paper reports an attempt to utilize large volume airguns in a small body of water as a seismic source for seismotectonic studies. We carried out a field experiment in Mapaoquan pond, Fangshan district, Beijing, during the period 25–30 May 2009. Bolt LL1500 airguns, each with volumes of 2000 in 3 , the largest commercial airguns available today, were used in this experiment. We tested the excitation of the airgun array with one or two guns. The airgun array was placed 7–11 m below the water's surface. The near- and far-field seismic motions induced by the airgun source were recorded by a 100 km long seismic profile composed of 16 portable seismometers and a 100 m long strong motion seismograph profile, respectively. The following conclusions can be drawn from this experiment. First, it is feasible to excite large volume airguns in a small volume body of water. Second, seismic signals from a single shot of one airgun can be recognized at the offset up to 15 km. Taking advantage of high source repeatability, we stacked records from 128 shots to enhance the signal-to-noise ratio, and direct P-waves can be easily identified at the offset ∼50 km in stacked records. Third, no detectable damage to fish or near-field constructions was caused by the airgun shots. Those results suggest that large volume airguns excited in small bodies of water can be used as a routinely operated seismic source for mid-scale (tens of kilometres) subsurface explorations and monitoring under various running conditions

Mechanism of ballistic collisions

International Nuclear Information System (INIS)

Sindoni, J.M.; Sharma, R.D.

1992-01-01

Ballistic collisions is a term used to describe atom-diatom collisions during which a substantial fraction of the initial relative translational energy is converted into the internal energy of the diatom. An exact formulation of the impulse approach to atom-diatom collisions is shown to be in excellent agreement with the experimental results for the CsF-Ar system at 1.1 eV relative translational energy for laboratory scattering angles of 30 degree and 60 degree. The differential cross section for scattering of CsF peaks at two distinct recoil velocities. The peak centered at the recoil velocity corresponding to elastic scattering has been called the elastic peak. This peak is shown to consist of several hundred inelastic transitions, most involving a small change in internal energy. The peak near the center-of-mass (c.m.) velocity is called the ballistic peak and is shown to consist of highly inelastic (ballistic) transitions. It is shown that transitions comprising the ballistic (elastic) peak occur when an Ar atom strikes the F (Cs) end of CsF. When one is looking along the direction of the c.m. velocity, the signal from a single transition, which converts about 99.99% of the relative translational energy into internal energy, may be larger than the signal from any other ballistic transition by as much as an order of magnitude. This property may be used to prepare state-selected and velocity-selected beams for further studies. It is also pointed out that the ballistic peak may be observed for any atom-molecule system under appropriate circumstances

Angular momentum coupling in atom-atom collisions

International Nuclear Information System (INIS)

Grosser, J.

1986-01-01

The coupling between the electronic angular momentum and the rotating atom-atom axis in the initial or the final phase of an atom-atom collision is discussed, making use of the concepts of radial and rotational (Coriolis) coupling between different molecular states. The description is based on a limited number of well-understood approximations, and it allows an illustrative geometric representation of the transition from the body fixed to the space fixed motion of the electrons. (orig.)

Fermionic molecular dynamics for ground states and collisions of nuclei

International Nuclear Information System (INIS)

Feldmeier, H.; Bieler, K.; Schnack, J.

1994-08-01

The antisymmetric many-body trial state which describes a system of interacting fermions is parametrized in terms of localized wave packets. The equations of motion are derived from the time-dependent quantum variational principle. The resulting Fermionic Molecular Dynamics (FMD) equations include a wide range of semi-quantal to classical physics extending from deformed Hartree-Fock theory to Newtonian molecular dynamics. Conservation laws are discussed in connection with the choice of the trial state. The model is applied to heavy-ion collisions with which its basic features are illustrated. The results show a great variety of phenomena including deeply inelastic collisions, fusion, incomplete fusion, fragmentation, neck emission, promptly emitted nucleons and evaporation. (orig.)

Does small-bodied salmon spawning activity enhance streambed mobility?

Science.gov (United States)

Hassan, Marwan A.; Tonina, Daniele; Buxton, Todd H.

2015-09-01

Female salmonids bury and lay their eggs in streambeds by digging a pit, which is then covered with sediment from a second pit that is dug immediately upstream. The spawning process alters streambed topography, winnows fine sediment, and mixes sediment in the active layer. The resulting egg nests (redds) contain coarser and looser sediments than those of unspawned streambed areas, and display a dune-like shape with an amplitude and length that vary with fish size, substrate conditions, and flow conditions. Redds increase local bed surface roughness (drag, resulting in lower grain shear stress and less particle mobility. Spawning, also prevents streambed armoring by mixing surface and subsurface material, potentially increasing particle mobility. Here we use two-dimensional hydraulic modeling with detailed prespawning and postspawning bathymetries and field observations to test the effect of spawning by small-bodied salmonids on sediment transport. Our results show that topographical roughness from small salmon redds has negligible effects on shear stress at the reach-unit scale, and limited effects at the local scale. Conversely, results indicate sediment mixing reduces armoring and enhances sediment mobility, which increases potential bed load transport by subsequent floods. River restoration in fish-bearing streams should take into consideration the effects of redd excavation on channel stability. This is particularly important for streams that historically supported salmonids and are the focus of habitat restoration actions.

Global conservation laws and femtoscopy of small systems

International Nuclear Information System (INIS)

Chajecki, Zbigniew; Lisa, Mike

2008-01-01

It is increasingly important to understand, in detail, two-pion correlations measured in p+p and d+A collisions. In particular, one wishes to understand the femtoscopic correlations to compare to similar measurements in heavy-ion collisions. However, in the low-multiplicity final states of these systems, global conservation laws generate significant N-body correlations that project onto the two-pion space in nontrivial ways and complicate the femtoscopic analysis. We discuss a formalism to calculate and account for these correlations in collisions dominated by a single particle species (e.g., pions). We also discuss effects on two-particle correlations between nonidentical particles, the understanding of which may be important in the study of femtoscopic space-time asymmetries

ZERO IMPACT PARAMETER WHITE DWARF COLLISIONS IN FLASH

Energy Technology Data Exchange (ETDEWEB)

Hawley, W. P.; Athanassiadou, T.; Timmes, F. X., E-mail: Wendy.Hawley@asu.edu [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)

2012-11-01

We systematically explore zero impact parameter collisions of white dwarfs (WDs) with the Eulerian adaptive grid code FLASH for 0.64 + 0.64 M {sub Sun} and 0.81 + 0.81 M {sub Sun} mass pairings. Our models span a range of effective linear spatial resolutions from 5.2 Multiplication-Sign 10{sup 7} to 1.2 Multiplication-Sign 10{sup 7} cm. However, even the highest resolution models do not quite achieve strict numerical convergence, due to the challenge of properly resolving small-scale burning and energy transport. The lack of strict numerical convergence from these idealized configurations suggests that quantitative predictions of the ejected elemental abundances that are generated by binary WD collision and merger simulations should be viewed with caution. Nevertheless, the convergence trends do allow some patterns to be discerned. We find that the 0.64 + 0.64 M {sub Sun} head-on collision model produces 0.32 M {sub Sun} of {sup 56}Ni and 0.38 M {sub Sun} of {sup 28}Si, while the 0.81 + 0.81 M {sub Sun} head-on collision model produces 0.39 M {sub Sun} of {sup 56}Ni and 0.55 M {sub Sun} of {sup 28}Si at the highest spatial resolutions. Both mass pairings produce {approx}0.2 M {sub Sun} of unburned {sup 12}C+{sup 16}O. We also find the 0.64 + 0.64 M {sub Sun} head-on collision begins carbon burning in the central region of the stalled shock between the two WDs, while the more energetic 0.81 + 0.81 M {sub Sun} head-on collision raises the initial post-shock temperature enough to burn the entire stalled shock region to nuclear statistical equilibrium.

Experimental investigation of the formation of negative hydrogen ions in collisions between positive ions and atomic or molecular targets

International Nuclear Information System (INIS)

Lattouf, Elie

2013-01-01

The formation of the negative hydrogen ion (H - ) in collisions between a positive ion and a neutral atomic or molecular target is studied experimentally at impact energies of a few keV. The doubly-differential cross sections for H - formation are measured as a function of the kinetic energy and emission angle for the collision systems OH + + Ar and O + + H 2 O at 412 eV/a.m.u. These H - ions can be emitted at high energies (keV) in hard quasi-elastic two-body collisions involving a large momentum transfer to the H center. However, H - anions are preferentially emitted at low energy (eV) due to soft many-body (≥ 2) collisions resulting in a low momentum transfer. The formation of H - ions by electron capture follows excitation or ionization of the molecule. The molecular fragmentation dynamics is modeled to simulate the emission of H - ions. The overall good agreement between the simulation and the experiment leads to the understanding of most of the experimental observations. (author) [fr

Electron transfer, ionization, and excitation in atomic collisions

International Nuclear Information System (INIS)

Winter, T.G.; Alston, S.G.

1992-01-01

The research being carried out at Penn State by Winter and Alston addresses the fundamental processes of electron transfer, ionization, and excitation in ion-atom (and ion-ion) collisions. The focus is on intermediate- and higher-energy collisions, corresponding to proton energies of about 25 kilo-electron-volts (keV) or larger. At intermediate energies, where the transition probabilities are not small, many states must be coupled in a large calculation, while at higher energies, perturbative approaches may be used. Several studies have been carried out in the current three-year period; most of these treat systems with only one or two electrons, so that fewer approximations need be made and the basic collisional mechanisms can be more clearly described

Fragmentation of CO2 into C+ + O+ + O, in collisions with protons

International Nuclear Information System (INIS)

Moretto-Capelle, P.

2000-01-01

The fragmentation of CO 2 has been investigated in 25 keV H + + CO 2 collisions using an electron-ion-ion triple coincidence technique. In this letter we focus on the three-body fragmentation into the C + + O + + O final state. A comparison between the measured correlation of C + ,O + and O momenta and simple kinematic models allows us to demonstrate that in the present case, a rather unexpected two-step process with formation of a CO 2+ ion as an intermediate state occurs. This result is at variance with the conclusions of other authors achieved in collisions of photons and electrons with the dioxide molecule. Kinetic energy release distributions in the two steps of the dissociation process are also deduced from experiment; the distributions found for the fragmentation of CO 2+ into C + + O + are found to be very similar to those measured by other authors in collisions of various particles (photons, multi-charged ions) with CO molecules at high enough collision energy. (author). Letter-to-the-editor

Discrete simulations of spatio-temporal dynamics of small water bodies under varied stream flow discharges

Science.gov (United States)

Daya Sagar, B. S.

2005-01-01

Spatio-temporal patterns of small water bodies (SWBs) under the influence of temporally varied stream flow discharge are simulated in discrete space by employing geomorphologically realistic expansion and contraction transformations. Cascades of expansion-contraction are systematically performed by synchronizing them with stream flow discharge simulated via the logistic map. Templates with definite characteristic information are defined from stream flow discharge pattern as the basis to model the spatio-temporal organization of randomly situated surface water bodies of various sizes and shapes. These spatio-temporal patterns under varied parameters (λs) controlling stream flow discharge patterns are characterized by estimating their fractal dimensions. At various λs, nonlinear control parameters, we show the union of boundaries of water bodies that traverse the water body and non-water body spaces as geomorphic attractors. The computed fractal dimensions of these attractors are 1.58, 1.53, 1.78, 1.76, 1.84, and 1.90, respectively, at λs of 1, 2, 3, 3.46, 3.57, and 3.99. These values are in line with general visual observations.

Discrete simulations of spatio-temporal dynamics of small water bodies under varied stream flow discharges

Directory of Open Access Journals (Sweden)

B. S. Daya Sagar

2005-01-01

Full Text Available Spatio-temporal patterns of small water bodies (SWBs under the influence of temporally varied stream flow discharge are simulated in discrete space by employing geomorphologically realistic expansion and contraction transformations. Cascades of expansion-contraction are systematically performed by synchronizing them with stream flow discharge simulated via the logistic map. Templates with definite characteristic information are defined from stream flow discharge pattern as the basis to model the spatio-temporal organization of randomly situated surface water bodies of various sizes and shapes. These spatio-temporal patterns under varied parameters (λs controlling stream flow discharge patterns are characterized by estimating their fractal dimensions. At various λs, nonlinear control parameters, we show the union of boundaries of water bodies that traverse the water body and non-water body spaces as geomorphic attractors. The computed fractal dimensions of these attractors are 1.58, 1.53, 1.78, 1.76, 1.84, and 1.90, respectively, at λs of 1, 2, 3, 3.46, 3.57, and 3.99. These values are in line with general visual observations.

Firetube model and hadron-hadron collisions

International Nuclear Information System (INIS)

Nazareth, R.A.M.S.; Kodama, T.; Portes Junior, D.A.

1992-01-01

A new version of the fire tube model is developed to describe hadron-hadron collisions at ultrarelativistic energies. Several improvements are introduced in order to include the longitudinal expansion of intermediate fireballs, which remedies the overestimates of the transverse momenta in the previous version. It is found that, within a wide range of incident energies, the model describes well the experimental data for the single particle rapidity distribution, two-body correlations in the pseudo-rapidity, transverse momentum spectra of pions and kaons, the leading particle spectra and the K/π ratio. (author)

Cosmic bubble and domain wall instabilities III: the role of oscillons in three-dimensional bubble collisions

Energy Technology Data Exchange (ETDEWEB)

Bond, J. Richard; Braden, Jonathan [CITA, University of Toronto, 60 St. George Street, Toronto, ON, M5S 3H8 (Canada); Mersini-Houghton, Laura, E-mail: bond@cita.utoronto.ca, E-mail: j.braden@ucl.ac.uk, E-mail: mersini@physics.unc.edu [Department of Physics and Astronomy, University of North Carolina-Chapel Hill, NC 27599-3255 (United States)

2015-09-01

We study collisions between pairs of bubbles nucleated in an ambient false vacuum. For the first time, we include the effects of small initial (quantum) fluctuations around the instanton profiles describing the most likely initial bubble profile. Past studies of this problem neglect these fluctuations and work under the assumption that the collisions posess an exact SO(2,1) symmetry. We use three-dimensional lattice simulations to demonstrate that for double-well potentials, small initial perturbations to this symmetry can be amplified as the system evolves. Initially the amplification is well-described by linear perturbation theory around the SO(2,1) background, but the onset of strong nonlinearities amongst the fluctuations quickly leads to a drastic breaking of the original SO(2,1) symmetry and the production of oscillons in the collision region. We explore several single-field models, and we find it is hard to both realize inflation inside of a bubble and produce oscillons in a collision. Finally, we extend our results to a simple two-field model. The additional freedom allowed by the second field allows us to construct viable inflationary models that allow oscillon production in collisions. The breaking of the SO(2,1) symmetry allows for a new class of observational signatures from bubble collisions that do not posess azimuthal symmetry, including the production of gravitational waves which cannot be supported by an SO(2,1) spacetime.

Direct photon production and jet energy-loss in small systems

Energy Technology Data Exchange (ETDEWEB)

Shen, Chun; Park, Chanwook [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada); Paquet, Jean-François [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada); Department of Physics & Astronomy, Stony Brook University, Stony Brook, NY 11733 (United States); Denicol, Gabriel S. [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada); Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Jeon, Sangyong; Gale, Charles [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada)

2016-12-15

Two types of penetrating probes, direct photon and QCD jets, are investigated in the background of a small and rapidly expanding droplet of quark-gluon plasma. The additional thermal electromagnetic radiation results in a ∼50% enhancement of the direct photons. In high multiplicity p+Pb collisions, jets can lose a sizeable fraction of their initial energy, leading to a charged hadron R{sub pA} of ∼0.8 at a transverse momentum around 10 GeV. Those two proposed measurements can help understand the apparent collective behaviour observed in small collision systems.

Semiclassical model of atomic collisions: stopping and capture of the heavy charged particles and exotic atom formation

International Nuclear Information System (INIS)

Beck, W.A.

2000-01-01

The semiclassical model of atomic collisions, especially in different areas of the maximum stopping, when proton collides at the velocity of the boron order velocity, providing as the result for interactions of many bodies with an electron target, enabling application of the model with high degree of confidence to a clearly expressed experimental problem, such the antiproton capture on helium, is presented. The semiclassical collision model and stopping energy are considered. The stopping and capture of negatively-charged particles are investigated. The capture and angular moments of antiprotons, captures at the end of the collision cascade, are presented [ru

Probability of satellite collision

Science.gov (United States)

Mccarter, J. W.

1972-01-01

A method is presented for computing the probability of a collision between a particular artificial earth satellite and any one of the total population of earth satellites. The collision hazard incurred by the proposed modular Space Station is assessed using the technique presented. The results of a parametric study to determine what type of satellite orbits produce the greatest contribution to the total collision probability are presented. Collision probability for the Space Station is given as a function of Space Station altitude and inclination. Collision probability was also parameterized over miss distance and mission duration.

Body lift, drag and power are relatively higher in large-eared than in small-eared bat species.

Science.gov (United States)

Håkansson, Jonas; Jakobsen, Lasse; Hedenström, Anders; Johansson, L Christoffer

2017-10-01

Bats navigate the dark using echolocation. Echolocation is enhanced by external ears, but external ears increase the projected frontal area and reduce the streamlining of the animal. External ears are thus expected to compromise flight efficiency, but research suggests that very large ears may mitigate the cost by producing aerodynamic lift. Here we compare quantitative aerodynamic measures of flight efficiency of two bat species, one large-eared ( Plecotus auritus ) and one small-eared ( Glossophaga soricina ), flying freely in a wind tunnel. We find that the body drag of both species is higher than previously assumed and that the large-eared species has a higher body drag coefficient, but also produces relatively more ear/body lift than the small-eared species, in line with prior studies on model bats. The measured aerodynamic power of P. auritus was higher than predicted from the aerodynamic model, while the small-eared species aligned with predictions. The relatively higher power of the large-eared species results in lower optimal flight speeds and our findings support the notion of a trade-off between the acoustic benefits of large external ears and aerodynamic performance. The result of this trade-off would be the eco-morphological correlation in bat flight, with large-eared bats generally adopting slow-flight feeding strategies. © 2017 The Author(s).

Fast ion-atom and ion-molecule collisions

CERN Document Server

2013-01-01

The principal goal of this book is to provide state-of-the art coverage of the non-relativistic three- and four-body theories at intermediate and high energy ion-atom and ion-molecule collisions. The focus is on the most frequently studied processes: electron capture, ionization, transfer excitation and transfer ionization. The content is suitable both for graduate students and experienced researchers. For these collisions, the literature has seen enormous renewal of activity in the development and applications of quantum-mechanical theories. This subject is of relevance in several branches of science and technology, like accelerator-based physics, the search for new sources of energy and high temperature fusion of light ions. Other important applications are in life sciences via medicine, where high-energy ion beams are used in radiotherapy for which a number of storage ring accelerators are in full operation, under construction or planned to be built worldwide. Therefore, it is necessary to review this fiel...

Modeling and Testing of Phase Transition-Based Deployable Systems for Small Body Sample Capture

Science.gov (United States)

Quadrelli, Marco; Backes, Paul; Wilkie, Keats; Giersch, Lou; Quijano, Ubaldo; Keim, Jason; Mukherjee, Rudranarayan

2009-01-01

This paper summarizes the modeling, simulation, and testing work related to the development of technology to investigate the potential that shape memory actuation has to provide mechanically simple and affordable solutions for delivering assets to a surface and for sample capture and return. We investigate the structural dynamics and controllability aspects of an adaptive beam carrying an end-effector which, by changing equilibrium phases is able to actively decouple the end-effector dynamics from the spacecraft dynamics during the surface contact phase. Asset delivery and sample capture and return are at the heart of several emerging potential missions to small bodies, such as asteroids and comets, and to the surface of large bodies, such as Titan.

ALICE event display of a Pb-Pb collision at 2.76A TeV

CERN Multimedia

AUTHOR|(SzGeCERN)740940; Andronic, Anton

2015-01-01

One of the first lead-lead collisions at the Large Hadron Collider, recorded by the ALICE detector in November 2010. In this collision of lead nuclei at a small impact parameter (central collision), 1209 positively-charged (darker tracks) and 1197 negatively-charged (lighter tracks) particles are produced, about 80 percent are pions. The curvature of a track in the magnetic field of ALICE (0.5 T) is inversely proportional to the momentum of the particle. The cylinder is the Time Projection Chamber of ALICE, with a diameter of 5 m and a length of 5 m, recording the charged particles in three dimensions with the equivalent of 500 million pixels.

Nuclear de-excitation processes following medium energy heavy ion collisions

International Nuclear Information System (INIS)

Blann, M.

