A LINEAR INDUCTION PUMP FOR LIQUID METALS

A linear induction pump of a special design was used to circulate molten sodium through a mockup of an experimental "overflow" type of sodium-cooled reactor. The distinctive features of this pump are that no seals or moving parts are required: no piping is required to carry sodium to the pump or away from it because the pump is mounted directly on the reactor vessel, with the windings outside of the vessel and the magnetic flux return path inside the vessel. The pump develops 342 gpm at 6.2 psi when pumping sodium at 600 deg F with an efficiency of 4.7%. (auth

Time-dependent 3-D dterministic transport on parallel architectures using Dantsys/MPI

In addition to the ability to solve the static transport equation, we have also incorporated time dependence into our parallel 3-D S{sub {ital N}} code DANTSYS/MPI. Using a semi-implicit scheme, DANTSYS/MPI is capable of performing time-dependent calculations for both fissioning and pure source driven problems. We have applied this to various types of problems such as nuclear well logging and prompt fission experiments. This paper describes the form of the time- dependent equations implemented, their solution strategies in DANTSYS/MPI including iteration acceleration, and the strategies used for time-step control. Results are presented for a model nuclear well logging calculation

DANTSYS: a system for deterministic, neutral particle transport calculations

The THREEDANT code is the latest addition to our system of codes, DANTSYS, which perform neutral particle transport computations on a given system of interest. The system of codes is distinguished by geometrical or symmetry considerations. For example, ONEDANT and TWODANT are designed for one and two dimensional geometries respectively. We have TWOHEX for hexagonal geometries, TWODANT/GQ for arbitrary quadrilaterals in XY and RZ geometry, and THREEDANT for three-dimensional geometries. The design of this system of codes is such that they share the same input and edit module and hence the input and output is uniform for all the codes (with the obvious additions needed to specify each type of geometry). The codes in this system are also designed to be general purpose solving both eigenvalue and source driven problems. In this paper we concentrate on the THREEDANT module since there are special considerations that need to be taken into account when designing such a module. The main issues that need to be addressed in a three-dimensional transport solver are those of the computational time needed to solve a problem and the amount of storage needed to accomplish that solution. Of course both these issues are directly related to the number of spatial mesh cells required to obtain a solution to a specified accuracy, but is also related to the spatial discretization method chosen and the requirements of the iteration acceleration scheme employed as will be noted below. Another related consideration is the robustness of the resulting algorithms as implemented; because insistence on complete robustness has a significant impact upon the computation time. We address each of these issues in the following through which we give reasons for the choices we have made in our approach to this code. And this is useful in outlining how the code is evolving to better address the shortcomings that presently exist

DANTSYS/MPI: a system for 3-D deterministic transport on parallel architectures

Since 1994, we have been using a data parallel form of our deterministic transport code DANTSYS to perform time-independent fixed source and eigenvalue calculations on the CM-200`s at Los Alamos National Laboratory (LANL). Parallelization of the transport sweep is obtained by using a 2-D spatial decomposition which retains the ability to invert the source iteration equation in a single iteration (i.e., the diagonal plane sweep). We have now implemented a message passing version of DANTSYS, referred to as DANTSYS/MPI, on the Cray T3D installed at Los Alamos in 1995. By taking advantage of the SPMD (Single Program, Multiple Data) architecture of the Cray T3D, as well as its low latency communications network, we have managed to achieve grind times (time to solve a single cell in phase space) of less than 10 nanoseconds on the 512 PE (Processing Element) T3D, as opposed to typical grind times of 150-200 nanoseconds on a 2048 PE CM-200, or 300-400 nanoseconds on a single PE of a Cray Y-MP. In addition, we have also parallelized the Diffusion Synthetic Accelerator (DSA) equations which are used to accelerate the convergence of the transport equation. DANTSYS/MPI currently runs on traditional Cray PVP`s and the Cray T3D, and it`s computational kernel (Sweep3D) has been ported to and tested on an array of SGI SMP`s (Symmetric Memory Processors), a network of IBM 590 workstations, an IBM SP2, and the Intel TFLOPs machine at Sandia National Laboratory. This paper describes the implementation of DANTSYS/MPI on the Cray T3D, and presents a simple performance model which accurately predicts the grind time as a function of the number of PE`s and problem size, or scalability. This paper also describes the parallel implementation and performance of the elliptic solver used in DANTSYS/MPI for solving the synthetic acceleration equations

