91 research outputs found
Scalar soliton quantization with generic moduli
No full textThis article is distributed under the terms of the Creative Commons
Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in
any medium, provided the original author(s) and source are credArticle funded by SCOAP3. CP is
a Royal Society Research Fellow and partly supported by the U.S. Department of Energy
under grants DOE-SC0010008, DOE-ARRA-SC0003883 and DOE-DE-SC0007897. ABR
is supported by the Mitchell Family Foundation. We would like to thank the Mitchell
Institute at Texas A&M and the NHETC at Rutgers University respectively for hospitality
during the course of this work. We would also like to acknowledge the Aspen Center
for Physics and NSF grant 1066293 for a stimulating research environment which led to
questions addressed in this paper
Recombinant ADAMTS13 normalizes von Willebrand factor-cleaving activity in plasma of acquired TTP patients by overriding inhibitory antibodies
No full textSevere deficiency of the von Willebrand factor (VWF)-cleaving protease ADAMTS13 as observed in acquired thrombotic thrombocytopenic purpura (TTP) is caused by inhibitory and non-inhibitory autoantibodies directed against the protease. Current treatment with plasma exchange is considered to remove circulating antibodies and to concurrently replenish the deficient enzyme
The domain wall soliton’s tension
No full textAbstract We calculate the one-loop tension of the domain wall soliton in the ϕ 4 double-well model. Our result agrees with previous results from Dashen, Hasslacher and Neveu (1974) in 1 + 1d and Jaimunga, Semenoff and Zarembo (1999) in 2 + 1d. After an additional 25 year interval, we have obtained a one-loop tension correction of 0.0410959 m 3 in 3 + 1d. In this case, unlike lower-dimensional cases, even after normal ordering there are ultraviolet divergences that require both mass and also coupling constant renormalization. We renormalized the coupling so that the three-point interaction in the effective potential is given by its tree level value at zero external momenta
Desenvolvimento de modelos de gás em rede para escoamentos monofásicos e bifásicos
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Este trabalho divide-se em duas partes, na primeira parte é apresentado um método para determinação de permeabilidade intrínseca baseado em modelos de gás em rede. Mostra-se que estes modelos possuem um comportamento que pode ser descrito pelas equações de Navier-Stokes para baixo número de Mach. O método foi utilizado para determinação de permeabilidade de rochas de reservatório petrolíferos e os resultados comparados com dados experimentais. Também na primeira parte é apresentado o modelo de rede BGK (Lattice Boltzmann). Baseado na equação de Boltzmann este método permite a integração numérica da equação de Navier-Stokes. São apresentados resultados para escoamentos em uma cavidade quadrada e também a formação das esteiras de vórtices de von-Karman. Na segunda parte, é proposto um novo modelo para a simulação de fluidos imiscíveis baseado na idéia de um campo de mediadores que simulam interações a longa distância utilizando regras locais. Este modelo permite, além disso, o controle da tensão interfacial e da espessura da interface. A dinâmica do modelo é descrita e são apresentados resultados de simulações de diversos casos, incluindo a verificação da lei de Laplace, o fenômeno de coalescência, interações de pares de fluidos molhante/não-molhante com superfícies sólidas e a formação de uma gota sob a ação da gravidade. Estes resultados são comparados com os dados disponíveis
Simulating Uniform Motion in Lattice Computers I: Constant Speed Particle Translation
No full textEuclidean n-space can be discretely represented as an n-dimensional lattice, and a mesh computer can be naturally associated with each (possibly finite) subset of such a lattice, where the processors are at the lattice points in the subset and the mesh's interconnections correspond to minimal length vectors between the lattice points associated with processors. An algorithm template is presented for analogical simulation, in such mesh computers, of constant speed, particle motion in euclidean n-space, and a particular instance of the template is refined for constant speed straight-line particle translation. Discussed are the possibilities of using this algorithm for simulating constant speed solid body motion and the possible utility of this algorithm for circumventing, in a new way, the difficulties, pointed out by Frisch and Hasslacher, in simulating 3-dimensional fluid flow in lattice gas cellular automata
Renal effects of levosimendan: a consensus report.