1986-09-01

As heavy ion reaction studies have progressed from beam energies below 10 MeV/nucleon to higher energies, many non-equilibrium reaction phenomena have been observed. Among these are nucleon emission with velocities in excess of the beam velocity, incomplete momentum transfer to evaporation residue and fission-like fragments, γ-rays with energies in excess of 100 MeV, and π 0 production when beam energies are below the threshold for production by the nucleon-nucleon collision mechanism. Additionally, prefission neutrons have been observed in excess of numbers expected from equilibrium models. A few of the approaches which have been applied to these phenomena are as follows: Intranuclear cascade: two body collisions are assumed to mediate the equilibration. The geometry and momentum space is followed semiclassically. The approach has many successes though it may suffer in a few applications is not following holes; TDHF considers one body processes only; in the energy regime of interest, two body processes are important so that this may not be a viable approach; Boltzmann-Uehling-Uhlenbeck or Vlasov-Uehling-Uhlenbeck (BUU/VUU) equations combine both one body and two body dynamics. The spatial and momentum evolution of the reactions are followed in a mean field. These should be the Cadillacs of the models. They are computationally tedious, and sometimes significant approximations are made in order to achieve computational tract ability; models of collective deceleration. A very simple model approach is discussed to interpret these phenomena, the Boltzmann master equation (BME). The hybrid model was the first to be applied to the question of heavy ion precompound decay, and the BME second. 26 refs., 5 figs., 2 tabs

FAST RADIO BURSTS: COLLISIONS BETWEEN NEUTRON STARS AND ASTEROIDS/COMETS

Energy Technology Data Exchange (ETDEWEB)

Geng, J. J.; Huang, Y. F., E-mail: hyf@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210046 (China)

2015-08-10

Fast radio bursts (FRBs) are newly discovered radio transient sources. Their high dispersion measures indicate an extragalactic origin. However, due to the lack of observational data in other wavelengths, their progenitors still remain unclear. Here we suggest that the collisions between neutron stars (NSs) and asteroids/comets are promising mechanisms for FRBs. During the impact process, a hot plasma fireball forms after the material of the small body penetrates into the NS surface. The ionized matter inside the fireball then expands along the magnetic field lines. Coherent radiation from the thin shell at the top of the fireball will account for the observed FRBs. Our scenario can reasonably explain the main features of FRBs, such as their durations, luminosities, and the event rate. We argue that for a single NS, FRBs are not likely to happen repeatedly in a forseeable timespan since such impacts are of low probability. We predict that faint remnant X-ray emissions should be associated with FRBs, but it may be too faint to be detected by detectors at work.

FAST RADIO BURSTS: COLLISIONS BETWEEN NEUTRON STARS AND ASTEROIDS/COMETS

International Nuclear Information System (INIS)

Geng, J. J.; Huang, Y. F.

2015-01-01

Fast radio bursts (FRBs) are newly discovered radio transient sources. Their high dispersion measures indicate an extragalactic origin. However, due to the lack of observational data in other wavelengths, their progenitors still remain unclear. Here we suggest that the collisions between neutron stars (NSs) and asteroids/comets are promising mechanisms for FRBs. During the impact process, a hot plasma fireball forms after the material of the small body penetrates into the NS surface. The ionized matter inside the fireball then expands along the magnetic field lines. Coherent radiation from the thin shell at the top of the fireball will account for the observed FRBs. Our scenario can reasonably explain the main features of FRBs, such as their durations, luminosities, and the event rate. We argue that for a single NS, FRBs are not likely to happen repeatedly in a forseeable timespan since such impacts are of low probability. We predict that faint remnant X-ray emissions should be associated with FRBs, but it may be too faint to be detected by detectors at work

On the Lippmann--Schwinger equation for atom--diatom collisions: A rotating frame treatment

International Nuclear Information System (INIS)

Kouri, D.J.; Heil, T.G.; Shimoni, Y.

1976-01-01

The use of a rotating frame description of molecular collisions is reconsidered within the framework of the Lippmann--Schwinger equation for the transition or T operator. The present approach explicitly displays the proper boundary conditions which apply to descriptions of such collisions in the rotating frame whose Z axis follows the scattering vector. The resulting body frame equations are shown to lead naturally to the introduction of ''body frame Bessel and Hankel functions,'' J/subJ//subj//sup lambda//sup lambda//sup prime/ and H/subJ//subj//sup lambda//sup lambda//sup prime/ (BFBF), which are solutions of the unperturbed Hamiltonian for the collision transformed to the rotating frame. It is found that the BFBF can be defined in several ways differing by phase factors that affect their asymptotic form. Two particular choices are examined, one of which leads to a simple asymptotic form of the wavefunction, and the other leads to a somewhat more complicated form. Both are shown to yield the j/subz/-conserving coupled states equations of McGuire and Kouri but slightly different approximations are required in the two cases. The implication of these results as to the accuracy of the j/subz/CCS method are discussed

[Spatial heterogeneity in body condition of small yellow croaker in Yellow Sea and East China Sea based on mixed-effects model and quantile regression analysis].

Science.gov (United States)

Liu, Zun-Lei; Yuan, Xing-Wei; Yan, Li-Ping; Yang, Lin-Lin; Cheng, Jia-Hua

2013-09-01

By using the 2008-2010 investigation data about the body condition of small yellow croaker in the offshore waters of southern Yellow Sea (SYS), open waters of northern East China Sea (NECS), and offshore waters of middle East China Sea (MECS), this paper analyzed the spatial heterogeneity of body length-body mass of juvenile and adult small yellow croakers by the statistical approaches of mean regression model and quantile regression model. The results showed that the residual standard errors from the analysis of covariance (ANCOVA) and the linear mixed-effects model were similar, and those from the simple linear regression were the highest. For the juvenile small yellow croakers, their mean body mass in SYS and NECS estimated by the mixed-effects mean regression model was higher than the overall average mass across the three regions, while the mean body mass in MECS was below the overall average. For the adult small yellow croakers, their mean body mass in NECS was higher than the overall average, while the mean body mass in SYS and MECS was below the overall average. The results from quantile regression indicated the substantial differences in the allometric relationships of juvenile small yellow croakers between SYS, NECS, and MECS, with the estimated mean exponent of the allometric relationship in SYS being 2.85, and the interquartile range being from 2.63 to 2.96, which indicated the heterogeneity of body form. The results from ANCOVA showed that the allometric body length-body mass relationships were significantly different between the 25th and 75th percentile exponent values (F=6.38, df=1737, P<0.01) and the 25th percentile and median exponent values (F=2.35, df=1737, P=0.039). The relationship was marginally different between the median and 75th percentile exponent values (F=2.21, df=1737, P=0.051). The estimated body length-body mass exponent of adult small yellow croakers in SYS was 3.01 (10th and 95th percentiles = 2.77 and 3.1, respectively). The

INITIAL PLANETESIMAL SIZES AND THE SIZE DISTRIBUTION OF SMALL KUIPER BELT OBJECTS

International Nuclear Information System (INIS)

Schlichting, Hilke E.; Fuentes, Cesar I.; Trilling, David E.

2013-01-01

The Kuiper Belt is a remnant from the early solar system and its size distribution contains many important constraints that can be used to test models of planet formation and collisional evolution. We show, by comparing observations with theoretical models, that the observed Kuiper Belt size distribution is well matched by coagulation models, which start with an initial planetesimal population with radii of about 1 km, and subsequent collisional evolution. We find that the observed size distribution above R ∼ 30 km is primordial, i.e., it has not been modified by collisional evolution over the age of the solar system, and that the size distribution below R ∼ 30 km has been modified by collisions and that its slope is well matched by collisional evolution models that use published strength laws. We investigate in detail the resulting size distribution of bodies ranging from 0.01 km to 30 km and find that its slope changes several times as a function of radius before approaching the expected value for an equilibrium collisional cascade of material strength dominated bodies for R ∼< 0.1 km. Compared to a single power-law size distribution that would span the whole range from 0.01 km to 30 km, we find in general a strong deficit of bodies around R ∼ 10 km and a strong excess of bodies around 2 km in radius. This deficit and excess of bodies are caused by the planetesimal size distribution left over from the runaway growth phase, which left most of the initial mass in small planetesimals while only a small fraction of the total mass is converted into large protoplanets. This excess mass in small planetesimals leaves a permanent signature in the size distribution of small bodies that is not erased after 4.5 Gyr of collisional evolution. Observations of the small Kuiper Belt Object (KBO) size distribution can therefore test if large KBOs grew as a result of runaway growth and constrained the initial planetesimal sizes. We find that results from recent KBO

Collision Mechanics

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Servis, D.P.; Zhang, Shengming

1999-01-01

The first section of the present report describes the procedures that are being programmed at DTU for evaluation of the external collision dynamics. Then follows a detailed description of a comprehensive finite element analysis of one collision scenario for MS Dextra carried out at NTUA. The last...

A comparison of methods for evaluating structure during ship collisions

International Nuclear Information System (INIS)

Ammerman, D.J.; Daidola, J.C.

1996-01-01

A comparison is provided of the results of various methods for evaluating structure during a ship-to-ship collision. The baseline vessel utilized in the analyses is a 67.4 meter in length displacement hull struck by an identical vessel traveling at speeds ranging from 10 to 30 knots. The structural response of the struck vessel and motion of both the struck and striking vessels are assessed by finite element analysis. These same results are then compared to predictions utilizing the open-quotes Tanker Structural Analysis for Minor Collisionsclose quotes (TSAMC) Method, the Minorsky Method, the Haywood Collision Process, and comparison to full-scale tests. Consideration is given to the nature of structural deformation, absorbed energy, penetration, rigid body motion, and virtual mass affecting the hydrodynamic response. Insights are provided with regard to the calibration of the finite element model which was achievable through utilizing the more empirical analyses and the extent to which the finite element analysis is able to simulate the entire collision event. 7 refs., 8 figs., 4 tabs

Orbit-attitude coupled motion around small bodies: Sun-synchronous orbits with Sun-tracking attitude motion

Science.gov (United States)

Kikuchi, Shota; Howell, Kathleen C.; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

2017-11-01

The motion of a spacecraft in proximity to a small body is significantly perturbed due to its irregular gravity field and solar radiation pressure. In such a strongly perturbed environment, the coupling effect of the orbital and attitude motions exerts a large influence that cannot be neglected. However, natural orbit-attitude coupled dynamics around small bodies that are stationary in both orbital and attitude motions have yet to be observed. The present study therefore investigates natural coupled motion that involves both a Sun-synchronous orbit and Sun-tracking attitude motion. This orbit-attitude coupled motion enables a spacecraft to maintain its orbital geometry and attitude state with respect to the Sun without requiring active control. Therefore, the proposed method can reduce the use of an orbit and attitude control system. This paper first presents analytical conditions to achieve Sun-synchronous orbits and Sun-tracking attitude motion. These analytical solutions are then numerically propagated based on non-linear coupled orbit-attitude equations of motion. Consequently, the possibility of implementing Sun-synchronous orbits with Sun-tracking attitude motion is demonstrated.

First LHCb results from pA and Pb-Pb collisions

CERN Document Server

Massacrier, L.

2016-09-21

In 2015, the LHCb collaboration endorsed the proposal to pursue an ambitious heavy-ion physics program. In 2013, LHCb has demonstrated its capabilities to operate successfully in p-Pb and Pb-p collisions, leading already to several important publications in the field. The measurements of the nuclear modification factor and forward-backward production of prompt and displaced J/$\\psi$, $\\psi$(2S) and $\\Upsilon$(1S) states, as well as the production of prompt $D^{0}$ mesons, have allowed to extend the knowledge of Cold Nuclear Matter effects on open heavy flavours and quarkonium production. The measurement of Z-boson production, important to constrain nuclear PDFs, and the measurement of two-particle angular correlations, probing collective effects in the dense environment of high energy collisions, have also been performed. Furthermore, LHCb is the only experiment at the LHC that can be operated in fixed-target mode, owing to the injection of a small amount of gas inside the LHCb collision area. There have been...

Theoretical Investigation of Kinetic Processes in Small Radicals of Importance in Combustion

Energy Technology Data Exchange (ETDEWEB)

Alexander, Millard [Univ. of Maryland, College Park, MD (United States). Dept. of Chemistry and Biochemistry; Dagdigian, Paul J. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry

2017-12-12

Our group studies inelastic and reactive collisions of small molecules, focusing on radicals important in combustion environments. The goal is the better understanding of kinetic processes that may be difficult to access experimentally. An essential component is the accurate determination and fitting of potential energy surfaces (PESs). After fitting the ab initio points to obtain global PESs, we treat the dynamics using time-independent (close-coupling) methods. Cross sections and rate constants for collisions of are determined with our Hibridon program suite . We have studied energy transfer (rotationally, vibrationally, and/or electronically inelastic) in small hydrocarbon radicals (CH₂ and CH₃) and the CN radical. We have made a comparison with experimental measurements of relevant rate constants for collisions of these radicals. Also, we have calculated accurate transport properties using state-of-the-art PESs and to investigate the sensitivity to these parameters in 1-dimensional flame simulations. Of particular interest are collision pairs involving the light H atom.

SU-F-BRD-11: A Virtual Simulator Designed for Collision Prevention in Proton Therapy

International Nuclear Information System (INIS)

Jung, H; Kum, O; Park, H; Choi, D; Han, Y

2015-01-01

Purpose: In proton therapy, collisions between patient and nozzle potentially occur in attaining minimal air gap due to the large nozzle structure. Thus, we developed software predicting the collisions of the nozzle and patient by simulating treatments. Methods: 3D modeling of a gantry inner-floor, nozzle and robotic-couch was done by using the SolidWorks based on the manufacturer’s machine data. To obtain patient body information, a 3D-scanner was utilized to scan a patient right before CT scanning. From the acquired images, a 3D-image of the patient’s body contour was reconstructed. The accuracy of the image was confirmed against the CT image for a humanoid phantom. The machine components and the virtual patient were combined on the treatment-room coordinate system, resulting in a virtual simulator. The simulator simulated the motion of its components such as rotation and translation of gantry, nozzle and couch, in real scale. Collision, if any, was examined both in static mode and dynamic mode. The static mode checks only at fixed positions of the machine’s components while dynamic mode examines while one component is in motion. Collision was notified if any voxel of two components, for example a nozzle and a patient or couch, overlapped when calculating volume locations. The event and collision point are visualized and colliding volumes are reported. Results: All components were successfully assembled and the motions could be accurately controlled. The 3D-shape of a phantom agreed with CT images within a deviation of 2 mm. Collision situations can be simulated within minutes and the results are displayed and reported. Conclusion: The developed software will be useful in improving patient safety and clinical efficiency for proton therapy. This work was supported by the National Research Foundation of Korea funded by Ministry of Science, ICT & Future Planning (2012M3A9B6055201, 2013M2A2A7043507), and Samsung Medical Center grant (GFO1130081)

Studies of Fluctuation Processes in Nuclear Collisions

Energy Technology Data Exchange (ETDEWEB)

Ayik, Sakir [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

2016-04-14

The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and

Measurement of muon tagged open heavy flavor production in Pb+Pb collisions at 2.76 TeV with ATLAS

CERN Document Server

Perepelitsa, D V; The ATLAS collaboration

2012-01-01

Bottom quark is a very important probe to study the hot, dense medium produced in the heavy ion collisions. Bottom quark is produced at the relatively early stage of the nucleus-nucleus collisions and may have a small gluon radiation due to a suppression of small angle gluon radiation `dead cone effect’. Because the heavy mass of b-hadrons, muons from semi-leptonic b-hadron decays tend to have larger angle with respect to the jet axis. This information can be used to tag b-jets. Specifically, the transverse momentum of the muon with respect to the b-jet axis, pT^{rel}, is used to differentiate b-jets from the background charm and light quark jets. In this talk, we present the b-jet suppression R_CP, which is defined as the ratio of the average N_coll scaled yield in central collisions to that in peripheral collisions (60-80%), as a function of the muon momentum, jet momentum and the number of participants average N_part in Pb+Pb collisions at 2.76 TeV. The result is also compared with the inclusive heavy fl...

An existence proof of a symmetric periodic orbit in the octahedral six-body problem

OpenAIRE

Cavalcanti, Anete Soares

2016-01-01

We present a proof of the existence of a periodic orbit for the Newtonian six-body problem with equal masses. This orbit has three double collisions each period and no multiple collisions. Our proof is based on the minimization of the Lagrangian action functional on a well chosen class of symmetric loops.

Spin Interaction under the Collision of Two Kerr-(Anti-de Sitter Black Holes

Directory of Open Access Journals (Sweden)

Bogeun Gwak

2017-12-01

Full Text Available We investigate herein the spin interaction during collisions between Kerr-(anti-de Sitter black holes. The spin interaction potential depends on the relative rotation directions of the black holes, and this potential can be released as gravitational radiation upon collision. The energy of the radiation depends on the cosmological constant and corresponds to the spin interaction potential in the limit that one of the black holes has negligibly small mass and angular momentum. We then determine the approximate overall behaviors of the upper bounds on the radiation using thermodynamics. The results indicate that the spin interaction can consistently contribute to the radiation. In addition, the radiation depends on the stability of the black hole produced by the collision.

Including collisions in gyrokinetic tokamak and stellarator simulations

International Nuclear Information System (INIS)

Kauffmann, Karla

2012-01-01

TEMs in a tokamak configuration. The results show that collisions reduce the growth rate of slab ITGs in cylinder geometry, whereas they do not affect ITGs in a tokamak, which are mainly curvature-driven. However it is important to note that the pitch-angle scattering operator does not conserve momentum, which is most critical in the parallel direction. Therefore, the damping found in a cylinder could be the consequence of this missing feature and not a physical result [Dimits and Cohen 1994]. Nonetheless, the results are useful to determine whether the instability is mainly being driven by a slab or toroidal ITG mode. EUTERPE also has the feature of including kinetic electrons, which made simulations of TEMs with collisions possible. The combination of collisions and kinetic electrons made the numerical calculations extremely time-consuming, since the time step had to be small enough to resolve the fast electron motion. In contrast to the ITG results, it was observed that collisions are extremely important for TEMs in a tokamak, and in some special cases, depending on whether they were mainly driven by density or temperature gradients, collisions could even suppress the mode (in agreement with [Angioni et al. 2005, Connor et al. 2006]). In the case of stellarators it was found that ITGs are highly dependent on the device configuration. For LHD it was shown that collisions slightly reduce the growth rate of the instability, but for Wendelstein 7-X they do not affect it and the growth rate showed a similar trend with collisionality to that of the tokamak case. Collisions also tend to make the ballooning structure of the modes less pronounced.

Including collisions in gyrokinetic tokamak and stellarator simulations

Energy Technology Data Exchange (ETDEWEB)

Kauffmann, Karla

2012-04-10

ITGs and TEMs in a tokamak configuration. The results show that collisions reduce the growth rate of slab ITGs in cylinder geometry, whereas they do not affect ITGs in a tokamak, which are mainly curvature-driven. However it is important to note that the pitch-angle scattering operator does not conserve momentum, which is most critical in the parallel direction. Therefore, the damping found in a cylinder could be the consequence of this missing feature and not a physical result [Dimits and Cohen 1994]. Nonetheless, the results are useful to determine whether the instability is mainly being driven by a slab or toroidal ITG mode. EUTERPE also has the feature of including kinetic electrons, which made simulations of TEMs with collisions possible. The combination of collisions and kinetic electrons made the numerical calculations extremely time-consuming, since the time step had to be small enough to resolve the fast electron motion. In contrast to the ITG results, it was observed that collisions are extremely important for TEMs in a tokamak, and in some special cases, depending on whether they were mainly driven by density or temperature gradients, collisions could even suppress the mode (in agreement with [Angioni et al. 2005, Connor et al. 2006]). In the case of stellarators it was found that ITGs are highly dependent on the device configuration. For LHD it was shown that collisions slightly reduce the growth rate of the instability, but for Wendelstein 7-X they do not affect it and the growth rate showed a similar trend with collisionality to that of the tokamak case. Collisions also tend to make the ballooning structure of the modes less pronounced.

Absolute quantitative total-body small-animal SPECT with focusing pinholes

International Nuclear Information System (INIS)

Wu, Chao; Have, Frans van der; Vastenhouw, Brendan; Beekman, Freek J.; Dierckx, Rudi A.J.O.; Paans, Anne M.J.

