Real-time dynamics of clusters. III. I_2Ne_n (n=2–4), picosecond fragmentation, and evaporation

In this paper (III) we report real-time studies of the picosecond dynamics of iodine in Ne clusters I*2Nen(n = 2–4) --> I*2 + nNe. The results are discussed in relation to vibrational predissociation (VP), basic to the I2X systems, and to the onset of intramolecular vibrational-energy redistribution (IVR). The latter process, which is a precursor for the evaporation of the host atoms or for further fragmentation, is found to be increasingly effective as the cluster size increases; low-energy van der Waals modes act as the accepting (bath) modes. The reaction dynamics for I2Ne2 are examined and quantitatively compared to a simple model which describes the dynamics as consecutive bond breaking. On this basis, it is concluded that the onset of energy redistribution is observed in I2Ne2. Comparison of I2Ne and I2Ne2 to larger clusters (n=3,4) is accomplished by introducing an overall effective reaction rate. From measurements of the rates and their dependence on v[script ']i, the initial quantum number of the I2 stretch, we are able to examine the dynamics of direct fragmentation and evaporation, and compare with theory

Towards A Generic, Service-Oriented Framework for Distributed Real-Time Systems

REACTION 2012. 1st International workshop on Real-time and distributed computing in emerging applications. December 4th, 2012, San Juan, Puerto Rico.Continuously increasing complexity and scale of distributed real-time systems have exposed the limitations of their existing development methodologies. This fact is evident by the unsustainable rate of increase in the development and maintenance costs of such systems. In this paper, we present a generic, service-oriented framework for distributed real-time systems. The proposed framework can potentially serve as the basis for a widely applicable, cross-domain toolset, thus, decreasing the development and maintenance costs for distributed real-time systems. The proposed framework consists of a generic, service-oriented deployment platform that abstracts away the details of implementation platform and an associated development methodology. The proposed framework makes extensive use of the existing service-oriented technologies such as Web Services. However, it also extends these technologies for application to distributed real-time systems by introducing QoS-aware service deployment and service monitoring phases. This paper presents the details of the proposed framework as well as a case-study of the application of the proposed framework to the domain of smart gri

Studies on chemoviscosity modeling for thermosetting resins

A new analytical model for simulating chemoviscosity of thermosetting resins has been formulated. The model is developed by modifying the well-established Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By introducing a relationship between the glass transition temperature Tg(t) and the degree of cure alpha(t) of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature dependent functions of the modified WLF theory constants C sub 1 (t) and C sub 2 (t) were determined from the isothermal cure data. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data. This work represents progress toward establishing a chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformation of the thermosetting resin systems during cure

Chemoviscosity modeling for thermosetting resin systems, part 3

A new analytical model for simulating chemoviscosity resin has been formulated. The model is developed by modifying the well established Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By introducing a relationship between the glass transition temperature (T sub g (t)) and the degree of cure alpha(t) of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature-dependent functions of the modified WLF theory parameters C sub 1 (T) and C sub 2 (T) were determined from the isothermal cure data. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data. This work represents a progress toward establishing a chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformations of the thermosetting resin systems during cure

Noise from spatial heterogeneity changes signal amplification magnitude and increases the variability in dose responses

In most molecular level simulations, spatial heterogeneity is neglected by the well-mixed condition assumption. However, the signals of biomolecular networks are affected from both time and space, which are responsible for diverse physiological responses. To account the spatial heterogeneity in the kinetic model, we consider multiple subvolumes of a reaction, introduce parameters representing transfer of ligands between the volumes, and reduce this to an error-term representing the difference between the well-mixed condition and the actual spatial factors. The error-term approach allows modelling of varying spatial heterogeneity without increasing computational burden exponentially. The effect of varying this term, d, between 0 (well-mixed) and 1 (no mixing) and of adding noise to the kinetic constants was then investigated and correlated with knowledge of the behaviour of real systems and situations where network models are inadequate. The spatial distribution effects on the epidermal growth factor receptor (EGFR) in human mammary epithelial tissue, which is involved in proliferation and tumorigenesis, are studied by introducing noisy kinetic constants. The steady-state of the dose response in the EGFR is strongly affected by spatial fluctuations. The ligand-bound receptor is reduced up to 50% from the response without spatial fluctuations and the variance of the steady-state is increased at least 2-fold from the one for no spatial fluctuations. On the other hand, dynamic properties such as the rising time and overshoot are less sensitive to spatial noise

The Effects of Realistic Nuclear Kinetics, Dimensionality, and Resolution on Detonations in Low-Density Type Ia Supernovae Environments

Type Ia supernovae are most likely thermonuclear explosions of carbon/oxygen white dwarves in binary stellar systems. These events contribute to the chemical and dynamical evolution of their host galaxies and are essential to our understanding of the evolution of our universe through their use as cosmological distance indicators. Nearly all of the currently favored explosion scenarios for these supernovae involve detonations. However, modeling astrophysical detonations can be complicated by numerical effects related to grid resolution. In addition, the fidelity of the reaction network chosen to evolve the nuclear burning can alter the time and length scales over which the burning occurs. Multidimensional effects further complicate matters by introducing a complex cellular structure within the reaction zone. Here, we report on how these complications can affect the outcome of simulating such astrophysical detonations in the context of Type Ia supernovae