A Bovine Pericardium Rigid Prosthesis For Left Ventricle Restoration: 12 Years Of Follow-up [prótese Rígida De Pericárdio Bovino Para Remodelamento Ventricular Esquerdo: 12 Anos De Seguimento]

Background: Myocardial infarction might result in dilated left ventricle and numerous techniques have been described to restore the original left ventricle shape and identify tools for late survival assessment. The aim of this study is to compare our experience with a modified Dor procedure using a rigid prosthesis to the septal anterior ventricular exclusion procedure (SAVE) for left ventricle restoration. The EuroScore index for prediction of late follow up survival was evaluated. Methods: We evaluated 80 patients who underwent left ventricle restoration between 1999 to 2007 and eight patients were excluded with incomplete data. A modified Dor procedure with rigid prosthesis (MD group) was performed on 53 patients and 19 underwent the septal anterior ventricular exclusion procedure (SAVE group). The patients were classified according their left ventricle shape as type I, II or III. Kaplan-Meier and Cox proportional hazard ratio regressions analysis were performed to assess survival after both techniques and expected surgical mortality using EuroScore index ranking after 12 years of follow up. Results: The operative mortality was comparable in both groups ranked by EuroScore index. The groups were comparable for all clinical data, except the MD group had more patients using intra-aortic balloon pumps before surgery, (5.7% vs. 0; P<0.01). Kaplan Meier analysis by left ventricle shape showed comparable survival for all patients, with slightly higher survival for type I. Kaplan Meier analysis of all death showed equivalent survival curves for both techniques after 12 years of follow up (71.5 ± 12.3 vs. 46.6 ±20.5 years; P=0.08). Kaplan Meier analysis of EuroScore index for all patients showed a difference between the three ranked categories, i.e., 0 to 10%, 11 to 49% and higher than 50% expected surgical mortality after 12 years of follow up (70.9 ± 16.2 vs. 67.5 ± 12.7 vs. 53.0 ± 15.5; P=0.003). Conclusion: The MD procedure showed consistent ejection fraction improvements after long term follow up. Survival was comparable for all ventricular types and for the MD and SAVE procedures. The EuroScore index is a useful index for late survival assessment of ventricular restoration techniques.262164172Cooley, D.A., Hallman, G.L., Henly, W.S., Left ventricular aneurysm due to myocardial infarctionexperience with 37 patients undergoing aneurysmectomy (1964) Arch Surg, 88, pp. 114-121Jatene, A.D., Left ventricular aneurysmectomy. Resection or reconstruction (1985) J Thorac Cardiovasc Surg, 89 (3), pp. 321-331Dor, V., Saab, M., Coste, P., Kornaszewska, M., Montiglio, F., Left ventricular aneurysm: A new surgical approach (1989) Thorac Cardiovasc Surg, 37 (1), pp. 11-19Dor, V., Sabatier, M., di Donato, M., Montiglio, F., Toso, A., Maioli, M., Efficacy of endoventricular patch plasty in large postinfarction akinetic scar and severe left ventricular dysfunction: Comparison with a series of large dyskinetic scars (1998) J Thorac Cardiovasc Surg, 116 (1), pp. 50-59Braile, D.M., Mustafa, R.M., Ardito, R.V., Zaiantchick, M., Coelho, W.M., (1991) Correction of the Left Ventricle Geometry with Semi Rigid Bovine Pericardial Prosthesis Rev Bras Cir Cardiovasc, 6 (2), pp. 109-115Isomura, T., Horii, T., Suma, H., Buckberg, G.D., Septal anterior ventricular exclusion operation (Pacopexy) for ischemic dilated cardiomyopathy: Treat form not disease (2006) Eur J Cardiothorac Surg, 29 (SUPPL. 1), pp. S245-S250. , RESTORE GroupJones, R.H., Velazquez, E.J., Michler, R.E., Sopko, G., Oh, J.K., O'Connor, C.M., Coronary bypass surgery with or without surgical ventricular reconstruction (2009) N Engl J Med, 360 (17), pp. 1705-1717di Donato, M., Castelvecchio, S., Kukulski, T., Bussadori, C., Giacomazzi, F., Frigiola, A., Surgical ventricular restoration: Left ventricular shape influence on cardiac function, clinical status, and survival (2009) Ann Thorac Surg, 87 (2), pp. 455-461Najafi, M., Sheikhvatan, M., Montazeri, A., Sheikhfathollahi, M., Predictors of quality of life among patients undergoing coronary artery bypass surgery (2008) Acta Cardiol, 63 (6), pp. 713-721Messaoudi, N., de