2010-01-01

In pinhole SPECT, attenuation of the photon flux on trajectories between source and pinholes affects quantitative accuracy of reconstructed images. Previously we introduced iterative methods that compensate for image degrading effects of detector and pinhole blurring, pinhole sensitivity and scatter for multi-pinhole SPECT. The aim of this paper is (1) to investigate the accuracy of the Chang algorithm in rodents and (2) to present a practical Chang-based method using body outline contours obtained with optical cameras. Here we develop and experimentally validate a practical method for attenuation correction based on a Chang first-order method. This approach has the advantage that it is employed after, and therefore independently from, iterative reconstruction. Therefore, no new system matrix has to be calculated for each specific animal. Experiments with phantoms and animals were performed with a high-resolution focusing multi-pinhole SPECT system (U-SPECT-II, MILabs, The Netherlands). This SPECT system provides three additional optical camera images of the animal for each SPECT scan from which the animal contour can be estimated. Phantom experiments demonstrated that an average quantification error of -18.7% was reduced to -1.7% when both window-based scatter correction and Chang correction based on the body outline from optical images were applied. Without scatter and attenuation correction, quantification errors in a sacrificed rat containing sources with known activity ranged from -23.6 to -9.3%. These errors were reduced to values between -6.3 and +4.3% (with an average magnitude of 2.1%) after applying scatter and Chang attenuation correction. We conclude that the modified Chang correction based on body contour combined with window-based scatter correction is a practical method for obtaining small-animal SPECT images with high quantitative accuracy. (orig.)

Solvent neurotoxicity in vehicle collision repair workers in New Zealand.

Science.gov (United States)

Keer, Samuel; Glass, Bill; Prezant, Bradley; McLean, David; Pearce, Neil; Harding, Elizabeth; Echeverria, Diana; McGlothlin, James; Babbage, Duncan R; Douwes, Jeroen

2016-12-01

To assess whether solvent use and workplace practices in the vehicle collision repair industry are associated with symptoms of neurotoxicity in spray painters and panel beaters (auto body repair workers). Neurobehavioural symptoms were assessed using a cross-sectional study design in 370 vehicle collision repair and 211 reference workers using the EUROQUEST questionnaire. Full-shift airborne solvent levels were measured in a subset (n=92) of collision repair workers. Solvent exposures were higher in spray painters than in panel beaters, but levels were below current international exposure standards. Collision repair workers were more likely to report symptoms of neurotoxicity than reference workers with ORs of 2.0, 2.4 and 6.4 (all p<0.05) for reporting ≥5, ≥10 and ≥15 symptoms respectively. This trend was generally strongest for panel beaters (ORs of 2.1, 3.3 and 8.2 for ≥5, ≥10 and ≥15 symptoms respectively). Associations with specific symptom domains showed increased risks for neurological (OR 4.2), psychosomatic (OR 3.2), mood (OR 2.1), memory (OR 2.9) and memory and concentration symptoms combined (OR 2.4; all p<0.05). Workers who had worked for 10-19 years or 20+ years in the collision repair industry reported consistently more symptoms than those who had only worked less than 10 years even after adjusting for age. However, those who worked more than 20 years generally reported fewer symptoms than those who worked 10-19 years, suggesting a possible healthy worker survivor bias. Despite low airborne solvent exposures, vehicle collision repair spray painters and panel beaters continue to be at risk of symptoms of neurotoxicity. Copyright © 2016 Elsevier B.V. All rights reserved.

Atomic collisions by neutrons-induced charged particles in water, protein and nucleic acid

International Nuclear Information System (INIS)

Bergman, R.

1976-01-01

The action of slow charged particles is peculiar in that atomic collisions are commonly invlolved. In atomic collisions, which are rare events when fast particles interact with matter, displacement of atoms and chemical bond-breakage is possible. Sufficiently energetic neutrons generate charged recoil particles in matter. Some of these are slow as compared to orbital electrons, but the energy transferred to such slow particles is generally relatively small. Yet, it contributes significantly to the dose absorbed from 0.1-30 keV neutrons. In tissue all recoils induced by neutrons of less than 30 keV are slow, and above 0.1 keV the absorbed dose due to collisiondominates over that due to capture reactions. The aim of the present paper is to identify those intervals of neutron energy in which atomic collision damage is most probable in living matter. The results of calculations presented here indicate that atomic collisions should be most significant for 0.5-3 keV neutrons. (author)

n l -> n' l' transition rates in electron and proton - Rydberg atom collision

Science.gov (United States)

Vrinceanu, Daniel

2017-04-01

Electrons and protons drive the recombination dynamics of highly excited Rydberg atoms in cold rarefied plasmas found in astrophysical conditions such as primordial recombination or star formation in H-II clouds. It has been recognized that collisions induce both energy and angular momentum transitions in Rydberg atoms, although in different proportions, depending on the initial state, temperature and the given species considered in the collision (electron or proton). Most studies focused on one collision type at a time, under the assumption that collision types are independent or their effects are not competing. The classical Monte-Carlo trajectory simulations presented in this work calculate the rates for both energy and angular momentum transfers and show their interdependence. For example, energy transfer with small angular momentum change are more efficient for target states with initial large angular momentum. The author acknowledges support received from the National Science Foundation through a Grant for the Center for Research on Complex Networks (HRD-1137732).

New Technology in Automotive Body Repair.

Science.gov (United States)

Maze, Ronald W.

1980-01-01

The use of plastic and fiberglass materials in the manufacture of automobiles has caused a revolution in the field of collision work. Changes have occurred in tools, techniques, materials, and in the training for auto body repair. The skills necessary for employment in this field are now easier and faster to acquire. (CT)

Evidence for collective phenomena from pp, p-Pb and Pb-Pb collisions at the LHC, with CMS

CERN Multimedia

CERN. Geneva

2016-01-01

The observation of a long-range, near-side, two-particle correlation (known as the ridge) has been over the past decade a key signature of the hydrodynamic evolution of the hot and strongly interacting matter produced in heavy-ion collisions. Indeed, the Quark-Gluon Plasma appears to behave as a perfect fluid and latest results from LHC experiments in Pb-Pb collisions at 2.76 and 5 TeV show a nice agreement with hydrodynamic expectations, either for inclusive charged hadrons or identified particles. The observation of the ridge in high-multiplicity pp and p-Pb collisions opened up new opportunities of exploring novel QCD dynamics in small colliding systems. While extensive studies of this long-range correlation phenomenon in p-Pb collisions have revealed its collective properties, the nature of the ridge in pp collisions remains unknown. In addition, the underlying mechanism that lies behind the ridge is still not understood, in both p-Pb and pp collisions. Latest CMS measurements of long-range particle corr...

Landing on small bodies: From the Rosetta Lander to MASCOT and beyond

Science.gov (United States)

Ulamec, Stephan; Biele, Jens; Bousquet, Pierre-W.; Gaudon, Philippe; Geurts, Koen; Ho, Tra-Mi; Krause, Christian; Lange, Caroline; Willnecker, Rainer; Witte, Lars; The Philae; Mascot Teams

2014-01-01

Recent planning for science and exploration missions has emphasized the high interest in the close investigation of small bodies in the Solar System. In particular in-situ observations of asteroids and comets play an important role in this field and will contribute substantially to our understanding of the formation and history of the Solar System. The first dedicated comet Lander is Philae, an element of ESA's Rosetta mission to comet 67/P Churyumov-Gerasimenko. Rosetta was launched in 2004. After more than 7 years of cruise (including three Earth and one Mars swing-by as well as two asteroid flybys) the spacecraft has gone into a deep space hibernation in June 2011. When approaching the target comet in early 2014, Rosetta will be re-activated. The cometary nucleus will be characterized remotely to prepare for Lander delivery, currently foreseen for November 2014. The Rosetta Lander was developed and manufactured, similar to a scientific instrument, by a consortium consisting of international partners. Project management is located at DLR in Cologne/Germany, with co-project managers at CNES (France) and ASI (Italy). The scientific lead is at the Max Planck Institute for Solar System Science (Lindau, Germany) and the Institut d'Astrophysique Spatiale (Paris). Mainly scientific institutes provided the subsystems, instruments and the complete, qualified lander system. Operations are performed in two dedicated centers, the Lander Control Center (LCC) at DLR-MUSC and the Science Operations and Navigation Center (SONC) at CNES. This concept was adopted to reduce overall cost of the project and is foreseen also to be applied for development and operations of future small bodies landers. A mission profiting from experience gained during Philae development and operations is MASCOT, a surface package for the Japanese Hayabusa 2 mission. MASCOT is a small (˜10 kg) mobile device, delivered to the surface of asteroid 1999JU3. There it will operate for about 16 h. During this

[Body composition and metabolic risk in small for gestational age children treated with growth hormone].

Science.gov (United States)

Aurensanz Clemente, Esther; Samper Villagrasa, Pilar; Ayerza Casas, Ariadna; Ruiz Frontera, Pablo; Moreno Aznar, Luis Alberto; Bueno Lozano, Gloria

2016-09-16

Small for gestational age (SGA) children are at increased risk of metabolic syndrome. Our objective is to evaluate changes in body composition produced by growth hormone (GH) treatment. A group of 28 SGA children without catch-up growth and undergoing treatment with GH was selected for evaluation. Over the course of 3 years from the beginning of the treatment with GH, the children's body composition variables (bone mineral density [BMD], fat and lean body mass proportion) were evaluated annually with dual-energy X-ray absorptiometry. A study of correlation between metabolic and body composition variables was also made. Treatment with GH produces a reduction in fat mass proportion in relation to lean body mass, decreasing from 25.94±6.09 to 22.88±5.38% (P=.034). In the abdominal regions we observe an increase in lean mass, from 1,356,91±426,71 to 2,570,96±814,36g (P=.000) and a tendency for visceral fat deposits to decrease. BMD in lumbar vertebrae improved from -1.55±0.68 to -0.90±0.79Z (P=.019). Treatment with GH produces changes in body composition, improving BMD and increasing the proportion of lean body mass with a reduction in fat mass. If these changes persisted into adulthood, they may cause a reduction in the metabolic and cardiovascular risk in this group of patients. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Adaptive inflatable structures for protecting wind turbines against ship collisions

Energy Technology Data Exchange (ETDEWEB)

Graczykowski, C.; Heinonen, J.

2006-09-15

Collisions of small ships are one of main dangers for the offshore wind turbines. Using inflatable structures surrounding the tower on the water level is a possibility of effective protection. Modelling of such structures is based on interaction between solid wall and fluid enclosed inside. Inflatable structures can be adapted to various impact schemes by adjusting initial pressure and controlling release of compressed air by opening piezo-valves. Simulations of ship collision with 2D model of wind turbine tower protected by pneumatic structure are presented in the report. Numerical analysis is performed using ABAQUS/Standard and ABAQUS/Explicit. Performed feasibility study proves that inflatable structures can protect wind turbine tower and ship against serious damages. (orig.)

Proton-Nucleus Collisions at the LHC: Scientific Opportunities and Requirements

CERN Document Server

Salgado, C A; Arleo, F; Armesto, N; Botje, M; Cacciari, M; Campbell, J; Carli, C; Cole, B; D'Enterria, D; Gelis, F; Guzey, V; Hencken, K; Jacobs, P; Jowett, J M; Klein, S R; Maltoni, F; Morsch, A; Piotrzkowski, K; Qiu, J W; Satogata, T; Sikler, F; Strikman, M; Takai, H; Vogt, R; Wessels, J P; White, S N; Wiedemann, U A; Wyslouch, B; Zhalov, M

2012-01-01

Proton-nucleus (p+A) collisions have long been recognized as a crucial component of the physics programme with nuclear beams at high energies, in particular for their reference role to interpret and understand nucleus-nucleus data as well as for their potential to elucidate the partonic structure of matter at low parton fractional momenta (small-x). Here, we summarize the main motivations that make a proton-nucleus run a decisive ingredient for a successful heavy-ion programme at the Large Hadron Collider (LHC) and we present unique scientific opportunities arising from these collisions. We also review the status of ongoing discussions about operation plans for the p+A mode at the LHC.

Foreign Body Retrieval

Medline Plus

Full Text Available ... batteries, small toys or pieces of toys and fish bones. Swallowing of magnets can cause significant problems ... bodies like toothpicks. Small esophageal foreign bodies like fish bones also may be difficult to visualize. Additional ...

Laser-assisted atom-atom collisions

International Nuclear Information System (INIS)

Roussel, F.

1984-01-01

The basic layer-assisted atom-atom collision processes are reviewed in order to get a simpler picture of the main physical facts. The processes can be separated into two groups: optical collisions where only one atom is changing state during the collision, the other acting as a spectator atom, and radiative collisions where the states of the two atoms are changing during the collision. All the processes can be interpreted in terms of photoexcitation of the quasimolecule formed during the collisional process. (author)

Evolution of the nuclide distribution and heat partition along the dissipation path in heavy ion collisions

International Nuclear Information System (INIS)

Planeta, R.

1990-04-01

We discuss several problems of nuclear physics with heavy ions. Special attention is paid to close collisions, where impact parameters are considerably smaller than the corresponding grazing values. Such collisions can lead to a formation of a compound nucleus (fusion) or to two body exit channels with a sizable loss of kinetic energy and large transfer of mass and charge between interacting nuclei (damped collisions). A short survey of experimental works done with my participation and devoted to fusion reactions is presented. This is followed by presentation of new experimental results in the field of damped collisions. The data demonstrate that the N/Z equilibration and temperature equilibration are not rapid processes. A distinct correlation between the net nucleon transfer and the heating of the acceptor nucleus is observed. Experimental data are compared with the transport model. Disagreement between model and experiment is discussed. 113 refs. (author)

Dynamical aspects of intermediate-energy nucleus-nucleus collisions. Pt. 1

International Nuclear Information System (INIS)

Cassing, W.

1987-01-01

Central collisions of heavy nuclei are investigated within the limit of selfconsistent independent single-particle motion in terms of the Wigner transform of the one-body density matrix in space and time. The energy regime considered extends from roughly 15 MeV/u to 150 MeV/u. Special attention is devoted to the relation between energy and momentum of the nucleons in the collision zone of the two nuclei. An initial average energy-momentum distribution f(k; E) is determined within the fully quantal approach which proves to be vital for our understanding of energetic particle production in the very early stage of the heavy-ion reaction. A comparison with related classical quantities shows the peculiar features of quantum dynamics for finite size fermion systems far from equilibrium. (orig.)

Hard probes in heavy ion collisions at the LHC: PDFs, shadowing and $pA$ collisions

CERN Document Server

Accardi, Alberto; Botje, M.; Brodsky, S.J.; Cole, B.; Eskola, K.J.; Fai, George I.; Frankfurt, L.; Fries, R.J.; Geist, Walter M.; Guzey, V.; Honkanen, H.; Kolhinen, V.J.; Kovchegov, Yu.V.; McDermott, M.; Morsch, A.; Qiu, Jian-wei; Salgado, C.A.; Strikman, M.; Takai, H.; Tapprogge, S.; Vogt, R.; Zhang, X.f.

2003-01-01

This manuscript is the outcome of the subgroup ``PDFs, shadowing and $pA$ collisions'' from the CERN workshop ``Hard Probes in Heavy Ion Collisions at the LHC''. In addition to the experimental parameters for $pA$ collisions at the LHC, the issues discussed are factorization in nuclear collisions, nuclear parton distributions (nPDFs), hard probes as the benchmark tests of factorization in $pA$ collisions at the LHC, and semi-hard probes as observables with potentially large nuclear effects. Also, novel QCD phenomena in $pA$ collisions at the LHC are considered. The importance of the $pA$ program at the LHC is emphasized.

Heavy quarkonium production: Nontrivial transition from pA to AA collisions

International Nuclear Information System (INIS)

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Pirner, H. J.

2011-01-01

Two novel QCD effects, double-color filtering and mutual boosting of the saturation scales in colliding nuclei, affect the transparency of the nuclei for quark dipoles in comparison with proton-nucleus collisions. The former effect increases the survival probability of the dipoles, since color filtering in one nucleus makes the other one more transparent. The second effect acts in the opposite direction and is stronger; it makes the colliding nuclei more opaque than in the case of pA collisions. As a result of parton saturation in nuclei the effective scale is shifted upward, which leads to an increase of the gluon density at small x. This in turn leads to a stronger transverse momentum broadening in AA compared with pA collisions, i.e., to an additional growth of the saturation momentum. Such a mutual boosting leads to a system of reciprocity equations, which result in a saturation scale, a few times higher in AA than in pA collisions at the energies of the large hadron collider (LHC). Since the dipole cross section is proportional to the saturation momentum squared, the nuclei become much more opaque for dipoles in AA than in pA collisions. For the same reason gluon shadowing turns out to be boosted to a larger magnitude compared with the product of the gluon shadowing factors in each of the colliding nuclei. All these effects make it more difficult to establish a baseline for anomalous J/Ψ suppression in heavy ion collisions at high energies.

Production of light fragments in hA collisions at high energies

International Nuclear Information System (INIS)

Braun, M.A.; Vechernin, V.V.

1988-12-01

Production of fast relativistic light fragments in hA collisions at high energies is considered. Direct coalescence of produced nucleons into fragments is shown to be the main mechanism for fragment production. The influence of the nuclear field is small and is not described by the well-known Butler-Pearson formulas. The coalescence coefficient strongly depends on the angle and on the behaviour of the fragment wave function at small internucleon distances. (author). 14 refs, 7 figs

Beam energy dependence of d and d ‾ production in Au+Au collisions at RHIC

Science.gov (United States)

Yu, Ning; STAR Collaboration

2017-11-01

The binding energy of light nuclei is small compared to the temperature of the system created in heavy-ion collisions. Consequently, the yields of light nuclei can be used to probe the freeze-out properties, such as correlation volume and local baryon density of the medium created in high-energy nuclear collisions. In this paper, we report the results of deuteron and anti-deuteron production in Au+Au collision at √{sNN} = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, measured by STAR at RHIC. The collision energy, centrality and transverse momentum dependence of the coalescence parameter B2 for deuteron and anti-deuteron production are discussed. We find the values of B2 for anti-deuterons are systematically lower than those for deuterons indicating the correlation volume of anti-baryon are larger than that of baryon. In addition, the values of B2 are found to vary with collision energy and show a broad minimum around √{sNN} = 20GeV, implying a change of the equation of state of the medium in these collisions.

Satellite Collision Modeling with Physics-Based Hydrocodes: Debris Generation Predictions of the Iridium-Cosmos Collision Event and Other Impact Events

International Nuclear Information System (INIS)

Springer, H.K.; Miller, W.O.; Levatin, J.L.; Pertica, A.J.; Olivier, S.S.

2010-01-01

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.

Collisions of droplets on spherical particles

Science.gov (United States)

Charalampous, Georgios; Hardalupas, Yannis

2017-10-01

Head-on collisions between droplets and spherical particles are examined for water droplets in the diameter range between 170 μm and 280 μm and spherical particles in the diameter range between 500 μm and 2000 μm. The droplet velocities range between 6 m/s and 11 m/s, while the spherical particles are fixed in space. The Weber and Ohnesorge numbers and ratio of droplet to particle diameter were between 92 deposition and splashing regimes, a regime is observed in the intermediate region, where the droplet forms a stable crown, which does not breakup but propagates along the particle surface and passes around the particle. This regime is prevalent when the droplets collide on small particles. The characteristics of the collision at the onset of rim instability are also described in terms of the location of the film on the particle surface and the orientation and length of the ejected crown. Proper orthogonal decomposition identified that the first 2 modes are enough to capture the overall morphology of the crown at the splashing threshold.