No full textRenal dysfunction is common in clinical settings in which cardiac function is compromised such as heart failure, cardiac surgery or sepsis, and is associated with high morbidity and mortality. Levosimendan is a calcium sensitizer and potassium channel opener used in the treatment of acute heart failure. This review describes the effects of the inodilator levosimendan on renal function. A panel of 25 scientists and clinicians from 15 European countries (Austria, Finland, France, Hungary, Germany, Greece, Italy, Portugal, the Netherlands, Slovenia, Spain, Sweden, Turkey, the United Kingdom, and Ukraine) convened and reached a consensus on the current interpretation of the renal effects of levosimendan described both in non-clinical research and in clinical study reports. Most reports on the effect of levosimendan indicate an improvement of renal function in heart failure, sepsis and cardiac surgery settings. However, caution should be applied as study designs differed from randomized, controlled studies to uncontrolled ones. Importantly, in the largest HF study (REVIVE I and II) no significant changes in the renal function were detected. As it regards the mechanism of action, the opening of mitochondrial KATP channels by levosimendan is involved through a preconditioning effect. There is a strong rationale for randomized controlled trials seeking beneficial renal effects of levosimendan. As an example, a study is shortly to commence to assess the role of levosimendan for the prevention of acute organ dysfunction in sepsis
Energy levels of interacting fields in a box
No full textWe study the influence of boundary conditions on energy levels of interacting fields in a box and discuss some consequences when we change the size of the box. In order to do this we calculate the energy levels of bound states of a scalar massive field chi interacting with another scalar field phi through the Lagrangian L-int = 3/2 g phi(2)chi(2) in a one-dimensional box on which we impose Dirichlet boundary conditions. We find that the gap between the bound states changes with the size of the box in a nontrivial way. For the case where the masses of the two fields are equal and for large box the energy levels of Dashen-Hasslacher-Neveu (DHN model) are recovered and we have a kind of boson condensate for the ground state. Below a critical box size L similar to 2.93 (2 root 2 /M) the ground-state level splits, which we interpret as particle-antiparticle production under small perturbations of box size. Below other critical sizes, L similar to (6/10)(2 root 2 /M) and L similar to 1.71 (2 root 2 /M), of the box, the ground state and first excited state merge in the continuum part of the spectrum.3882185219
On breathers in affine toda theories
No full textOscillating solitonic solutions, the breathers, of affine Toda theory are studied. These breather solutions are constructed from two solitons of the same mass with velocity opposite of each other; by analytically continuing its velocity or rapidity to a complex value, the resulting solution becomes a periodic solution. Generally, the parameters in the soliton solutions are restricted to a certain range of definition. In particular, it is shown for a(^(1))(_n) and d(^(1))(_4) cases, these restrictions can be calculated explicitly. To some cases of a(^(a))(_n) theories, one can show that there are sine-Gordon embedded solitons which give rise to a sine-Gordon breather. Furthermore, these breather solutions carry topological charges. These topological charges are calculated and it is found that they are exactly the same as the topological charges of some single soliton cases. Moreover, for the non-zero topological charges, one can show they belong to the irreducible fundamental representation component of the tensor product of two fundamental representations associated with the constituent solitons. This Clebsch-Gordan decomposition property is in agreement with the fusing rule of soliton which in turn is similar to the fusing rule of the fundamental Toda particles. One can also make a conjecture that the zero topological charge is always carried by a breather whose constituent solitons are associated with either conjugate or self-conjugate fundamental representations. Although it is not possible to know the individual topological charge carried by the constituent solitons in a breather, nevertheless using the crossing symmetry similar to that of the crossing symmetry of the S'-matrix, one can perform a superficial calculation to determine the constituent soliton's topological charges. Attempts to understand the exact scattering matrices of the sine-Gordon solitons and breathers from a root space point of . view is also discussed. This study tries to mimic the exact S-matrix construction of the real coupling regime affine Toda theory from the root space by Dorey. In this study, one replaces the ordinary Coxeter element, which plays an important role in the real coupling regime, with other transformations to incorporate the infinite product nature of the sine-Gordon soliton scattering matrix. However, the desired consistent construction seems to elude the author in this study
Coming Phase to Phase with Surfactants
No full textWe introduce a fast cellular automata model for the simulation of surfactant dynamics based on a previous model by Ono and Ikegami (2001). Here, individual lipid-like particles undergo stochastic movement and rotation on a two-dimensional lattice in response to potential energy gradients. The particles are endowed with an internal structure that reflects their amphiphilic character. Their head groups are weakly repelled by water whereas their hydrophobic tails cannot be readily hydrated. This leads to the formation of a variety of structures when the particles are placed in solution. The model in its current form compels a myriad of potential self-organisation experiments. Heterogeneous boundary conditions, chemical interactions and an arbitrary diversity of particles can easily be modelled. Our main objective was to establish a computational platform for investigating how mechanisms of lipid homeostasis might evolve among populations of protocells
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