Cocker, J., Stockman, B.A., Bossaert, L.L., Rodrigus, I.E., Is EuroSCORE useful in the prediction of extended intensive care unit stay after cardiac surgery? (2009) Eur J Cardiothorac Surg, 36 (1), pp. 35-39Santarpino, G., Onorati, F., Rubino, A.S., Abdalla, K., Caroleo, S., Santangelo, E., Preoperative intraaortic balloon pumping improves outcomes for high-risk patients in routine coronary artery bypass graft surgery (2009) Ann Thorac Surg, 87 (2), pp. 481-488Nashef, S.A., Roques, F., Michel, P., Gauducheau, E., Lemeshow, S., Salamon, R., European system for cardiac operative risk evaluation (EuroSCORE) (1999) Eur J Cardiothorac Surg, 16 (1), pp. 9-13Dor, V., Sabatier, M., di Donato, M., Maioli, M., Toso, A., Montiglio, F., Late hemodynamic results after left ventricular patch repair associated with coronary grafting in patients with postinfarction akinetic or dyskinetic aneurysm of the left ventricle (1995) J Thorac Cardiovasc Surg, 110 (5), pp. 1291-1299Athanasuleas, C.L., Buckberg, G.D., Stanley, A.W., Siler, W., Dor, V., Didonato, M., RESTORE Group. Surgical ventricular restoration: The RESTORE Group experience (2004) Heart Fail Rev, 9 (4), pp. 287-297Salati, M., di Biasi, P., Paje, A., Santoli, C., Left ventricular geometry after endoventriculoplasty (1993) Eur J Cardiothorac Surg, 7 (11), pp. 574-578Buckberg, G.D., Coghlan, H.C., Torrent-Guasp, F., The structure and function of the helical heart and its buttress wrapping. VI. Geometric Concepts of Heart Failure and Use For Structural Correction (2001) Semin Thorac Cardiovasc Surg, 13 (4), pp. 386-401di Donato, M., Sabatier, M., Dor, V., Gensini, G.F., Toso, A., Maioli, M., Effects of the Dor procedure on left ventricular dimension and shape and geometric correlates of mitral regurgitation one year after surgery (2001) J Thorac Cardiovasc Surg, 121 (1), pp. 91-96Suma, H., Horii, T., Isomura, T., Buckberg, G., A new concept of ventricular restoration for nonischemic dilated cardiomyopathy (2006) Eur J Cardiothorac Surg, 29 (SUPPL. 1), pp. S207-S212. , RESTORE GroupForm versus disease: Optimizing geometry during ventricular restoration (2006) Eur J Cardiothorac Surg, 29 (SUPPL. 1), pp. S238-S244. , RESTORE GroupKieser, T.M., The left ventricle: To reconstruct or not: Lessons from the STICH trial (2009) J Thorac Cardiovasc Surg, 138 (3), p. 784Suma, H., Isomura, T., Horii, T., Buckberg, G., Role of site selection for left ventriculoplasty to treat idiopathic dilated cardiomyopathy (2004) Heart Fail Rev, 9 (4), pp. 329-336. , RESTORE GroupDancini, J.L., Rodrigues, J.J., Santos, J.S., Pinto, R.F.A., Burgos, F.J.C., Conforti, C.A., Left ventricular aneurysmectomy: Late followup (1996) Rev Bras Cir Cardiovasc, 1 (11), pp. 23-29Almeida, R.M.S., Lima, J.D., Bastos, L.C., Carvalho, C.T., Loures, D.R., Endoventricular circular patch plasty with septal exclusion: Initial experience (2000) Rev Bras Cir Cardiovasc, 4 (15), pp. 302-307Campagnucci, V.P., Rivetti, L.A., Pinto e Silva, A.M.R., Gandra, S.M.A., Pereira, W.L., Aneurismectomia de ventrículo esquerdo com o coração batendo ininterruptamente: Resultados imediatos (2006) Rev Bras Cir Cardiovasc, 21 (1), pp. 55-61Herrera, C.B., Insalralde, A., Brandi, A.C., Santos, C.A., Herrera, D.D., Soares, M.J.F., Correção de aneurisma de ventrículo esquerdo em paciente chagásico empregando prótese de pericárdio bovino (2000) Rev Bras Cir Cardiovasc, 15 (1), pp. 72-74Sgarbi, C.J., Ardito, R.V., Santos, R.C., Bogdan, R.A.B., Arruda Jr., F.V., Silva, E.M., Correção cirúrgica do aneurisma de ventrículo esquerdo: Comparação entre as técnicas de sutura linear e reconstrução geométrica (2000) Rev Bras Cir Cardiovasc, 15 (4), pp. 293-301Versteegh, M.I., Lamb, H.J., Bax, J.J., Curiel, F.B., van der Wall, E.E., de Roos, A., MRI evaluation of left ventricular function in anterior LV aneurysms before and after surgical resection (2003) Eur J Cardiothorac Surg, 23 (4), pp. 609-613Use of cardiac magnetic resonance imaging in surgical ventricular restoration (2006) Eur J Cardiothorac Surg, 29 (SUPPL. 1), pp. S216-S224. , Buckberg GD;RESTORE GroupWalker, J.C., Guccione, J.M., Jiang, Y., Zhang, P., Wallace, A.W., Hsu, E.W., Helical myofiber orientation after myocardial infarction and left ventricular surgical restoration in sheep (2005) J Thorac Cardiovasc Surg, 129 (2), pp. 382-39