Measurement of long-range angular correlations and azimuthal anisotropies in high-multiplicity p +Au collisions at √{sNN}=200 GeV

Science.gov (United States)

Aidala, C.; Akiba, Y.; Alfred, M.; Andrieux, V.; Aoki, K.; Apadula, N.; Asano, H.; Ayuso, C.; Azmoun, B.; Babintsev, V.; Bandara, N. S.; Barish, K. N.; Bathe, S.; Bazilevsky, A.; Beaumier, M.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Blau, D. S.; Boer, M.; Bok, J. S.; Brooks, M. L.; Bryslawskyj, J.; Bumazhnov, V.; Butler, C.; Campbell, S.; Canoa Roman, V.; Cervantes, R.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Citron, Z.; Connors, M.; Cronin, N.; Csanád, M.; Csörgő, T.; Danley, T. W.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dion, A.; Dixit, D.; Do, J. H.; Drees, A.; Drees, K. A.; Dumancic, M.; Durham, J. M.; Durum, A.; Elder, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fan, W.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukuda, Y.; Gal, C.; Gallus, P.; Garg, P.; Ge, H.; Giordano, F.; Goto, Y.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; He, X.; Hemmick, T. K.; Hill, J. C.; Hill, K.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Imai, K.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ito, Y.; Ivanishchev, D.; Jacak, B. V.; Jezghani, M.; Ji, Z.; Jiang, X.; Johnson, B. M.; Jorjadze, V.; Jouan, D.; Jumper, D. S.; Kang, J. H.; Kapukchyan, D.; Karthas, S.; Kawall, D.; Kazantsev, A. V.; Khachatryan, V.; Khanzadeev, A.; Kim, C.; Kim, D. J.; Kim, E.-J.; Kim, M. H.; Kim, M.; Kincses, D.; Kistenev, E.; Klatsky, J.; Kline, P.; Koblesky, T.; Kotov, D.; Kudo, S.; Kurita, K.; Kwon, Y.; Lajoie, J. G.; Lallow, E. O.; Lebedev, A.; Lee, S.; Leitch, M. J.; Leung, Y. H.; Lewis, N. A.; Li, X.; Lim, S. H.; Liu, L. D.; Liu, M. X.; Loggins, V.-R.; Loggins, V.-R.; Lovasz, K.; Lynch, D.; Majoros, T.; Makdisi, Y. I.; Makek, M.; Malaev, M.; Manko, V. I.; Mannel, E.; Masuda, H.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Mendoza, M.; Mignerey, A. C.; Mihalik, D. E.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Mitsuka, G.; Miyasaka, S.; Mizuno, S.; Montuenga, P.; Moon, T.; Morrison, D. P.; Morrow, S. I. M.; Murakami, T.; Murata, J.; Nagai, K.; Nagashima, K.; Nagashima, T.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakano, K.; Nattrass, C.; Niida, T.; Nouicer, R.; Novák, T.; Novitzky, N.; Novotny, R.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ottino, G. J.; Ozawa, K.; Pantuev, V.; Papavassiliou, V.; Park, J. S.; Park, S.; Pate, S. F.; Patel, M.; Peng, W.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perezlara, C. E.; Perry, J.; Petti, R.; Phipps, M.; Pinkenburg, C.; Pisani, R. P.; Pun, A.; Purschke, M. L.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richford, D.; Rinn, T.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Runchey, J.; Safonov, A. S.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, K.; Sato, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seidl, R.; Sen, A.; Seto, R.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shioya, T.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Smith, K. L.; Snowball, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Syed, S.; Sziklai, J.; Takeda, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Tarnai, G.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Towell, C. L.; Towell, R. S.; Tserruya, I.; Ueda, Y.; Ujvari, B.; van Hecke, H. W.; Vazquez-Carson, S.; Velkovska, J.; Virius, M.; Vrba, V.; Vukman, N.; Wang, X. R.; Wang, Z.; Watanabe, Y.; Watanabe, Y. S.; Wong, C. P.; Woody, C. L.; Xu, C.; Xu, Q.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yamamoto, H.; Yanovich, A.; Yin, P.; Yoo, J. H.; Yoon, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zharko, S.; Zou, L.; Phenix Collaboration

2017-03-01

We present measurements of long-range angular correlations and the transverse momentum dependence of elliptic flow v2 in high-multiplicity p +Au collisions at √{s NN}=200 GeV. A comparison of these results to previous measurements in high-multiplicity d +Au and 3He+Au collisions demonstrates a relation between v2 and the initial collision eccentricity ɛ2, suggesting that the observed momentum-space azimuthal anisotropies in these small systems have a collective origin and reflect the initial geometry. Good agreement is observed between the measured v2 and hydrodynamic calculations for all systems, and an argument disfavoring theoretical explanations based on initial momentum-space domain correlations is presented. The set of measurements presented here allows us to leverage the distinct intrinsic geometry of each of these systems to distinguish between different theoretical descriptions of the long-range correlations observed in small collision systems.

ALICE event display of a Pb-Pb collision at 5.02A TeV

CERN Multimedia

Weber, Steffen Georg

2016-01-01

One of the first lead-lead collisions at the Large Hadron Collider at the top energy of 5.02 per nucleon pair in the center of mass, recorded by the ALICE detector in November 2015. In this collision of lead nuclei at a small impact parameter (central collision), 1582 positively-charged (darker tracks) and 1579 negatively-charged (lighter tracks) particles are produced; about 80 percent of them are pions. The curvature of a track in the magnetic field of ALICE (0.5 T) is inversely proportional to the momentum of the particle. The cylinder is the Time Projection Chamber of ALICE, with a diameter of 5 m and a length of 5 m, recording the charged particles in three dimensions with the equivalent of 500 million pixels.

High diversity, low disparity and small body size in plesiosaurs (Reptilia, Sauropterygia from the Triassic-Jurassic boundary.

Directory of Open Access Journals (Sweden)

Roger B J Benson

Full Text Available Invasion of the open ocean by tetrapods represents a major evolutionary transition that occurred independently in cetaceans, mosasauroids, chelonioids (sea turtles, ichthyosaurs and plesiosaurs. Plesiosaurian reptiles invaded pelagic ocean environments immediately following the Late Triassic extinctions. This diversification is recorded by three intensively-sampled European fossil faunas, spanning 20 million years (Ma. These provide an unparalleled opportunity to document changes in key macroevolutionary parameters associated with secondary adaptation to pelagic life in tetrapods. A comprehensive assessment focuses on the oldest fauna, from the Blue Lias Formation of Street, and nearby localities, in Somerset, UK (Earliest Jurassic: 200 Ma, identifying three new species representing two small-bodied rhomaleosaurids (Stratesaurus taylori gen et sp. nov.; Avalonnectes arturi gen. et sp. nov and the most basal plesiosauroid, Eoplesiosaurus antiquior gen. et sp. nov. The initial radiation of plesiosaurs was characterised by high, but short-lived, diversity of an archaic clade, Rhomaleosauridae. Representatives of this initial radiation were replaced by derived, neoplesiosaurian plesiosaurs at small-medium body sizes during a more gradual accumulation of morphological disparity. This gradualistic modality suggests that adaptive radiations within tetrapod subclades are not always characterised by the initially high levels of disparity observed in the Paleozoic origins of major metazoan body plans, or in the origin of tetrapods. High rhomaleosaurid diversity immediately following the Triassic-Jurassic boundary supports the gradual model of Late Triassic extinctions, mostly predating the boundary itself. Increase in both maximum and minimum body length early in plesiosaurian history suggests a driven evolutionary trend. However, Maximum-likelihood models suggest only passive expansion into higher body size categories.

Small gluonic spots in the nucleon: searching for signatures in data

International Nuclear Information System (INIS)

Kopeliovich, B Z; Povh, B

2004-01-01

Nuclear shadowing and colour glass condensate need sufficiently small x to provide an overlap of parton clouds in the longitudinal direction. Another condition vital for these effects is overlap of partons in impact parameters, which is not easy to fulfil for gluons, even in heavy nuclei. This is because of smallness of gluonic spots related to the weakness of diffractive gluon radiation appearing in data. The predicted weak gluon shadowing and colour glass condensate effect are now appearing in data for J/Ψ production and Cronin effect in d-Au collisions at RHIC. Smallness of gluonic spots leads to a rather small value of α' p , the slope of the Pomeron trajectory, indeed appearing in elastic photoproduction of J/Ψ. At the same time, unitarity saturation in elastic pp collisions leads to a substantial increase of α' p in good agreement with data

Tagging effects of passive integrated transponder and visual implant elastomer on the small-bodied white sands pupfish (Cyprinodon tularosa)

Science.gov (United States)

Peterson, Damon; Trantham, Randi B.; Trantham, Tulley G.; Caldwell, Colleen A.

2018-01-01

One of the greatest limiting factors of studies designed to obtain growth, movement, and survival in small-bodied fishes is the selection of a viable tag. The tag must be relatively small with respect to body size as to impart minimal sub-lethal effects on growth and mobility, as well as be retained throughout the life of the fish or duration of the study. Thus, body size of the model species becomes a major limiting factor; yet few studies have obtained empirical evidence of the minimum fish size and related tagging effects. The probability of surviving a tagging event was quantified in White Sands pupfish (Cyprinodon tularosa) across a range of sizes (19–60 mm) to address the hypothesis that body size predicts tagging survival. We compared tagging related mortality, individual taggers, growth, and tag retention in White Sands pupfish implanted with 8-mm passive integrated transponder (PIT), visual implant elastomer (VIE), and control (handled similarly, but no tag implantation) over a 75 d period. Initial body weight was a good predictor of the probability of survival in PIT- and VIE-tagged fish. As weight increased by 1 g, the fish were 4.73 times more likely to survive PIT-tag implantation compared to the control fish with an estimated suitable tagging size at 1.1 g (TL: 39.29 ± 0.41 mm). Likewise, VIE-tagged animals were 2.27 times more likely to survive a tagging event compared to the control group for every additional 1 g with an estimated size suitable for tagging of 0.9 g (TL: 36.9 ± 0.36 mm) fish. Growth rates of PIT- and VIE-tagged White Sands pupfish were similar to the control groups. This research validated two popular tagging methodologies in the White Sands pupfish, thus providing a valuable tool for characterizing vital rates in other small-bodied fishes.

ATLAS measurements of the ridge in $pp$ and $p$+Pb collisions

CERN Document Server

Tu, Xiao; The ATLAS collaboration

2017-01-01

ATLAS measurements of correlations between particle pairs in relative azimuthal angle ($\\Delta\\phi$) and pseudorapidity separation ($\\Delta\\eta$) in $pp$ collisions at $\\sqrt{s}$=5.02 and 13~TeV, and in $p$+Pb collisions at $\\sqrt{s_{\\mathrm{NN}}}$=5.02~TeV are presented. Prior measurements have shown that in $pp$ collisions with a large multiplicity of produced particles, a long-range structure (the ``ridge'') develops along $\\Delta\\eta$ at $\\Delta\\phi\\sim$0. However, due to the presence of the large away-side jet, the full $\\Delta\\phi$ dependence of the long-range correlation could not be studied. In this analysis, a template fitting procedure is implemented to determine the contributions from dijets to the correlations, using low-multiplicity events, and to extract the genuine long-range correlation. The long-range correlations are shown to be present even in events with a small multiplicity of produced particles, implying that the long-range correlations are not unique to rare high multiplicity events. Th...

Disappearance of back-to-back high-pT hadron correlations in central Au+Au collisions at sqrt[s NN ] =200 GeV.

Science.gov (United States)

Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Caines, H; Calderón de la Barca Sánchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Corral, M M; Cramer, J G; Crawford, H J; Derevschikov, A A; Didenko, L; Dietel, T; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grachov, O; Grigoriev, V; Guedon, M; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lakehal-Ayat, L; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Magestro, D; Majka, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moore, C F; Morozov, V; de Moura, M M; Munhoz, M G; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Rykov, V; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schüttauf, A; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Thompson, M; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N

2003-02-28

Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudorapidity range and full azimuth in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes previously observed in high-energy collisions. A strong back-to-back correlation exists for p+p and peripheral Au+Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.

The formation of small grains in shocks in the ISM

Science.gov (United States)

Jones, Anthony P.; Tielens, Alexander G. G. M.

1994-01-01

Carbonaceous and silicate grains swept up, and betatron accelerated, by supernova-generated shock waves in the interstellar medium are exposed to grain destructive processing. The degree of grain destruction is determined by the differential gas-grain and grain-grain velocities, which lead to sputtering of the grain surface and grain core disruption (deformation, vaporization and shattering), respectively. The threshold pressure for grain shattering in grain-grain collisions (100 k bar) is considerably lower than that for vaporization (approximately 5 M bar). Therefore, collisions between grains shatter large grains into smaller fragments (i.e., small grains and PAH's). Using a new algorithms for the destructive processes, it was possible to model the formation fo small grain fragments in grain-grain collisions in the warm phase of the interstellar medium. It was found that in one cycle through the warm medium (approximately 3 x 10(sup 6) years) of order 1-2% of the total grain mass is shattered into particles with radii of less than 50 A.

Femtoscopic analysis of baryon correlations in ultra-relativistic heavy-ion collisions registered by ALICE

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00361630

Heavy-ion collisions at ultra-relativistic energies give a unique possibility to create and to analyse the Quark-Gluon Plasma predicted by the theory of Quantum Chromodynamics. The research on the properties of such state of matter is crucial for understanding the features of the strongly interacting system. Experimental results reveal the collective behaviour of matter created in the heavy-ion collisions at ultra-relativistic energies. The existence of this effect can be verified by the measurement of the transverse mass dependence of the source size extracted using different particle species. Such characteristics can be determined using the analysis technique called femtoscopy. This method is based on the correlations of particles with small relative momenta which originate from the effects of Quantum Statistics as well as the strong and Coulomb Final State Interactions. A recent analysis of the particle production at the highest available collision energies of heavy-ion collisions reveals the puzzling res...

Multiplicity distributions in. pi. /sup +/d and pd collisions at 100 GeV/c

Energy Technology Data Exchange (ETDEWEB)

Dado, S; Engler, A; Keyes, G; Kraemer, R W; Yekutieli, G [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA); Binkley, M; Lys, J E.A.; Murphy, C T [Fermi National Accelerator Lab., Batavia, Ill. (USA); Engelmann, R; Hanlon, J

1976-02-02

From an exposure of the 30-inch deuterium bubble chamber at Fermilab 7600 events with three or more charged prongs are examined. Multiplicity distributions for ..pi../sup +/n, pn, ..pi../sup +/d and pd collisions are presented and are in general agreement with those expected based on knowledge of ..pi../sup -/p, ..pi../sup +/p, and pp collisions at the same energy. It is found that double scattering in the deuteron, which occurs in about 14% of events, causes at most small effects on the multiplicity distributions.

Effect of prewarming on the body temperature of small dogs undergoing inhalation anesthesia.

Science.gov (United States)

Rigotti, Clara F; Jolliffe, Colette T; Leece, Elizabeth A

2015-10-01

To investigate whether prewarming affects body temperature of small dogs (weighing dogs weighing temperature was recorded. Before IM administration of buprenorphine hydrochloride and acepromazine maleate, dogs were randomly assigned to be placed in a pediatric incubator at 33°C (91.4°F) for approximately 30 to 60 minutes (prewarming group) or to receive no prewarming (control group); subsequently, dogs underwent inhalation anesthesia with isoflurane in oxygen. Rectal, esophageal, and ambient temperatures were measured every 5 minutes from induction of anesthesia (IOA) for > 1 hour by an observer who was unaware of treatment. If a dog became hypothermic (esophageal temperature dogs, anesthesia, temperatures, hypothermia, and study withdrawal were compared between groups. 1 dog was excluded from the prewarming group after becoming excessively excited in the incubator. Between groups, age, weight, body condition score, degree of preanesthesia sedation, interval from sedation to IOA, duration of anesthesia, baseline rectal temperature, rectal temperatures immediately prior to IOA, esophageal temperature following IOA, ambient temperature during the first 70 minutes of anesthesia, esophageal or rectal temperature during the first 90 minutes of anesthesia, and incidence of hypothermia and study withdrawal (5 dogs/group) did not differ significantly. Prewarming in an incubator prior to IOA failed to improve or maintain body temperature of dogs weighing < 10 kg during inhalation anesthesia.

Studies of nucleus-nucleus collisions with a schematic liquid-drop model and one-body dissipation

Energy Technology Data Exchange (ETDEWEB)

Donangelo, R; Canto, L F

1986-03-24

The inclusion of an asymmetry friction term into the dissipation function of the schematic model of nuclear collisions due to WJ Swiatecki is found to change some of the earlier predictions of the model, in particular the scaling relation for the extra-push and extra-extra-push energies and the existence of a cliff phenomenon. (orig.).

The Small Acceptance Vertex Detector of NA61/SHINE

Directory of Open Access Journals (Sweden)

Deveaux M.

2018-01-01

Full Text Available Charmonium production in heavy ion collisions is considered as an important diagnostic probe for studying the phase diagram of strongly interacting matter for potential phase transitions. The interpretation of existing data from the CERN SPS is hampered by a lack of knowledge on the properties of open charm particle production in the fireball. Moreover, open charm production in heavy ion collisions by itself is poorly understood. To overcome this obstacle, the NA61/SHINE was equipped with a Small Acceptance Vertex Detector (SAVD, which is predicted to make the experiment sensitive to open charm mesons produced in A-A collisions at the SPS top energy. This paper will introduce the concept and the hardware of the SAVD. Moreover, first running experience as obtained in a commissioning run with a 150 AGeV/c Pb+Pb collision system will be reported.

Basins in ARC-continental collisions

Science.gov (United States)

Draut, Amy E.; Clift, Peter D.; Busby, Cathy; Azor, Antonio

2012-01-01

Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

Coorbital Collision as the Energy Source for Enceladus' Plumes

Science.gov (United States)

Peale, Stanton J.; Greenberg, R.

2009-09-01

A collision of a coorbiting satellite with Enceladus is proposed as the source of energy to power the observed plumes emanating from the south pole of the satellite. A coorbital would have impacted at a velocity only slightly above the escape velocity of Enceladus, which would likely be necessary to keep the collision gentle enough not to disrupt the old cratered terrain nearby. If the mass were 1% of Enceladus', the energy deposited can sustain the plumes for approximately 80,000 to 200,000 years at the estimated observed power of 6 to 15 GW, so the impact would have been quite recent. The collision at an arbitrary point would leave Enceladus with non-synchronous, non-principal-axis rotation and a significant obliquity. After subsuming the impactor's volume, the region around the impact point will have expanded in a manner consistent with the observed tectonic pattern. The ring-like expansion implied by the radial cracks suggests that the new principal axis of maximum moment of inertia could have passed through the impact point. Internal dissipation from precession of the spin axis about the axis of maximum moment of inertia in the body frame of reference and from tides raised on Enceladus cause the axes of spin and of maximum moment to converge as the spin is brought to a zero obliquity and synchronous rotation on a time scale that is extremely short compared to the lifetime of the plumes. Hence, the region of collision, which is hot, ends up at one of the poles where we find the plumes.

Amino Acid Chemistry as a Link Between Small Solar System Bodies and Carbonaceous Chondrites

Science.gov (United States)

Glavin, Daniel P.; Ehrenfreund, Pascale; Botta, Oliver; Cooper, George; Bada, Jeffrey L.

2000-01-01

Establishing chemical links between meteorites and small solar system bodies, such as comets and asteroids, provides a tool for investigating the processes that occurred during the formation of the solar system. Carbonaceous meteorites are of particular interest, since they may have seeded the early Earth with a variety of prebiotic organic compounds including amino acids, purines and pyrimidines, which are thought to be necessary for the origin of life. Here we report the results of high-performance liquid chromatography (HPLC) based amino acid analyses of the acid-hydrolyzed hot water extracts from pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna and the CM meteorites Murchison and Murray. We found that the CI meteorites Orgueil and Ivuna contained high abundances of beta-alanine and glycine, while only traces of other amino acids like alanine, alpha-amino-n-butryic acid (ABA) and alpha-aminoisobutyric acid (AIB) were detected in these meteorites. Carbon isotopic measurements of beta-alanine and glycine in Orgueil by gas chromatography combustion-isotope ratio mass spectrometry clearly indicate an extraterrestrial origin of these amino acids. The amino acid composition of Orgueil and Ivuna was strikingly different from the CM chondrites Murchison and Murray. The most notable difference was the high relative abundance of B-alanine in Orgueil and Ivuna compared to Murchison and Murray. Furthermore, AIB, which is one of the most abundant amino acids found in Murchison and Murray, was present in only trace amounts in Orgueil and Ivuna. Our amino acid data strongly suggest that the CI meteorites Orgueil and Ivuna came from a different type of parent body than the CM meteorites Murchison and Murray, possibly from an extinct comet. It is generally thought that carbonaceous meteorites are fragments of larger asteroidal bodies delivered via near Earth objects (NEO). Orbital and dynamic studies suggest that both fragments of main belt asteroids

Baryon-antibaryon dynamics in relativistic heavy-ion collisions

Science.gov (United States)

Seifert, E.; Cassing, W.

2018-04-01

The dynamics of baryon-antibaryon annihilation and reproduction (B B ¯↔3 M ) is studied within the Parton-Hadron-String Dynamics (PHSD) transport approach for Pb+Pb and Au+Au collisions as a function of centrality from lower Super Proton Synchrotron (SPS) up to Large Hadron Collider (LHC) energies on the basis of the quark rearrangement model. At Relativistic Heavy-Ion Collider (RHIC) energies we find a small net reduction of baryon-antibaryon (B B ¯ ) pairs while for the LHC energy of √{sN N}=2.76 TeV a small net enhancement is found relative to calculations without annihilation (and reproduction) channels. Accordingly, the sizable difference between data and statistical calculations in Pb+Pb collisions at √{sN N}=2.76 TeV for proton and antiproton yields [ALICE Collaboration, B. Abelev et al., Phys. Rev. C 88, 044910 (2013), 10.1103/PhysRevC.88.044910], where a deviation of 2.7 σ was claimed by the ALICE Collaboration, should not be attributed to a net antiproton annihilation. This is in line with the observation that no substantial deviation between the data and statistical hadronization model (SHM) calculations is seen for antihyperons, since according to the PHSD analysis the antihyperons should be modified by the same amount as antiprotons. As the PHSD results for particle ratios are in line with the ALICE data (within error bars) this might point towards a deviation from statistical equilibrium in the hadronization (at least for protons and antiprotons). Furthermore, we find that the B B ¯↔3 M reactions are more effective at lower SPS energies where a net suppression for antiprotons and antihyperons up to a factor of 2-2.5 can be extracted from the PHSD calculations for central Au+Au collisions.

Sequential Probability Ratio Test for Spacecraft Collision Avoidance Maneuver Decisions

Science.gov (United States)

Carpenter, J. Russell; Markley, F. Landis

2013-01-01

A document discusses sequential probability ratio tests that explicitly allow decision-makers to incorporate false alarm and missed detection risks, and are potentially less sensitive to modeling errors than a procedure that relies solely on a probability of collision threshold. Recent work on constrained Kalman filtering has suggested an approach to formulating such a test for collision avoidance maneuver decisions: a filter bank with two norm-inequality-constrained epoch-state extended Kalman filters. One filter models the null hypotheses that the miss distance is inside the combined hard body radius at the predicted time of closest approach, and one filter models the alternative hypothesis. The epoch-state filter developed for this method explicitly accounts for any process noise present in the system. The method appears to work well using a realistic example based on an upcoming, highly elliptical orbit formation flying mission.

LightForce: An Update on Orbital Collision Avoidance Using Photon Pressure

Science.gov (United States)

Stupl, Jan; Mason, James; De Vries, Willem; Smith, Craig; Levit, Creon; Marshall, William; Salas, Alberto Guillen; Pertica, Alexander; Olivier, Scot; Ting, Wang

2012-01-01

We present an update on our research on collision avoidance using photon-pressure induced by ground-based lasers. In the past, we have shown the general feasibility of employing small orbit perturbations, induced by photon pressure from ground-based laser illumination, for collision avoidance in space. Possible applications would be protecting space assets from impacts with debris and stabilizing the orbital debris environment. Focusing on collision avoidance rather than de-orbit, the scheme avoids some of the security and liability implications of active debris removal, and requires less sophisticated hardware than laser ablation. In earlier research we concluded that one ground based system consisting of a 10 kW class laser, directed by a 1.5 m telescope with adaptive optics, could avoid a significant fraction of debris-debris collisions in low Earth orbit. This paper describes our recent efforts, which include refining our original analysis, employing higher fidelity simulations and performing experimental tracking tests. We investigate the efficacy of one or more laser ground stations for debris-debris collision avoidance and satellite protection using simulations to investigate multiple case studies. The approach includes modeling of laser beam propagation through the atmosphere, the debris environment (including actual trajectories and physical parameters), laser facility operations, and simulations of the resulting photon pressure. We also present the results of experimental laser debris tracking tests. These tests track potential targets of a first technical demonstration and quantify the achievable tracking performance.

Central collisions of heavy ions

International Nuclear Information System (INIS)

Fung, Sun-yiu.

1991-10-01

This report describes the activities of the Heavy Ion Physics Group at the University of California, Riverside from October 1, 1990 to September 30, 1991. During this period, our program focuses on particle production at AGS energies, and correlation studies at the Bevalac in nucleus central collisions. We participated in the preparation of letters of intent for two RHIC experiments -- the OASIS proposal and the Di-Muon proposal -- and worked on two RHIC R ampersand D efforts -- a silicon strip detector project and a muon-identifier project. A small fraction of time was also devoted to physics programs outside the realm of heavy ion reactions by several individuals

Motion of small bodies in classical field theory

International Nuclear Information System (INIS)

Gralla, Samuel E.

2010-01-01

I show how prior work with R. Wald on geodesic motion in general relativity can be generalized to classical field theories of a metric and other tensor fields on four-dimensional spacetime that (1) are second-order and (2) follow from a diffeomorphism-covariant Lagrangian. The approach is to consider a one-parameter-family of solutions to the field equations satisfying certain assumptions designed to reflect the existence of a body whose size, mass, and various charges are simultaneously scaled to zero. (That such solutions exist places a further restriction on the class of theories to which our results apply.) Assumptions are made only on the spacetime region outside of the body, so that the results apply independent of the body's composition (and, e.g., black holes are allowed). The worldline 'left behind' by the shrinking, disappearing body is interpreted as its lowest-order motion. An equation for this worldline follows from the 'Bianchi identity' for the theory, without use of any properties of the field equations beyond their being second-order. The form of the force law for a theory therefore depends only on the ranks of its various tensor fields; the detailed properties of the field equations are relevant only for determining the charges for a particular body (which are the ''monopoles'' of its exterior fields in a suitable limiting sense). I explicitly derive the force law (and mass-evolution law) in the case of scalar and vector fields, and give the recipe in the higher-rank case. Note that the vector force law is quite complicated, simplifying to the Lorentz force law only in the presence of the Maxwell gauge symmetry. Example applications of the results are the motion of 'chameleon' bodies beyond the Newtonian limit, and the motion of bodies in (classical) non-Abelian gauge theory. I also make some comments on the role that scaling plays in the appearance of universality in the motion of bodies.

Theoretical study of alignment and orientation of n = 2 levels in Li++He collision

International Nuclear Information System (INIS)

Courbin, C.; Sidis, V.

1986-01-01

The determination of alignment and orientation parameters from differential cross section measurements involving the photon-particle coincidence technique prompts theory to investigate a wide variety of electronic transitions both at small and large distances of approach between the collision partners. A theoretical model is presented with a view to explaining alignment and orientation phenomena related to Li + +He*(2 1 P) excitation and Li*(2 2 P)+He + charge exchange excitation in the prototype Li + +He collision. The corresponding discussion is illustrated using a recent ab initio study by the authors [fr

On impact mechanics in ship collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Zhang, Shengming

1998-01-01

The purpose of this paper is to present analytical, closed-form expressions for the energy released for crushing and the impact impulse during ship collisions. Ship–ship collisions, ship collisions with rigid walls and ship collisions with flexible offshore structures are considered. The derived ...

On Impact Mechanics in Ship Collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Zhang, Shengming

1998-01-01

The purpose of this paper is to present analytical, closed-form expressions for the energy released for crushing and the impact impulse during ship collisions. Ship-ship collisions, ship collisions with rigid walls and ship collisions with flexible offshore structures are considered. The derived ...

Rotation-induced YORP break-up of small bodies to produce post-main-sequence debris

Science.gov (United States)

Veras, D.; Jacobson, S. A.; Gänsicke, B. T.

2017-09-01

We hypothesize that the in situ break-up of small bodies such as asteroids spun to fission during the giant branch phases of stellar evolution provides an important contribution to the debris orbiting and ultimately polluting white dwarfs. The YORP (Yarkovsky-O'Keefe-Radviesvki-Paddock) effect, which arises from radiation pressure, accelerates the spin rate of asymmetric asteroids, which can eventually shear themselves apart. This pressure is maintained and enhanced around dying stars because the outward push of an asteroid due to stellar mass loss is insignificant compared to the resulting stellar luminosity increase. Consequently, giant star radiation will destroy nearly all bodies with radii in the range 100 m-10 km that survive their parent star's main-sequence lifetime within a distance of about 7 au; smaller bodies are spun apart to their strongest, competent components. This estimate is conservative and would increase for highly asymmetric shapes or incorporation of the inward drag due to giant star stellar wind. The resulting debris field, which could extend to thousands of au, may be perturbed by remnant planetary systems to reproduce the observed dusty and gaseous discs which accompany polluted white dwarfs.

Gravitational waves from cosmic bubble collisions

International Nuclear Information System (INIS)

Kim, Dong-Hoon; Lee, Bum-Hoon; Lee, Wonwoo; Yang, Jongmann; Yeom, Dong-han

2015-01-01

Cosmic bubbles are nucleated through the quantum tunneling process. After nucleation they would expand and undergo collisions with each other. In this paper, we focus in particular on collisions of two equal-sized bubbles and compute gravitational waves emitted from the collisions. First, we study the mechanism of the collisions by means of a real scalar field and its quartic potential. Then, using this model, we compute gravitational waves from the collisions in a straightforward manner. In the quadrupole approximation, time-domain gravitational waveforms are directly obtained by integrating the energy-momentum tensors over the volume of the wave sources, where the energy-momentum tensors are expressed in terms of the scalar field, the local geometry and the potential. We present gravitational waveforms emitted during (i) the initial-to-intermediate stage of strong collisions and (ii) the final stage of weak collisions: the former is obtained numerically, in full General Relativity and the latter analytically, in the flat spacetime approximation. We gain qualitative insights into the time-domain gravitational waveforms from bubble collisions: during (i), the waveforms show the non-linearity of the collisions, characterized by a modulating frequency and cusp-like bumps, whereas during (ii), the waveforms exhibit the linearity of the collisions, featured by smooth monochromatic oscillations. (orig.)

Soft electromagnetic bremsstrahlung in inelastic hadronic collisions at high and intermediate energies

International Nuclear Information System (INIS)

Rueckl, R.

1978-01-01

Electromagnetic bremsstrahlung in hadronic collisions was studied extensively at low and intermediate energies. It was found that the infrared divergent term of the cross section describes the data well up to surprisingly large photon energies. Using essentially the same soft photon approximation, production of low mass-low energy electron pairs via internal conversion of soft virtual bremsstrahlung accompanying the production of charged hadrons in hadron-hadron collisions at very high and intermediate energies. The resulting electron yields explain, at least in part, the direct electrons with small transverse momenta seen at the ISR, and are in no contradiction to the rates observed at LAMPF

Fragmentation of CO{sub 2} into C{sup +} + O{sup +} + O, in collisions with protons

Energy Technology Data Exchange (ETDEWEB)

Moretto-Capelle, P. [Laboratoire CAR-IRSAMC, UMR 5589 CNRS-Universite Paul Sabatier, 118 rue de Narbonne, 31062 Toulouse Cedex (France). E-mail: pmc at yosemite.ups-tlse.fr; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Laboratoire CAR-IRSAMC, UMR 5589 CNRS-Universite Paul Sabatier, 118 rue de Narbonne, 31062 Toulouse Cedex (France)

2000-08-14

The fragmentation of CO{sub 2} has been investigated in 25 keV H{sup +} + CO{sub 2} collisions using an electron-ion-ion triple coincidence technique. In this letter we focus on the three-body fragmentation into the C{sup +} + O{sup +} + O final state. A comparison between the measured correlation of C{sup +},O{sup +} and O momenta and simple kinematic models allows us to demonstrate that in the present case, a rather unexpected two-step process with formation of a CO{sup 2+} ion as an intermediate state occurs. This result is at variance with the conclusions of other authors achieved in collisions of photons and electrons with the dioxide molecule. Kinetic energy release distributions in the two steps of the dissociation process are also deduced from experiment; the distributions found for the fragmentation of CO{sup 2+} into C{sup +} + O{sup +} are found to be very similar to those measured by other authors in collisions of various particles (photons, multi-charged ions) with CO molecules at high enough collision energy. (author). Letter-to-the-editor.

On the quantum Landau collision operator and electron collisions in dense plasmas

Energy Technology Data Exchange (ETDEWEB)

Daligault, Jérôme, E-mail: daligaul@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2016-03-15

The quantum Landau collision operator, which extends the widely used Landau/Fokker-Planck collision operator to include quantum statistical effects, is discussed. The quantum extension can serve as a reference model for including electron collisions in non-equilibrium dense plasmas, in which the quantum nature of electrons cannot be neglected. In this paper, the properties of the Landau collision operator that have been useful in traditional plasma kinetic theory and plasma transport theory are extended to the quantum case. We outline basic properties in connection with the conservation laws, the H-theorem, and the global and local equilibrium distributions. We discuss the Fokker-Planck form of the operator in terms of three potentials that extend the usual two Rosenbluth potentials. We establish practical closed-form expressions for these potentials under local thermal equilibrium conditions in terms of Fermi-Dirac and Bose-Einstein integrals. We study the properties of linearized quantum Landau operator, and extend two popular approximations used in plasma physics to include collisions in kinetic simulations. We apply the quantum Landau operator to the classic test-particle problem to illustrate the physical effects embodied in the quantum extension. We present useful closed-form expressions for the electron-ion momentum and energy transfer rates. Throughout the paper, similarities and differences between the quantum and classical Landau collision operators are emphasized.

On the quantum Landau collision operator and electron collisions in dense plasmas

Science.gov (United States)

Daligault, Jérôme

2016-03-01

The quantum Landau collision operator, which extends the widely used Landau/Fokker-Planck collision operator to include quantum statistical effects, is discussed. The quantum extension can serve as a reference model for including electron collisions in non-equilibrium dense plasmas, in which the quantum nature of electrons cannot be neglected. In this paper, the properties of the Landau collision operator that have been useful in traditional plasma kinetic theory and plasma transport theory are extended to the quantum case. We outline basic properties in connection with the conservation laws, the H-theorem, and the global and local equilibrium distributions. We discuss the Fokker-Planck form of the operator in terms of three potentials that extend the usual two Rosenbluth potentials. We establish practical closed-form expressions for these potentials under local thermal equilibrium conditions in terms of Fermi-Dirac and Bose-Einstein integrals. We study the properties of linearized quantum Landau operator, and extend two popular approximations used in plasma physics to include collisions in kinetic simulations. We apply the quantum Landau operator to the classic test-particle problem to illustrate the physical effects embodied in the quantum extension. We present useful closed-form expressions for the electron-ion momentum and energy transfer rates. Throughout the paper, similarities and differences between the quantum and classical Landau collision operators are emphasized.

Inclusion of the diffuseness in the schematic model of heavy ion collisions

International Nuclear Information System (INIS)

Marta, H.D.

1989-01-01

The schematic model of central heavy ion collisions developed by Swiatecki includes the Coulomb and surface contributions to the potential energy of the system and one-body dissipation. This model is extended by considering the diffuseness of the nuclear surface; this has the implication that we must consider the proximity forces in the dynamics of the collisions. For the sake of simplicity we work with symmetrical systems. The results of the model studied are compared with experimental data and with other theoretical calculations. We conclude that the detailed consideration of the diffuseness of the nuclear surfaces does not substantially change the results of the schematic model for sharp surfaces in which the diffuseness is considered only through the parameters. (author) [pt

Electron-molecule collisions

CERN Document Server

Takayanagi, Kazuo

1984-01-01

Scattering phenomena play an important role in modern physics. Many significant discoveries have been made through collision experiments. Amongst diverse kinds of collision systems, this book sheds light on the collision of an electron with a molecule. The electron-molecule collision provides a basic scattering problem. It is scattering by a nonspherical, multicentered composite particle with its centers having degrees of freedom of motion. The molecule can even disintegrate, Le., dissociate or ionize into fragments, some or all of which may also be molecules. Although it is a difficult problem, the recent theoretical, experimental, and computational progress has been so significant as to warrant publication of a book that specializes in this field. The progress owes partly to technical develop­ ments in measurements and computations. No less important has been the great and continuing stimulus from such fields of application as astrophysics, the physics of the earth's upper atmosphere, laser physics, radiat...

A flow paradigm in heavy-ion collisions

Science.gov (United States)

Yan, Li

2018-04-01

The success of hydrodynamics in high energy heavy-ion collisions leads to a flow paradigm, to understand the observed features of harmonic flow in terms of the medium collective expansion with respect to initial state geometrical properties. In this review, we present some essential ingredients in the flow paradigm, including the hydrodynamic modeling, the characterization of initial state geometry and the medium response relations. The extension of the flow paradigm to small colliding systems is also discussed. Supported by Natural Sciences and Engineering Research Council of Canada

Role of Surface Chemistry in Grain Adhesion and Dissipation during Collisions of Silica Nanograins

Energy Technology Data Exchange (ETDEWEB)

Quadery, Abrar H.; Tucker, William C.; Dove, Adrienne R.; Schelling, Patrick K. [Department of Physics, University of Central Florida, Orlando, FL 32816-2385 (United States); Doan, Baochi D., E-mail: patrick.schelling@ucf.edu [Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816-2385 (United States)

2017-08-01

The accretion of dust grains to form larger objects, including planetesimals, is a central problem in planetary science. It is generally thought that weak van der Waals interactions play a role in accretion at small scales where gravitational attraction is negligible. However, it is likely that in many instances, chemical reactions also play an important role, and the particular chemical environment on the surface could determine the outcomes of dust grain collisions. Using atomic-scale simulations of collisional aggregation of nanometer-sized silica (SiO{sub 2}) grains, we demonstrate that surface hydroxylation can act to weaken adhesive forces and reduce the ability of mineral grains to dissipate kinetic energy during collisions. The results suggest that surface passivation of dangling bonds, which generally is quite complete in an Earth environment, should tend to render mineral grains less likely to adhere during collisions. It is shown that during collisions, interactions scale with interparticle distance in a manner consistent with the formation of strong chemical bonds. Finally, it is demonstrated that in the case of collisions of nanometer-scale grains with no angular momentum, adhesion can occur even for relative velocities of several kilometers per second. These results have significant implications for early planet formation processes, potentially expanding the range of collision velocities over which larger dust grains can form.

Small cell type neuroendocrine carcinoma colliding with squamous cell carcinoma at esophagus

Science.gov (United States)

Yang, Luoluo; Sun, Xun; Zou, Yabin; Meng, Xiangwei

2014-01-01

Collision tumor is an extremely rare tumor which defined as the concrescence of two distinct primaries neoplasms. We report here a case of collision tumor at lower third esophagus composed of small cell type neuroendocrine carcinoma (NEC), which is an very rare, highly aggressive and poorly prognostic carcinoma and squamous cell carcinoma (SqCC). In our case, pathologically, the small cell carcinoma display the characteristic of small, round, ovoid or spindle-shaped tumor cells with scant cytoplasm, which colliding with a moderately differentiated squamous cell carcinoma. Immunohistochemical staining demonstrated positive activities for CD56, synaptophysin, 34βE12, CK 5/6, ki-67 (70%-80%), but negative for CD99, chromogranin A, and TTF-1. Accurate diagnosis was made base on these findings. PMID:24817981

Probing Efimov discrete scaling in an atom-molecule collision

Science.gov (United States)

Shalchi, M. A.; Yamashita, M. T.; Hadizadeh, M. R.; Garrido, E.; Tomio, Lauro; Frederico, T.

2018-01-01

The discrete Efimov scaling behavior, well known in the low-energy spectrum of three-body bound systems for large scattering lengths (unitary limit), is identified in the energy dependence of an atom-molecule elastic cross section in mass-imbalanced systems. That happens in the collision of a heavy atom with mass mH with a weakly bound dimer formed by the heavy atom and a lighter one with mass mL≪mH . Approaching the heavy-light unitary limit, the s -wave elastic cross section σ will present a sequence of zeros or minima at collision energies following closely the Efimov geometrical law. Our results, obtained with Faddeev calculations and supplemented by a Born-Oppenheimer analysis, open a perspective to detecting the discrete scaling behavior from low-energy scattering data, which is timely in view of the ongoing experiments with ultracold binary mixtures having strong mass asymmetries, such as lithium and cesium or lithium and ytterbium.

Oblique collisions of baseballs and softballs with a bat

Science.gov (United States)

Kensrud, Jeffrey R.; Nathan, Alan M.; Smith, Lloyd V.

2017-07-01

Experiments are done by colliding a swinging bat with a stationary baseball or softball. Each collision was recorded with high-speed cameras from which the post-impact speed, launch angle, and spin of the ball could be determined. Initial bat speeds were in the range 63-88 mph, producing launch angles in the range 0°-30° and spins in the range 0-3,500 rpm. The results are analyzed in the context of a ball-bat collision model, and the parameters of that model are determined. For both baseballs and softballs, the data are consistent with a mechanism whereby the ball grips the surface of the bat, stretching the ball in the transverse direction and resulting in a spin that was up to 40% greater than would be obtained by rolling contact of rigid bodies. Using a lumped parameter contact model, baseballs are shown to be less compliant tangentially than softballs. Implications of our results for batted balls in game situations are presented.

Strangeness in nuclear collisions

International Nuclear Information System (INIS)

Gazdzicki, M.; Roehrich, D.