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target

Bayesian Nonparametric Inverse Reinforcement Learning

Inverse reinforcement learning (IRL) is the task of learning the reward function of a Markov Decision Process (MDP) given the transition function and a set of observed demonstrations in the form of state-action pairs. Current IRL algorithms attempt to find a single reward function which explains the entire observation set. In practice, this leads to a computationally-costly search over a large (typically infinite) space of complex reward functions. This paper proposes the notion that if the observations can be partitioned into smaller groups, a class of much simpler reward functions can be used to explain each group. The proposed method uses a Bayesian nonparametric mixture model to automatically partition the data and find a set of simple reward functions corresponding to each partition. The simple rewards are interpreted intuitively as subgoals, which can be used to predict actions or analyze which states are important to the demonstrator. Experimental results are given for simple examples showing comparable performance to other IRL algorithms in nominal situations. Moreover, the proposed method handles cyclic tasks (where the agent begins and ends in the same state) that would break existing algorithms without modification. Finally, the new algorithm has a fundamentally different structure than previous methods, making it more computationally efficient in a real-world learning scenario where the state space is large but the demonstration set is small

Molecular Dynamics Study of Bamboo-like Carbon Nanotube Nucleation

MD simulations based on an empirical potential energy surface were used to study the nucleation of bamboo-like carbon nanotubes (BCNTs). The simulations reveal that inner walls of the bamboo structure start to nucleate at the junction between the outer nanotube wall and the catalyst particle. In agreement with experimental results, the simulations show that BCNTs nucleate at higher dissolved carbon concentrations (i.e., feedstock pressures) than those where non-bamboolike carbon nanotubes are nucleated