1996-01-01

Data on the mean multiplicity of strange hadrons produced in minimum bias proton-proton and central nucleus-nucleus collisions at momenta between 2.8 and 400 GeV/c per nucleon have been compiled. The multiplicities for nucleon-nucleon interactions were constructed. The ratios of strange particle multiplicity to participant nucleon as well as to pion multiplicity are larger for central nucleus-nucleus collisions than for nucleon-nucleon interactions at all studied energies. The data at AGS energies suggest that the latter ratio saturates with increasing masses of the colliding nuclei. The strangeness to pion multiplicity ratio observed in nucleon-nucleon interactions increases with collision energy in the whole energy range studied. A qualitatively different behaviour is observed for central nucleus-nucleus collisions: the ratio rapidly increases when going from Dubna to AGS energies and changes little between AGS and SPS energies. This change in the behaviour can be related to the increase in the entropy production observed in central nucleus-nucleus collisions at the same energy range. The results are interpreted within a statistical approach. They are consistent with the hypothesis that the quark gluon plasma is created at SPS energies, the critical collision energy being between AGS and SPS energies. (orig.)

Collision-produced atomic states

International Nuclear Information System (INIS)

Andersen, N.; Copenhagen Univ.

1988-01-01

The last 10-15 years have witnessed the development of a new, powerful class of experimental techniques for atomic collision studies, allowing partial or complete determination of the state of the atoms after a collision event, i.e. the full set of quantum-mechanical scattering amplitudes or - more generally - the density matrix describing the system. Evidently, such studies, involving determination of alignment and orientation parameters, provide much more severe tests of state-of-the-art scattering theories than do total or differential cross section measurements which depend on diagonal elements of the density matrix. The off-diagonal elements give us detailed information about the shape and dynamics of the atomic states. Therefore, close studies of collision-produced atomic states are currently leading to deeper insights into the fundamental physical mechanisms governing the dynamics of atomic collision events. The first part of the lectures deals with the language used to describe atomic states, while the second part presents a selection of recent results for model systems which display fundamental aspects of the collision physics in particularly instructive ways. I shall here restrict myself to atom-atom collisions. The discussion will be focused on states decaying by photon emission though most of the ideas can be easily modified to include electron emission as well. (orig./AH)

Time dependent mean field approximation to the many-body S-matrix

International Nuclear Information System (INIS)

Alhassid, Y.; Koonin, S.E.

1980-01-01

Time-dependent Hartree-Fock (TDHF) calculations are a good description of some inclusive properties of deep inelastic heavy-ion collisions. The first steps toward a mean-field theory that approximates specific elements of the many-body S matrix are presented. A many-body system with pairwise interactions excited by an external, time-dependent one-body field is considered. The methods are used to solve the forced Lipkin model. The moduli of elastic and excitation amplitudes are plotted. 3 figures

Overpopulation of Omega; in pp collisions: a way to distinguish statistical hadronization from string dynamics.

Science.gov (United States)

Bleicher, M; Liu, F M; Keränen, A; Aichelin, J; Bass, S A; Becattini, F; Redlich, K; Werner, K

2002-05-20

The Omega/Omega ratio originating from string decays is predicted to be larger than unity in proton-proton interactions at SPS energies ( E(lab) = 160 GeV). The antiomega dominance increases with decreasing beam energy. This surprising behavior is caused by the combinatorics of quark-antiquark production in small and low-mass strings. Since this behavior is not found in a statistical description of hadron production in proton-proton collisions, it may serve as a key observable to probe the hadronization mechanism in such collisions.

Overpopulation of Ω in pp collisions: A way to distinguish statistical hadronization from string dynamics

International Nuclear Information System (INIS)

Bleicher, M.; Liu, F. M.; Aichelin, J.; Werner, K.; Keraenen, A.; Bass, S. A.; Becattini, F.; Redlich, K.

2002-01-01

The Ω/Ω ratio originating from string decays is predicted to be larger than unity in proton-proton interactions at SPS energies (E lab =160 GeV ). The antiomega dominance increases with decreasing beam energy. This surprising behavior is caused by the combinatorics of quark-antiquark production in small and low-mass strings. Since this behavior is not found in a statistical description of hadron production in proton-proton collisions, it may serve as a key observable to probe the hadronization mechanism in such collisions

Measurement of the energy spectra relative to neutrons produced at very small angle in $\\mathrm{\\sqrt{s} = 13 ~ TeV}$ proton-proton collisions using the LHCf Arm2 detector

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00533910

In the last years, several ground-based experiments have measured flux and composition of ultra high energy cosmic rays - i.e. cosmic rays having energies above $10^{18} ~ eV$ - up to the GZK cutoff region. Nevertheless, these analyses suffer of large uncertainties due to the fact that they must rely on hadronic interaction models, that exhibit very different behavior in the forward region due to the lack of high energy calibration data. To provide measurements that can be useful to tune these models is exactly the main aim of the LHC-forward (LHCf) experiment. Thanks to two small sampling calorimeter, Arm1 and Arm2, installed at $\\pm 140 ~ m$ from LHC IP1, LHCf can detect neutral particles produced in the very forward region ($\\eta > 8.4$) by proton-proton and proton-ion high energy collisions (proton-proton interaction at $\\sqrt{s} = 14 ~ TeV$ is equivalent to the collision of a $10^{17} ~ eV$ proton with a proton at rest, hence it is possible to perform measurements at an energy close to the typical one of...

Properties of the systems created in p-p and p-Pb collisions in ALICE at LHC

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00506861; Ortiz Velasquez, Antonio

It has been established that ultra-relativistic heavy-ion collisions produce a hot and dense QCD system which behaves like a perfect fluid. Albeit, the system is not the theoretical predicted Quark Gluon Plasma, its study results important to understand the cosmic evolution of our Universe. As well as specific aspects of QCD in the non-perturbative sector. For three decades, minimum-bias proton-proton collisions were used as the baseline in order to extract the novel properties of the hot and dense systems. Surprisingly, the analysis of pp collisions as a function of the event multiplicity revealed new phenomena: collective-like behavior. For the heavy-ion community it is crucial to understand the origin of the similarities among the systems created in pp, p-A and A-A collisions. In this thesis a study of small systems (pp and p-A collisions) as a function of the jet content and multiplicity was done, multi-partonic interactions and color reconnection have received special attention because they can produce r...

Study of J/ψ production dependence with the charged particle multiplicity in p-Pb collisions at √(s_N_N) = 5.02 TeV and pp collisions at √(s)= 8 TeV with the ALICE experiment at LHC

International Nuclear Information System (INIS)

Martin Blanco, J.

2015-01-01

A suppression (relative to the measurement in pp collisions at the same energy) of the J/ψ production was found in Pb-Pb collisions at √(s_N_N) = 2.76 TeV, providing further evidence of the formation of a deconfined medium in ultra-relativistic heavy-ion collisions, the so-called Quark-Gluon Plasma. In addition, p-Pb collisions at √(s_N_N) = 5.02 TeV have been studied at the LHC to measure cold nuclear matter effects (e.g. gluon shadowing, energy loss, nuclear absorption). Understanding p-Pb collisions will help to disentangle hot and cold nuclear matter effects in Pb-Pb collisions. Surprisingly, some observables in p-Pb collisions behave as in heavy-ion collisions where it is understood as a result of a collective expansion of the medium. This thesis analyses inclusive J/ψ production in p-Pb and pp collisions with the ALICE muon spectrometer. The J/ψ production rate, and its mean transverse momentum, have been measured at forward and backward rapidities as a function of the charged particle multiplicity. Measurements of particle production as a function of the event multiplicity in small size systems provide a way to sign the presence of collective final state effects like those observed in Pb-Pb collisions. In p-Pb collisions, the observed increase of the J/ψ production at backward rapidity with multiplicity is consistent with that observed in pp collisions. However, a deviation from this behavior in the J/ψ production at forward rapidity at high multiplicity has been measured. A trend towards saturation has also been observed in the J/ψ mean transverse momentum in p-Pb collisions. Whether these effects can be explained by cold nuclear matter effects or by the presence of further final state effects is currently under investigation. (author)

Collision-induced destructive quantum interference

International Nuclear Information System (INIS)

Yang Xihua; Sun Zhenrong; Zhang Shi'an; Ding Liang'en; Wang Zugeng

2005-01-01

We conduct theoretical studies on the collision-induced destructive quantum interference of two-colour two-photon transitions in an open rhomb-type five-level system with a widely separated doublet by the density matrix approach. The effects of the collision-induced decay rates, the ratio of the transition dipole moments and the energy separation of the doublet on the interference are analysed. It is shown that a narrow dip appears in the excitation spectrum due to the collision-induced destructive interference, and that the narrow interference dip still exists even when the collision broadening is comparable to the energy separation of the doublet. The physical origin of the collision-induced destructive quantum interference is analysed in the dressed-atom picture

Computed tomography to detect body packing: an unusual cause of small bowel obstruction

International Nuclear Information System (INIS)

Brown, J.A.; Phang, T.; Enns, R.; Butchart, M.K.; Filipenko, J.D.; Mason, A.C.; Cooperberg, P.I.

2002-01-01

Concealment of illicit drugs within the alimentary tract is now an established method used by both smugglers and traffickers to evade detection by authorities. Those who ingest wrapped packets of drugs to transport them across international borders are known as 'body packers,' whereas those who ingest packages of drugs upon an unexpected encounter with law enforcement agents are known as 'body stuffers' or 'quick swallowers. Although most of these individuals require no medical care, acute drug toxicity (from inadvertent leaking of contents or rupture of the drug packet) and bowel obstruction are recognized hazards of drug packet ingestion. The detection of these packets is a challenge to custom officials and police interested in preventing the import and trafficking of illegal drugs, as well as to physicians who have to treat individuals who have ingested them. We report a case of a 38-year-old intravenous drug abuser who presented with an acute small bowel obstruction secondary to an impacted intraluminal heroin balloon in the mid jejunum. The value of computed tomography (CT) in the patient's diagnostic evaluation is highlighted. (author)

17th century treatments of one-dimensional collisions

International Nuclear Information System (INIS)

Goehring, G.D.

1975-01-01

The issue of conservation in the collisions of bodies aroused considerable interest in the period of its initial investigation. Descartes asserted that the quantity of motion, the scalar product of the mass and speed, was the quantity that was conserved. Huygens, with the aid of his relativity of motion principle, recognized that it was not Descartes' scalar quantity that was conserved, but instead another scalar quality, the product of the mass and the square of the speed, whose total remained constant. Newton discovered that Descartes' quantity was conserved if considered a vector quantity, and thereby announced the principle of conservation of momentum. Leibniz recognized the conservation of Newton's momentum, and also the conservation of vis viva, the same scalar quantity that Huygens has earlier proposed. Although recognition of the immense importance of these principles had to await further developments in physics, the original formulation of these conservation principles, resulting from the analysis of one-dimensional collisions, was completed by the end of the 17th century. (U.K.)

Emittance increase caused by core depletion in collisions

CERN Document Server

Bruce, R

2009-01-01

A new effect is presented, which changes the emittance during colliding-beam operation in circular colliders. If the initial transverse distribution is Gaussian, the collision probability is much higher for particles in the core of the beam than in the tails. When small-amplitude particles are removed, the remaining ones therefore have a larger transverse emittance. This effect, called core depletion, may cause a decrease in luminosity. An approximate analytic model is developed to study the effect and benchmarked against a multiparticle tracking simulation. Finally, the time evolution of the intensity and emittances of a Pb bunch in the Large Hadron Collider (LHC) at CERN is calculated, taking into account also other processes than collisions. The results show that integrated luminosity drops by 3--4% if core depletion is taken into account. It is also found that core depletion causes the transverse emittance to be larger when more experiments are active. This observation could be checked against experimenta...

A Collective Collision Operator for DSMC

International Nuclear Information System (INIS)

Gallis, Michail A.; Torczynski, John R.

2000-01-01

A new scheme to simulate elastic collisions in particle simulation codes is presented. The new scheme aims at simulating the collisions in the highly collisional regime, in which particle simulation techniques typically become computationally expensive.The new scheme is based on the concept of a grid-based collision field. According to this scheme, the particles perform a single collision with the background grid during a time step. The properties of the background field are calculated from the moments of the distribution function accumulated on the grid. The collision operator is based on the Langevin equation. Based on comparisons with other methods, it is found that the Langevin method overestimates the collision frequency for dilute gases

Lower limb and associated injuries in frontal-impact road traffic collisions.

Science.gov (United States)

Ammori, Mohannad B; Eid, Hani O; Abu-Zidan, Fikri M

2016-03-01

To study the relationship between severity of injury of the lower limb and severity of injury of the head, thoracic, and abdominal regions in frontal-impact road traffic collisions. Consecutive hospitalised trauma patients who were involved in a frontal road traffic collision were prospectively studied over 18 months. Patients with at least one Abbreviated Injury Scale (AIS) ≥3 or AIS 2 injuries within two AIS body regions were included. Patients were divided into two groups depending on the severity of injury to the head, chest or abdomen. Low severity group had an AIS chest or abdominal injuries. Eighty-five patients were studied. The backward likelihood logistic regression model defining independent factors affecting severity of head injuries was highly significant (p =0.01, nagelkerke r square = 0.1) severity of lower limb injuries was the only significant factor (p=0.013) having a negative correlation with head injury (Odds ratio of 0.64 (95% CI: 0.45-0.91). Occupants who sustain a greater severity of injury to the lower limb in a frontal-impact collision are likely to be spared from a greater severity of head injury.

Distributed-Lagrange-Multiplier-based computational method for particulate flow with collisions

Science.gov (United States)

Ardekani, Arezoo; Rangel, Roger

2006-11-01

A Distributed-Lagrange-Multiplier-based computational method is developed for colliding particles in a solid-fluid system. A numerical simulation is conducted in two dimensions using the finite volume method. The entire domain is treated as a fluid but the fluid in the particle domains satisfies a rigidity constraint. We present an efficient method for predicting the collision between particles. In earlier methods, a repulsive force was applied to the particles when their distance was less than a critical value. In this method, an impulsive force is computed. During the frictionless collision process between two particles, linear momentum is conserved while the tangential forces are zero. Thus, instead of satisfying a condition of rigid body motion for each particle separately, as done when particles are not in contact, both particles are rigidified together along their line of centers. Particles separate from each other when the impulsive force is less than zero and after this time, a rigidity constraint is satisfied for each particle separately. Grid independency is implemented to ensure the accuracy of the numerical simulation. A comparison between this method and previous collision strategies is presented and discussed.

A quantum-mechanical study of atom-diatom collisions in a laser field

International Nuclear Information System (INIS)

Chang, Sintarng.

1989-01-01

A quantum-mechanical formalism, in both space-fixed (SF) and body-fixed (BF) coordinate systems, is developed for describing an S-state structureless atom (A) colliding with a Estate vibrating rotor diatomic molecule (BC) in the presence of a laser field. The additional Hamiltonians H rad and H int , which describe the laser field and its interaction with the atom-diatom collision system, have been added to the field-free Hamiltonian Ho. And the collision problem can be solved by this extended Hamiltonian. The laser field Hamiltonian is represented by the number state representation. The interaction Hamiltonian is expressed by rvec μ BC . rvec ε, where rvec μ BC is the dipole moment of the diatomic molecule BC, and rvec ε is the electric field strength of the laser field. Since the field-free total angular momentum J is coupling with the laser field, J and its z-axis projection M are no longer conserved. To facilitate the collision problem, the laser field is restricted to a single mode, and its interaction with the collision only involves dipole allowed transitions in which a single photon is absorbed or emitted. For convenience, the coupled-channel equations are solved by the real boundary conditions instead of the complex boundary conditions. On applying the real boundary conditions, the author obtains the K-matrix, which is related to the S-matrix by S = (I + iK)(I - iK) -1 . A model calculation is discussed for the Ar + CO collision system in a laser intensity of 10 9 W/cm 2

Neuromorphic UAS Collision Avoidance

Data.gov (United States)

National Aeronautics and Space Administration — Collision avoidance for unmanned aerial systems (UAS) traveling at high relative speeds is a challenging task. It requires both the detection of a possible collision...

Centrality dependence of particle production in p-Pb collisions at $\\sqrt{s_{\\rm NN} }$= 5.02 TeV

CERN Document Server

Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agostinelli, Andrea; Agrawal, Neelima; Ahammed, Zubayer; Ahmed, Ijaz; Ahn, Sang Un; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Alam, Sk Noor; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baltasar Dos Santos Pedrosa, Fernando; 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Zyzak, Maksym

2015-06-08

We report measurements of the primary charged particle pseudorapidity density and transverse momentum distributions in p-Pb collisions at $\\sqrt{s_{\\rm NN}}$ = 5.02 TeV, and investigate their correlation with experimental observables sensitive to the centrality of the collision. Centrality classes are defined using different event activity estimators, i.e. charged particle multiplicities measured in three disjunct pseudorapidity regions as well as the energy measured at beam rapidity (zero-degree). The procedures to determine the centrality, quantified by the number of participants ($N_{\\rm part}$), or the number of nucleon-nucleon binary collisions ($N_{\\rm coll}$), are described. We show that, in contrast to Pb-Pb collisions, in p-Pb collisions large multiplicity fluctuations together with the small range of participants available, generate a dynamical bias in centrality classes based on particle multiplicity. We propose to use the zero-degree energy, which we expect not to introduce a dynamical bias, as an...

Electromagnetic lepton-pair production in relativistic collisions

International Nuclear Information System (INIS)

Albert, C.J.; Ernst, D.J.; Strayer, M.R.; Bottcher, C.

1991-01-01

Electromagnetic lepton-pair production in relativistic collisions is studied in an ab initio approach with no free parameters. After a semi-classical approximation to the relative motion of the two incident particles is made, the resulting second-order diagram is calculated using a Monte Carlo technique to evaluate the resulting seven-dimensional integral. We examine the case of electron-positron pair production in π - p collisions at p pi = 17 GeV. We find that a significant fraction of the measured pairs in this reaction are produced via the magnetic spin-flip current of the proton. Approaches, such as the equivalent photon approximation, which neglect this part of the current predict much too small a cross section. This feature is traced to the cuts imposed in taking the experimental data. Lepton-pair production in the scattering of 3 He, 4 He and 4 He, 4 He is proposed as a clean way of experimentally separating the spin-flip and non-flip processes; predictions are made for these systems

Aerial vehicles collision avoidance using monocular vision

Science.gov (United States)

Balashov, Oleg; Muraviev, Vadim; Strotov, Valery

2016-10-01

In this paper image-based collision avoidance algorithm that provides detection of nearby aircraft and distance estimation is presented. The approach requires a vision system with a single moving camera and additional information about carrier's speed and orientation from onboard sensors. The main idea is to create a multi-step approach based on a preliminary detection, regions of interest (ROI) selection, contour segmentation, object matching and localization. The proposed algorithm is able to detect small targets but unlike many other approaches is designed to work with large-scale objects as well. To localize aerial vehicle position the system of equations relating object coordinates in space and observed image is solved. The system solution gives the current position and speed of the detected object in space. Using this information distance and time to collision can be estimated. Experimental research on real video sequences and modeled data is performed. Video database contained different types of aerial vehicles: aircrafts, helicopters, and UAVs. The presented algorithm is able to detect aerial vehicles from several kilometers under regular daylight conditions.

A top quark pair production event from proton-proton collisions recorded by ATLAS with LHC stable beams at a collision energy of 13 TeV

CERN Multimedia

ATLAS Collaboration

2015-01-01

Display of a candidate boosted top quark pair production event from proton-proton collisions recorded by ATLAS with LHC stable beams at a collision energy of 13 TeV. The red line shows the path of a muon with transverse momentum around 50 GeV through the detector. The dashed line shows the direction of the missing transverse momentum, which has a magnitude of about 470 GeV. The green and yellow bars indicate energy deposits in the liquid argon and scintillating-tile calorimeters, from these deposits 4 small-radius (R=0.4) jets are identified with transverse momenta between 70 and 300 GeV. Three of these small-radius jets are re-clustered into the leading large-radius (R=1.0) jet (not shown explicitly) with a transverse momentum of about 600 GeV and a jet mass of about 180 GeV, near the top quark mass. One of these three jets in addition to the fourth jet above 70 GeV are identified as having originated from b-quarks. Tracks reconstructed from hits in the inner tracking detector are shown as arcs curving in th...

Topics in atomic collision theory

CERN Document Server

Geltman, Sydney; Brueckner, Keith A

1969-01-01

Topics in Atomic Collision Theory originated in a course of graduate lectures given at the University of Colorado and at University College in London. It is recommended for students in physics and related fields who are interested in the application of quantum scattering theory to low-energy atomic collision phenomena. No attention is given to the electromagnetic, nuclear, or elementary particle domains. The book is organized into three parts: static field scattering, electron-atom collisions, and atom-atom collisions. These are in the order of increasing physical complexity and hence necessar

$\\phi$ Production in In-In Collisions at 158 A GeV

CERN Document Server

Arnaldi, R; Borer, K; Castor, J; Chaurand, B; Chen, W; Cicalò, C; Colla, A; Cortese, P; Damjanovic, S; David, A; de Falco, A; Devaux, A; Ducroux, L; En’yo, H; Fargeix, J; Ferretti, A; Floris, M; Förster, A; Force, P; Guettet, N; Guichard, A; Gulkanyan, H; Heuser, J; Keil, M; Kluberg, L; Li, Z; Lourenço, C; Lozano, J; Manso, F; Martins, P; Masoni, A; Neves, A; Ohnishi, H; Oppedisano, C; Parracho, P; Pillot, P; Poghosyan, T; Puddu, G; Radermacher, E; Ramalhete, P; Rosinsky, P; Scomparin, E; Seixas, J; Serci, S; Shahoyan, R; Sonderegger, P; Specht, H J; Tieulent, R; Uras, A; Usai, G; Veenhof, R; Wöhri, H K

2009-01-01

The NA60 experiment has measured muon pair production in In-In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of $\\phi\\to\\mu\\mu$ meson production. Differential spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity distribution is found to be constant as a function of centrality, compatible with previous results. The decay muon polar angle distribution is measured in several reference frames. No evidence of polarization is found as a function of transverse momentum and centrality. The analysis of the $p_{T}$ spectra shows that the $\\phi$ has a small radial flow, implying a weak coupling to the medium. The $T_{eff}$ parameter measured in In-In collisions suggests that the high value observed in Pb-Pb in the kaon channel is difficult to reconcile with radial flow alone. The absolute yield is compared to results in Pb-Pb collisions: though sig...

Three-Body Antikaon-Nucleon Systems

Czech Academy of Sciences Publication Activity Database

Shevchenko, Nina V.

2017-01-01

Roč. 58, č. 1 (2017), č. článku UNSP 6. ISSN 0177-7963 R&D Projects: GA ČR(CZ) GA15-04301S Institutional support: RVO:61389005 Keywords : three-body * antikaon-nucleon * K p interactions Subject RIV: BE - Theoretical Physics OBOR OECD: Atom ic, molecular and chemical physics (physics of atom s and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 0.877, year: 2016

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

Energy Technology Data Exchange (ETDEWEB)

Mehtar-Tani, Yacine [Institute of Nuclear Theory, University of Washington,Seattle, WA 98195-1550 (United States); Tywoniuk, Konrad [Theoretical Physics Department, CERN,1211 Geneva 23 (Switzerland)

2017-04-21

We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the “soft drop declustering” procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

Effects of large-angle Coulomb collisions on inertial confinement fusion plasmas.

Science.gov (United States)

Turrell, A E; Sherlock, M; Rose, S J

2014-06-20

Large-angle Coulomb collisions affect the rates of energy and momentum exchange in a plasma, and it is expected that their effects will be important in many plasmas of current research interest, including in inertial confinement fusion. Their inclusion is a long-standing problem, and the first fully self-consistent method for calculating their effects is presented. This method is applied to "burn" in the hot fuel in inertial confinement fusion capsules and finds that the yield increases due to an increase in the rate of temperature equilibration between electrons and ions which is not predicted by small-angle collision theories. The equilibration rate increases are 50%-100% for number densities of 10(30)  m(-3) and temperatures around 1 keV.

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

CERN Document Server

Mehtar-Tani, Yacine

2017-04-21

We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

Science.gov (United States)

Mehtar-Tani, Yacine; Tywoniuk, Konrad

2017-04-01

We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

International Nuclear Information System (INIS)

Mehtar-Tani, Yacine; Tywoniuk, Konrad

2017-01-01

We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the “soft drop declustering” procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

Muon transfer rates in collisions of hydrogen isotope mesic atoms on 'bare' nuclei. Multichannel adiabatic approach

International Nuclear Information System (INIS)

Korobov, V.I.; Melezhik, V.S.; Ponomarev, L.I.

1992-01-01

A numerical scheme for solving the problem of slow collisions in the three-body adiabatic approach is applied for calculation of muon transfer rates in collisions of hydrogen isotope atoms on bare nuclei. It is demonstrated that the multichannel adiabatic approach allows one to reach high accuracy results (∼3%) estimating the cross sections of charge transfer processes which are the best ones up to date. The method is appliable in a wide range of energies (0.001-50 eV) which is of interest for analysis of muon catalysed fusion experiments. 20 refs.; 3 figs.; 5 tabs

Representation of the Fokker-Planck collision term for Coulomb interaction as series of Legendre polynomials

International Nuclear Information System (INIS)

Almeida Ferreira, A.C. de.

1984-01-01

For problems with azimuthal symmetry in velocity space, the distribution function depends only on the speed and on the pitch angle. The angular dependence of the distribution function is expanded in Legendre polynomials, and the expansions of the collision integrals describing two-body Coulomb interactions in a plasma are determined through the use of the Rosenbluth potentials. The electron distribution function is written as a Maxwellian plus a deviation, and the representation in Legendre polynomials of the electron-electron collision term is given for both its linear and nonlinear part. To determine the representation of the electron-ion collision term it is assumed that the ion distribution is much narrower in velocity space than the electron distribution, and shifted from the origin by a flow velocity. The equations are presented in a form that is suitable for their use in a computer. (Author) [pt

A system for predicting close approaches and potential collisions in geosynchronous orbits

Science.gov (United States)

Beusch, J.; Abbot, R.; Sridharan, R.

The geosynchronous orbit is getting crowded with over 300 active, revenue producing large satellites and over 500 inactive dead resident space objects that pose a physical collision threat to the active satellites. The in situ demise of a particular satellite, Telstar 401, followed by a similar demise of SOLIDARIDAD 1, initiated a research and development effort at MIT Lincoln Laboratory to address this threat. This work with commercial satellite operators is accomplished using the mechanism of Cooperative Research and Development Agreements. Initial work to detect and warn of close approaches with these two failed satellites led to more extensive research on the collision threat over the entire geosynchronous belt. It is apparent that: a) There is a significant probability of collision; b) The probability has increased considerably in the last decade or so; c) The continuing failure of geosynchronous satellites and injection of rocket bodies into or near geosynchronous orbit will increase the threat; d) Debris in or near geosynchronous orbit poses another problem that has to be addressed. This paper surveys what has been achieved so far in predicting the threat and protecting satellites. An assessment of the probability of collision is presented as well as a description of the Geosynchronous Monitoring and Warning System. The operations of the GMWS are described as well as some of the results achieved so far. Areas of current research are mentioned.

E6 exotic quark production in ep collisions

International Nuclear Information System (INIS)

Hewett, J.L.

1987-06-01

We examine the possibility of producing exotic quarks from E 6 theories via flavor changing couplings in high energy ep collisions at HERA and the proposed LEP x LHC. We find that the rate is rather small and very mixing angle dependent. Assuming maximal mixing, the production rates are ≅10 to 30 events per year at HERA (for masses up to 100 GeV) and ≅200 events per year at LEP x LHC (for masses up to 300 GeV)

The Burden and Determinants of Neck Pain in Whiplash-Associated Disorders After Traffic Collisions

Science.gov (United States)

Carroll, Linda J.; Cassidy, J. David; Hogg-Johnson, Sheilah; Côté, Pierre; Guzman, Jamie; Peloso, Paul; Nordin, Margareta; Hurwitz, Eric; van der Velde, Gabrielle; Carragee, Eugene; Haldeman, Scott

2008-01-01

Study Design Best evidence synthesis. Objective To undertake a best evidence synthesis on the burden and determinants of whiplash-associated disorders (WAD) after traffic collisions. Study Design Summary of Background Data. Previous best evidence synthesis on WAD has noted a lack of evidence regarding incidence of and risk factors for WAD. Therefore there was a warrant of a reanalyze of this body of research. Methods A systematic search of Medline was conducted. The reviewers looked for studies on neck pain and its associated disorders published 1980 –2006. Each relevant study was independently and critically reviewed by rotating pairs of reviewers. Data from studies judged to have acceptable internal validity (scientifically admissible) were abstracted into evidence tables, and provide the body of the best evidence synthesis. Results The authors found 32 scientifically admissible studies related to the burden and determinants of WAD. In the Western world, visits to emergency rooms due to WAD have increased over the past 30 years. The annual cumulative incidence of WAD differed substantially between countries. They found that occupant seat position and collision impact direction were associated with WAD in one study. Eliminating insurance payments for pain and suffering were associated with a lower incidence of WAD injury claims in one study. Younger ages and being a female were both associated with filing claims or seeking care for WAD, although the evidence is not consistent. Preliminary evidence suggested that headrests/car seats, aimed to limiting head extension during rear-end collisions had a preventive effect on reporting WAD, especially in females. Conclusion WAD after traffic collisions affects many people. Despite many years of research, the evidence regarding risk factors for WAD is sparse but seems to include personal, societal, and environmental factors. More research including, well-defined studies with accurate denominators for calculating risk

Radiations from atomic collision processes

International Nuclear Information System (INIS)

Bernyi, D.

1994-01-01

The physics of atomic collision phenomena in which only the Coulomb forces have a role is an actual field or the research of the present days. The impact energy range in these collisions is very broad,it extends from the eV or even lower region to the GeV region or higher,i.e. it spans the region of three branches of physics,namely that of the atomic,the nuclear and the particle physics.To describe and explain the collision processes themselves, different models (collision mechanisms) are used and they are surveyed in the presentation. Different electromagnetic radiations and particles are emitted from the collision processes.Their features are shown in details together with the most important methods in their detection and study.Examples are given based on the literature and on the investigations of the author and his coworkers. The applications of the radiation from atomic collisions in other scientific fields and in the solution of different practical problems are also surveyed shortly. 16 figs., 2 tabs., 76 refs. (author)

Novel use of bioelectric impedence technique to detect alterations in body composition in advanced small cell lung cancer.

Science.gov (United States)

Mohan, A; Poulose, R; Ansari, A; Madan, K; Hadda, V; Khilnani, G C; Guleria, R

2017-01-01

Malnutrition is frequent in lung cancer and is measured using various tools, including the novel bioelectric impedance technique for measuring body composition. However, the validation of this technique for assessing body composition in advanced small cell lung cancer (SCLC) is untested. Forty-one treatment naïve patients (all males) and an equal number of age- and sex-matched controls were evaluated by anthropometric measurements of skinfold thicknesses and body composition parameters such as body fat%, fat mass, fat-free mass (FFM), and total body water (TBW). The mean (SD) age of the patient group was 55.7 (7.5) years, median pack-years was 20 (range, 0-80), and mean (SD) duration of symptoms was 152.6 (153.7) days. Median Karnofsky Performance Scale was 70 (range, 50-90). Majority of our patients (68.3%) were Stage IV followed by Stage III (31.7%). The percentage of patients with low, normal, and high body mass index (BMI) was 31.7%, 61%, and 7.3%, respectively. All components of body composition, i.e., body fat%, FFM, and TBW were significantly lower in patients compared to controls. However, the body composition in patients and controls with normal BMI was similar. The phenomenon of sarcopenia as a cause of cancer cachexia may explain these findings, whereas the combination of loss of body fat and lean body mass may lead to weight loss and reduced BMI. Our results indicate that body composition is markedly altered in Indian patients with advanced SCLC. The impact of these parameters on clinically relevant outcomes needs further evaluation.

Rapidity distributions of secondary particles in hadron-nucleus collisions

International Nuclear Information System (INIS)

Alaverdyan, G.B.; Pak, A.S.; Tarasov, A.V.; Tseren, Ch.; Uzhinsky, V.V.

1979-01-01

In the framework of the cascade model of a leading particle the rapidity distributions of secondary particles in the hadron-nucleus interactions are considered. The energy loss fluctuations of leading particles in the successive collisions have been taken into account. It is shown that the centre of rapidity distribution is displaced towards small rapidity with target nucleus atomic number A growth. The model well reproduces the energy and A dependences of the rapidity distributions

Early time evolution of high-energy heavy-ion collisions

Energy Technology Data Exchange (ETDEWEB)

Fries, Rainer J [Cyclotron Institute and Department of Physics, Texas A and M University, College Station, TX 77843 (United States); RIKEN/BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2007-08-15

We solve the Yang-Mills equations in the framework of the McLerran-Venugopalan model for small times {tau} after a collision of two nuclei. An analytic expansion around {tau} = 0 leads to explicit results for the field strength and the energy-momentum tensor of the gluon field at early times. We then discuss constraints for the energy density, pressure and flow of the plasma phase that emerges after thermalization of the gluon field.

On the interaction of small-scale linear waves with nonlinear solitary waves

Science.gov (United States)

Xu, Chengzhu; Stastna, Marek

2017-04-01

In the study of environmental and geophysical fluid flows, linear wave theory is well developed and its application has been considered for phenomena of various length and time scales. However, due to the nonlinear nature of fluid flows, in many cases results predicted by linear theory do not agree with observations. One of such cases is internal wave dynamics. While small-amplitude wave motion may be approximated by linear theory, large amplitude waves tend to be solitary-like. In some cases, when the wave is highly nonlinear, even weakly nonlinear theories fail to predict the wave properties correctly. We study the interaction of small-scale linear waves with nonlinear solitary waves using highly accurate pseudo spectral simulations that begin with a fully nonlinear solitary wave and a train of small-amplitude waves initialized from linear waves. The solitary wave then interacts with the linear waves through either an overtaking collision or a head-on collision. During the collision, there is a net energy transfer from the linear wave train to the solitary wave, resulting in an increase in the kinetic energy carried by the solitary wave and a phase shift of the solitary wave with respect to a freely propagating solitary wave. At the same time the linear waves are greatly reduced in amplitude. The percentage of energy transferred depends primarily on the wavelength of the linear waves. We found that after one full collision cycle, the longest waves may retain as much as 90% of the kinetic energy they had initially, while the shortest waves lose almost all of their initial energy. We also found that a head-on collision is more efficient in destroying the linear waves than an overtaking collision. On the other hand, the initial amplitude of the linear waves has very little impact on the percentage of energy that can be transferred to the solitary wave. Because of the nonlinearity of the solitary wave, these results provide us some insight into wave-mean flow

Collision of H+ + CH4 at 30 eV: A simulation study

International Nuclear Information System (INIS)

Gao, Cong-Zhang; Wang, Jing; Zhang, Feng-Shou

2013-01-01

The process of proton impinging upon CH 4 molecule has been theoretically studied at 30 eV. The study is based on time-dependent local density approximation coupled with molecular dynamics model. The electronic density evolution, ionic motion, and the scattering angle are presented. We found that the mechanism of target ionization in present simulation is electron capture. The predicted rainbow angle is in good agreement with experiments and previous calculations. By comparing the scattering angle from present calculation with that from classical collision, we found that the nuclear stopping is dominant in small impact parameters, and the discrepancy in large impact parameters may be due to the neglect of electronic stopping in classical collision

Collision of the glass shards with the eye: A computational fluid-structure interaction model.

Science.gov (United States)

Karimi, Alireza; Razaghi, Reza; Biglari, Hasan; Sera, Toshihiro; Kudo, Susumu

2017-12-27

The main stream of blunt trauma injuries has been reported to be related to the automobile crashes, sporting activities, and military operations. Glass shards, which can be induced due to car accident, earthquake, gunshot, etc., might collide with the eye and trigger substantial scarring and, consequently, permanently affect the vision. The complications as a result of the collision with the eye and its following injuries on each component of the eye are difficult to be diagnosed. The objective of this study was to employ a Three-Dimensional (3D) computational Fluid-Structure Interaction (FSI) model of the human eye to assess the results of the glass shards collision with the eye. To do this, a rigid steel-based object hit a Smoothed-Particle Hydrodynamics (SPH) glass wall at the velocities of 100, 150, and 200 m/s and, subsequently, the resultant glass shards moved toward the eye. The amount of injury, then, quantified in terms of the stresses and strains. The results revealed the highest amount of stress in the cornea while the lowest one was observed in the vitreous body. It was also found that increasing the speed of the glass shards amplifies the amount of the stress in the components which are located in the central anterior zone of the eye, such as the cornea, aqueous body, and iris. However, regarding those components located in the peripheral/posterior side of the eye, especially the optic nerve, by increasing the amount of velocity a reduction in the stresses was observed and the optic nerve is hardly damaged. These findings have associations not only for understanding the amount of stresses/strains in the eye components at three different velocities, but also for providing preliminary information for the ophthalmologists to have a better diagnosis after glass shards (small objects impact) injuries to the eye. Copyright © 2017 Elsevier B.V. All rights reserved.

New Development on Modelling Fluctuations and Fragmentation in Heavy-Ion Collisions

Science.gov (United States)

Lin, Hao; Danielewicz, Pawel

2017-09-01

During heavy-ion collisions (HIC), colliding nuclei form an excited composite system. Instabilities present in the system may deform the shape of the system exotically, leading to a break-up into fragments. Many experimental efforts have been devoted to the nuclear multifragmentation phenomenon, while traditional HIC models, lacking in proper treatment of fluctuations, fall short in explaining it. In view of this, we are developing a new model to implement realistic fluctuations into transport simulation. The new model is motivated by the Brownian motion description of colliding particles. The effects of two-body collisions are recast in one-body diffusion processes. Vastly different dynamical paths are sampled by solving Langevin equations in momentum space. It is the stochastic sampling of dynamical paths that leads to a wide spread of exit channels. In addition, the nucleon degree of freedom is used to enhance the fluctuations. The model has been tested in reactions such as 112Sn + 112Sn and 58Ni + 58Ni, where reasonable results are yielded. An exploratory comparison on the 112Sn + 112Sn reaction at 50 MeV/nucleon with two other models, the stochastic mean-field (SMF) and the antisymmetrized molecular dynamics (AMD) models, has also been conducted. Work supported by the NSF Grant No. PHY-1403906.

Multifragmentation in Au + Au collisions studied with AMD-V

Energy Technology Data Exchange (ETDEWEB)

Ono, Akira [Tohoku Univ., Sendai (Japan). Faculty of Science

1998-07-01

AMD-V is an optimum model for calculation of multifragmentation in Au + Au collisions. AMD-V consider anti-symmetry of incident nucleus, target nucleus and fragments, furthermore, it treat the quantum effect to exist many channels in the intermediate and final state. 150 and 250 MeV/nucleon incident energy were used in the experiments. The data of multifragment atom in {sup 197}Au + {sup 197}Au collisions was reproduced by AMD-V calculation using Gognny force, corresponding to the imcompressibility of nuclear substance K = 228 MeV and its mean field depend on momentum. When other interaction (SKG 2 force, corresponding to K = 373 KeV) was used an mean field does not depend on momentum, the calculation results could not reproduce the experimental values, because nucleus and deuteron were estimated too large and {alpha}-particle and intermediate fragments estimated too small. (S.Y.)

Searches for two-body charmless baryonic $B^0$ decays at LHCb

CERN Document Server

AUTHOR|(CDS)2083570; Eklund, Lars

2016-09-26

The results of two separate searches for the rare two-body charmless baryonic decays B0 -> p pbar and B0s -> p pbar at the LHCb experiment are reported in this thesis. The first analysis uses a data sample, corresponding to an integrated luminosity of 0.9 fb^-1, of proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. An excess of B0 -> p pbar candidates with respect to background expectations is seen with a statistical significance of 3.3 standard deviations. This constitutes the first evidence for a two-body charmless baryonic B0 decay. No significant B0s -> p pbar signal was observed. However, a small excess of B0s -> p pbar events allowed the extraction of two sided confidence level intervals for the B0s -> p pbar branching fraction using the Feldman-Cousins frequentist method. This improved the upper limit on the B0s -> p pbar branching fraction by three orders of magnitude over previous bounds. The 68.3% confidence level intervals on the branching fractions w...

Collision-induced post-plateau volcanism: Evidence from a seamount on Ontong Java Plateau

Science.gov (United States)

Hanyu, Takeshi; Tejada, Maria Luisa G.; Shimizu, Kenji; Ishizuka, Osamu; Fujii, Toshiyuki; Kimura, Jun-Ichi; Chang, Qing; Senda, Ryoko; Miyazaki, Takashi; Hirahara, Yuka; Vaglarov, Bogdan S.; Goto, Kosuke T.; Ishikawa, Akira

2017-12-01

Many seamounts on the Ontong Java Plateau (OJP) occur near the Stewart Arch, a topographic high that extends parallel to the North Solomon Trench along the southern margins of the plateau. Despite the thick sediment cover, several volcanic cones with strong acoustic reflection were discovered on the submarine flank of the Nuugurigia Seamount. From such volcanic cones, basalts were successfully sampled by dredging. Radiometric dating of basalts and ferromanganese encrustation indicate eruption age of 20-25 Ma, significantly younger than the 122 Ma main OJP plateau and post-plateau basalts. The age range coincides with the collision of the OJP with the Solomon Arc. The Nuugurigia basalts geochemically differ from any other rocks sampled on the OJP so far. They are alkali basalts with elevated Sr, low Zr and Hf, and Enriched Mantle-I (EMI)-like isotopic composition. Parental magmas of these alkali basalts may have formed by small-degree melting of peridotitic mantle impregnated with recycled pyroxenite material having enriched geochemical composition in the OJP's mantle root. We conclude that small-volume alkali basalts from the enriched mantle root migrated through faults or fractures caused by the collision along the Stewart Arch to form the seamount. Our results suggest that the collision of the OJP with the Solomon arc played an important role in the origin of similar post-plateau seamounts along the Stewart Arch.

Quantum-mechanical theory for electronic-vibrational-rotational energy transfer in atom--diatom collisions: Analysis of the Hamiltonian

International Nuclear Information System (INIS)

Bellum, J.C.; McGuire, P.

1983-01-01

We investigate forms of the molecular system Hamiltonian valid for rigorous quantum-mechanical treatments of inelastic atom--diatom collisions characterized by exchange of energy between electronic, vibrational, and rotational degrees of freedom. We analyze this Hamiltonian in terms of various choices of independent coordinates which unambiguously specify the electronic and nuclear positions in the context of space-fixed and body-fixed reference frames. In particular we derive forms of the Hamiltonian in the context of the following four sets of independent coordinates: (1) a so-called space-fixed set, in which both electronic and nuclear positions are relative to the space-fixed frame; (2) a so-called mixed set, in which nuclear positions are relative to the body-fixed frame while electronic positions are relative to the space-fixed frame; (3) a so-called body-fixed set, in which both electronic and nuclear positions are relative to the body-fixed frame; and (4) another mixed set, in which nuclear positions are relative to the space-fixed frame while electronic positions are relative to the body-fixed frame. Based on practical considerations in accounting for electronic structure and nonadiabatic coupling of electronic states of the collision complex we find the forms of the Hamiltonian in the context of coordinate sets (3) and (4) above to be most appropriate, respectively, for body-fixed and space-fixed treatments of nuclear dynamics in collisional transfer of electronic, vibrational, and rotational energies

Collisions of neutrons and of gamma rays in Bi4Ge3O12 (BGO) and NaI(Tl) scintillation detectors

International Nuclear Information System (INIS)

Kushneriuk, S.A.; Lone, M.A.; Hausser, O.; Wong, P.Y.

1983-06-01

The role of collision/escape probabilities in establishing the prompt response of bismuth germanate and NaI(Tl) scintillators is investigated. A possible approximation to the collision probability is discussed. Exact expressions for the probability of escape of radiation from finite, right circular cylindrical and rectangular parallelepiped-shaped detectors are derived from an exponential-like spatial distribution of the source in the detector medium and a parametrized angular distribution of emission of the source. Fairly extensive tables of collision probabilities calculated for these bodies are given. For purposes of comparison some results obtained previously in a Monte Carlo calculation are also presented and discussed

Translational Entanglement and Teleportation of Matter Wavepackets by Collisions and Half-Collisions

Science.gov (United States)

Fisch, L.; Tal, A.; Kurizki, G.

To date, the translationally-entangled state originally proposed by Einstein, Podolsky and Rosen (EPR) in 1935 has not been experimentally realized for massive particles. Opatrný and Kurizki [Phys. Rev. Lett. 86, 3180 (2000)] have suggested the creation of a position- and momentum-correlated, i.e., translationally-entangled, pair of particles approximating the EPR state by dissociation of cold diatomic molecules, and further manipulation of the EPR pair effecting matter-wave teleportation. Here we aim at setting the principles of and quantifying translational entanglement by collisions and half-collisions. In collisions, the resonance width s and the initial phase-space distributions are shown to determine the degree of post-collisional momentum entanglement. Half-collisions (dissociation) are shown to yield different types of approximate EPR states. We analyse a feasible realization of translational EPR entanglement and teleportation via cold-molecule Raman dissociation and subsequent collisions, resolving both practical and conceptual difficulties it has faced so far: How to avoid entanglement loss due to the wavepacket spreading of the dissociation fragments? How to measure both position and momentum correlations of the dissociation fragments with sufficient accuracy to verify their EPR correlations? How to reliably perform two-particle (Bell) position and momentum measurements on one of the fragments and the wavepacket to be teleported?

Design of an Active Bumper with a Series Elastic Actuator for Pedestrian Protection of Small Unmanned Vehicles

Science.gov (United States)

Terumasa, Narukawa; Tomoki, Tsuge; Hiroshi, Yamamoto; Takahiro, Suzuki

2016-09-01

When autonomous unmanned vehicles are operated on sidewalks, the vehicles must have high safety standards such as avoiding injury when they come in contact with pedestrians. In this study, we established a design for preventing serious injury when such collisions occur. We designed an active bumper with a series elastic actuator, with the goal of avoiding serious injury to a pedestrian in a collision with a small unmanned vehicle. The series elastic actuator comprised an elastic element in series with a table driven by a ball screw and servo motor. The active bumper was used to control the contact force between a vehicle and a pedestrian. The optimal force for minimizing the deflection of the object of the collision was derived, and the actuator controlled to apply this optimal force. Numerical simulations showed that the active bumper was successful in improving the collision safety of small unmanned vehicles.

Stereotactic Ablative Body Radiation Therapy for Octogenarians With Non-Small Cell Lung Cancer

Energy Technology Data Exchange (ETDEWEB)

Takeda, Atsuya; Sanuki, Naoko; Eriguchi, Takahisa [Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa (Japan); Kaneko, Takeshi [Respiratory Disease Center, Yokohama City University Medical Center, Kanagawa (Japan); Department of Respirology, Ofuna Chuo Hospital, Kanagawa (Japan); Morita, Satoshi [Department of Biostatistics and Epidemiology, Graduate School of Medicine, Yokohama City University, Kanagawa (Japan); Handa, Hiroshi [Respiratory Disease Center, Yokohama City University Medical Center, Kanagawa (Japan); Division of Respiratory and Infectious Diseases, Department of Internal Medicine, St. Marianna University School of Medicine, Kanagawa (Japan); Aoki, Yousuke; Oku, Yohei [Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa (Japan); Kunieda, Etsuo, E-mail: kunieda-mi@umin.ac.jp [Department of Radiation Oncology, Tokai University, Kanagawa (Japan)

2013-06-01

Purpose: To retrospectively investigate treatment outcomes of stereotactic ablative body radiation therapy (SABR) for octogenarians with non-small cell lung cancer (NSCLC). Methods and Materials: Between 2005 and 2012, 109 patients aged ≥80 years with T1-2N0M0 NSCLC were treated with SABR: 47 patients had histology-unproven lung cancer; 62 patients had pathologically proven NSCLC. The prescribed doses were either 50 Gy/5 fractions for peripheral tumors or 40 Gy/5 fractions for centrally located tumors. The treatment outcomes, toxicities, and the correlating factors for overall survival (OS) were evaluated. Results: The median follow-up duration after SABR was 24.2 (range, 3.0-64.6) months. Only limited toxicities were observed, except for 1 grade 5 radiation pneumonitis. The 3-year local, regional, and distant metastasis-free survival rates were 82.3%, 90.1%, and 76.8%, respectively. The OS and lung cancer-specific survival rates were 53.7% and 70.8%, respectively. Multivariate analysis revealed that medically inoperable, low body mass index, high T stage, and high C-reactive protein were the predictors for short OS. The OS for the operable octogenarians was significantly better than that for inoperable (P<.01). Conclusions: Stereotactic ablative body radiation therapy for octogenarians was feasible, with excellent OS. Multivariate analysis revealed that operability was one of the predictors for OS. For medically operable octogenarians with early-stage NSCLC, SABR should be prospectively compared with resection.

High energy hadron-nucleus collision

International Nuclear Information System (INIS)

Takagi, Fujio

1983-02-01

This is a lecture note concerning high energy hadron-nucleus collision. The lecture gives the inelastic total cross section and the Glanber approximate multiple scattering formula at first. The mechanism of nuclear spallation is described in a cylindrical image. The multiplicity, the one particle distribution and the time-space structure of particle production are discussed. Various models are presented. The attenuation of forward particles and the structure of hadrons are discussed for each model. The atomic number (A) dependence of the production of large transverse momentum particles and jet, and the A dependence of charged multiplicity are presented. The backward production of particles and many body correlation are discussed. Lepton pair production and the initial interaction of constituents, collective interaction, multi quark state and phase transition are described. (Kato, T.)

Nuclear matter flow in the Kr+Au collisions at 43 MeV/u

International Nuclear Information System (INIS)

Bougault, R.; Delaunay, F.; Genoux-Lubain, A.; Lebrun, C.; Lecolley, J.F.; Lefebvres, F.; Louvel, M.; Steckmeyer, J.C.; Aloff, J.C.; Bilwes, B.; Bilwes, R.; Glaser, M.; Rudolf, G.; Scheibling, F.; Stuttge, L.

1989-01-01

When heavy nuclei collide at energy far above the Coulomb barrier we may study the property of nuclear matter in temperature and also density regions far away from the equilibrium. We then hope to study dynamical effects related to the compressibility and the two body collision term. At relativistic energies, some collective effects (flow, bounce off) have been established from a shape analysis done with a large number of light particles with Z ≤ 10. For incident energies lower than 100 MeV/u we may expect that the number of nuclear species formed will be smaller and that a large part of the nuclear matter involved in the collision will be shared in a limited number of heavy fragments (Z ≥ 10). If dynamical effects are still present at GANIL energies they ought to manifest themselves through the properties of the produced fragments (masses, emission angles, velocities and correlated variables). We will present an analysis of heavy nuclei collisions at 43 MeV/u based on as exclusive as possible detection of large fragments

Resonance production in central pp collisions at the CERN Omega Spectrometer

CERN Document Server

Kirk, A.

2000-01-01

A study of resonance production in central pp collisions is presented as a function of several kinematical variables. In particular the difference in the transverse momentum (dPT) of the exchanged particles shows that undisputed qqbar mesons are suppressed at small dPT whereas glueball candidates are enhanced and in addition, the azimuthal angle phi gives information on the nature of the Pomeron.

NA49: lead-lead collision

CERN Multimedia

1996-01-01

This is an image of an actual lead ion collision taken from tracking detectors on the NA49 experiment, part of the heavy ion project at CERN. These collisions produce a very complicated array of hadrons as the heavy ions break up. It is hoped that one of these collisions will eventually create a new state of matter known as quark-gluon plasma.

From collisions to clusters

DEFF Research Database (Denmark)

Loukonen, Ville; Bork, Nicolai; Vehkamaki, Hanna

2014-01-01

-principles molecular dynamics collision simulations of (sulphuric acid)1(water)0, 1 + (dimethylamine) → (sulphuric acid)1(dimethylamine)1(water)0, 1 cluster formation processes. The simulations indicate that the sticking factor in the collisions is unity: the interaction between the molecules is strong enough...... control. As a consequence, the clusters show very dynamic ion pair structure, which differs from both the static structure optimisation calculations and the equilibrium first-principles molecular dynamics simulations. In some of the simulation runs, water mediates the proton transfer by acting as a proton...... to overcome the possible initial non-optimal collision orientations. No post-collisional cluster break up is observed. The reasons for the efficient clustering are (i) the proton transfer reaction which takes place in each of the collision simulations and (ii) the subsequent competition over the proton...

A parallel Discrete Element Method to model collisions between non-convex particles

Directory of Open Access Journals (Sweden)

Rakotonirina Andriarimina Daniel

2017-01-01

Full Text Available In many dry granular and suspension flow configurations, particles can be highly non-spherical. It is now well established in the literature that particle shape affects the flow dynamics or the microstructure of the particles assembly in assorted ways as e.g. compacity of packed bed or heap, dilation under shear, resistance to shear, momentum transfer between translational and angular motions, ability to form arches and block the flow. In this talk, we suggest an accurate and efficient way to model collisions between particles of (almost arbitrary shape. For that purpose, we develop a Discrete Element Method (DEM combined with a soft particle contact model. The collision detection algorithm handles contacts between bodies of various shape and size. For nonconvex bodies, our strategy is based on decomposing a non-convex body into a set of convex ones. Therefore, our novel method can be called “glued-convex method” (in the sense clumping convex bodies together, as an extension of the popular “glued-spheres” method, and is implemented in our own granular dynamics code Grains3D. Since the whole problem is solved explicitly, our fully-MPI parallelized code Grains3D exhibits a very high scalability when dynamic load balancing is not required. In particular, simulations on up to a few thousands cores in configurations involving up to a few tens of millions of particles can readily be performed. We apply our enhanced numerical model to (i the collapse of a granular column made of convex particles and (i the microstructure of a heap of non-convex particles in a cylindrical reactor.

The epidemiology of bicyclist's collision accidents

DEFF Research Database (Denmark)

Larsen, L. B.

1994-01-01

of bicyclists and risk situations. The findings should make a basis for preventive programmes in order to decrease the number and severity of bicyclists collision accidents. Data from the emergency room in a 2 year period was combined with data from questionnaires. The study group consisted of 1021 bicyclists......The number of bicyclists injured in the road traffic in collision accidents and treated at the emergency room at Odense University Hospital has increased 66% from 1980 to 1989. The aim of this study was to examine the epidemiology of bicyclist's collision accidents and identify risk groups...... injured in collision accidents, and 1502 bicyclists injured in single accidents was used as a reference group. The young bicyclists 10-19 years of age had the highest incidence of injuries caused by collision accidents. The collision accidents had different characteristics according to counterpart. One...

Fragment ion distribution in charge-changing collisions of 2-MeV Si ions with C60

Science.gov (United States)

Itoh, A.; Tsuchida, H.; Miyabe, K.; Majima, T.; Nakai, Y.

2001-09-01

We have measured positive fragment ions produced in collisions of 2 MeV Siq+ (q=0, 1, 2, 4) projectiles with a C60 molecular target. The measurement was performed with a time-of-flight coincidence method between fragment ions and charge-selected outgoing projectiles. For all the charge-changing collisions investigated here, the mass distribution of small fragment ions C+n (n=1-12) can be approximated fairly well by a power-law form of n-λ as a function of the cluster size n. The power λ derived from each mass distribution is found to change strongly according to different charge-changing collisions. As a remarkable experimental finding, the values of λ(loss) in electron loss collisions are almost the same for the same final charge states k irrespective of the initial charge q, exhibiting a nearly perfect linear relationship with k. We also performed calculations of the projectile ionization on the basis of the semiclassical approximation and obtained inelastic energy deposition for individual collision processes. The estimated energy deposition is found to have a simple correlation with the experimentally determined values of λ(loss).

Body size, energy use, and community structure of small mammals

OpenAIRE

Ernest, S.K. Morgan

2005-01-01

Body size has long been hypothesized to play a major role in community structure and dynamics. Two general hypotheses exist for how resources are distributed among body sizes: (1) resources are equally available and uniformly utilized across body sizes and (2) resources are differentially available to organisms of different body sizes, resulting in a nonuniform or modal distribution. It has also been predicted that the distri-bution of body sizes of species in a community should reflect the u...

Comment on "Penetration of Action Potentials During Collision in the Median and Lateral Giant Axons of Invertebrates"

Science.gov (United States)

Berg, Rune W.; Stauning, Marius Tving; Sørensen, Jakob Balslev; Jahnsen, Henrik

2017-04-01

The action potential (AP) is an electrical impulse elicited by depolarization of the neuronal membrane from the resting membrane potential (around -70 mV ). It propagates along the axon, allowing for rapid and distant communication. Recently, it was claimed that two APs traveling in opposite direction will pass unhindered through each other (penetrate) upon collision [Gonzalez-Perez et al.Phys. Rev. X 4, 031047 (2014), 10.1103/PhysRevX.4.031047]. We tested this claim under carefully controlled conditions and found that we cannot reproduce penetration. Instead, APs consistently annihilated upon collision. This is consistent with a vast body of literature.

Computed tomography to detect body packing: an unusual cause of small bowel obstruction

Energy Technology Data Exchange (ETDEWEB)

Brown, J.A. [St. Paul' s Hospital, Dept. of Radiology, Vancouver, British Columbia (Canada); Phang, T. [St. Paul' s Hospital, Dept. of Surgery, Vancouver, British Columbia (Canada); Enns, R. [St. Paul' s Hospital, Div. of Gastroenterology, Dept. of Internal Medicine, Vancouver, British Columbia (Canada); Butchart, M.K. [St. Paul' s Hospital, Dept. of Radiology, Vancouver, British Columbia (Canada); Filipenko, J.D. [St. Paul' s Hospital, Dept. of Pathology, Vancouver, British Columbia (Canada); Mason, A.C.; Cooperberg, P.I. [St. Paul' s Hospital, Dept. of Radiology, Vancouver, British Columbia (Canada)

2002-04-01

Concealment of illicit drugs within the alimentary tract is now an established method used by both smugglers and traffickers to evade detection by authorities. Those who ingest wrapped packets of drugs to transport them across international borders are known as 'body packers,' whereas those who ingest packages of drugs upon an unexpected encounter with law enforcement agents are known as 'body stuffers' or 'quick swallowers. Although most of these individuals require no medical care, acute drug toxicity (from inadvertent leaking of contents or rupture of the drug packet) and bowel obstruction are recognized hazards of drug packet ingestion. The detection of these packets is a challenge to custom officials and police interested in preventing the import and trafficking of illegal drugs, as well as to physicians who have to treat individuals who have ingested them. We report a case of a 38-year-old intravenous drug abuser who presented with an acute small bowel obstruction secondary to an impacted intraluminal heroin balloon in the mid jejunum. The value of computed tomography (CT) in the patient's diagnostic evaluation is highlighted. (author)

Overpopulation of $\\bar \\Omega$ in pp collisions a way to distinguish statistical hadronization from string dynamics

CERN Document Server

Bleicher, M; Keränen, A; Aichelin, Jörg; Bass, S A; Becattini, F; Redlich, Krzysztof; Werner, K

2002-01-01

The $\\bar{\\Omega}/\\Omega$ ratio originating from string decays is predicted to be larger than unity in proton proton interactions at SPS energies ($E_{\\rm lab}$=160 GeV). The anti-omega dominance increases with decreasing beam energy. This surprising behavior is caused by the combinatorics of quark-antiquark production in small and low-mass strings. Since this behavior is not found in a statistical description of hadron production in proton proton collisions, it may serve as a key observable to probe the hadronization mechanism in such collisions.

Peripheral collisions in Ar induced reactions between 27 and 44 A.MeV: study of energy dissipation by measuring the correlated neutron multiplicities

International Nuclear Information System (INIS)

Guerreau, D.; Doubre, H.; Galin, J.; Pouthas, J.; Jahnke, U.; Jiang, D.X.; Lott, B.; Jacquet, D.

1988-01-01

A 4 π detector measuring the neutron multiplicities has been used to investigate the energy dissipation during peripheral collisions in Ar induced reactions around the Fermi Energy. Besides the persistance of direct transfer reactions for the most peripheral collisions, there are strong evidences for the occurrence of quite large energy dissipation, a clear signature for the one body friction to still play a major role at these intermediate energies

Coupled-channels calculations of excitation and ionization in ion-atom collisions

International Nuclear Information System (INIS)

Martir, M.H.

1981-01-01

A numerical method has been used to compute excitation and ionization cross sections for ion-atom collisions. The projectile is treated classically and follows a straight line, constant velocity path (unless indicated otherwise). The wave function that describes the atom is expanded about the target in a truncated Hilbert space. The interaction between the projectile and the target atom is treated as a time dependent perturbation. A unitary time development operator, U, propagates the wave function from a time prior to the collision to a time after the collision in small time steps. Contrary to first-order theories, coupling between states is allowed. This method has been improved so that any number of partial waves can be included in the wave function expansion. This method has been applied to study negatively charged projectiles. Cross sections are obtained for collisions of antiprotons on atomic hydrogen (30 keV to 372 keV) and compared with cross sections of protons on atomic hydrogen to explore the Z/sub P/ dependence. The antiproton-hydrogen results were converted into electron-hydrogen values with E/sub e/ = E/sub P/(m/sub e//m/sub P/) (15 eV to 200 eV) and compared to experimental values. The method is then applied to study vacancy production from the L-shell. The partial wave convergence of the cross sections was carefully studied for s through g waves. Collisions between protons (and alpha-particles) and argon are studied to explore the Z/sub P/ dependence of the cross sections. The cross section ratio sigma(α)/(4sigma(p)) is compared to experiment