A transferable artificial neural network model for atomic forces in nanoparticles

We have designed a new method to fit the energy and atomic forces using a single artificial neural network (SANN) for any number of chemical species present in a molecular system. The traditional approach for fitting the potential energy surface (PES) for a multicomponent (MC) system using artificial neural network (ANN) is to consider n number of networks for n number of chemical species in the system. This shoots the computational cost and makes it difficult to apply to a system containing more number of species. We present a new strategy of using a SANN to compute energy and forces of a chemical system. Since, atomic forces are significant for geometry optimizations and molecular dynamics simulations (MDS) for any chemical system, their accurate prediction is of utmost importance. So, to predict the atomic forces, we have modified the traditional way of fitting forces from underlying energy expression. We have applied our strategy to study geometry optimizations and dynamics in gold-silver nanoalloys and thiol protected gold nanoclusters. Also, force fitting has made it possible to train smaller size systems and extrapolate the parameters to make accurate predictions for larger systems. This proposed strategy has definitely made the mapping and fitting of atomic forces easier and can be applied to a wide variety of molecular systems

Persistence of Randomly Coupled Fluctuating Interfaces

We study the persistence properties in a simple model of two coupled interfaces characterized by heights h_1 and h_2 respectively, each growing over a d-dimensional substrate. The first interface evolves independently of the second and can correspond to any generic growing interface, e.g., of the Edwards-Wilkinson or of the Kardar-Parisi-Zhang variety. The evolution of h_2, however, is coupled to h_1 via a quenched random velocity field. In the limit d\to 0, our model reduces to the Matheron-de Marsily model in two dimensions. For d=1, our model describes a Rouse polymer chain in two dimensions advected by a transverse velocity field. We show analytically that after a long waiting time t_0\to \infty, the stochastic process h_2, at a fixed point in space but as a function of time, becomes a fractional Brownian motion with a Hurst exponent, H_2=1-\beta_1/2, where \beta_1 is the growth exponent characterizing the first interface. The associated persistence exponent is shown to be \theta_s^2=1-H_2=\beta_1/2. These analytical results are verified by numerical simulations.Comment: 15 pages, 3 .eps figures include

Extreme Value Statistics of Hierarchically Correlated Variables: Deviation from Gumbel Statistics and Anomalous Persistence

We study analytically the distribution of the minimum of a set of hierarchically correlated random variables $E_1$, $E_2$, $...$, $E_N$ where $E_i$ represents the energy of the $i$-th path of a directed polymer on a Cayley tree. If the variables were uncorrelated, the minimum energy would have an asymptotic Gumbel distribution. We show that due to the hierarchical correlations, the forward tail of the distribution of the minimum energy becomes highly nnon universal, depends explicitly on the distribution of the bond energies $\epsilon$ and is generically different from the super-exponential forward tail of the Gumbel distribution. The consequence of these results to the persistence of hierarchically correlated random variables is discussed and the persistence is also shown to be generically anomalous.Comment: 6 pages, 5 figures ep

The longest excursion of stochastic processes in nonequilibrium systems

We consider the excursions, i.e. the intervals between consecutive zeros, of stochastic processes that arise in a variety of nonequilibrium systems and study the temporal growth of the longest one l_{\max}(t) up to time t. For smooth processes, we find a universal linear growth \simeq Q_{\infty} t with a model dependent amplitude Q_\infty. In contrast, for non-smooth processes with a persistence exponent \theta, we show that < l_{\max}(t) > has a linear growth if \theta \sim t^{1-\psi} if \theta > \theta_c. The amplitude Q_{\infty} and the exponent \psi are novel quantities associated to nonequilibrium dynamics. These behaviors are obtained by exact analytical calculations for renewal and multiplicative processes and numerical simulations for other systems such as the coarsening dynamics in Ising model as well as the diffusion equation with random initial conditions.Comment: 4 pages,2 figure

On the landing of spinner dolphin Stenella longirostris at Lawson's Bay, Visakhapatnam

Three adult spinner dolphins were caught by mechanised, fibre-glass, beach landing craft and landed at Lawson's Bay on 19-4-'93 They were caught off RushikondalO km from Visakhapatnam at a depth of 15 metres

Poverty Assessment in Rural Area of Jodhpur District in Western Arid Region of Rajasthan

An attempt has been made to assess the poverty status in rural area of Jodhpur district of western Rajasthan. Two villages were randomly selected fall in the radius of 20 km from the Jodhpur city whereas another two villages were selected 60 km far from Jodhpur city with poor infrastructure facility and poor non-farm employment. 30 respondents were randomly selected from each selected village.A total of 120 respondents were selected from four village for the study. Simple tabulation method was used. For determining the poverty status, income method was used. From the study, it is revealed that agriculture, livestock, non-farm-labor activities are the main factor for poverty assessment. Size of land holding is a crucial factor. Marginal and small land holding couple with low income, are the main reason for poverty. The percentage of earners in the family size groups and percentage of dependents is inversely proportionate

Mengenalkan Anak Pada Dunia Film

According to research conducted by Yayasan Kesejahteraan Anak Indonesia (Indonesian Children Wealth Foundation—YKAI), children spent their times in front of TV more than 20-25 hours/week, or 3-4 hours/day. Another research stated that children viewing habit reached a relatively high exposure. Based on these facts, this article speaks about the importance to teach children how to appreciate lesson films and other audiovisuals. The process included several steps, such as an introduction to the duty and responsibility of media worker or film maker toward their masterpiece and their audience, reading critics and reference to reduce disappointment if someone meets an underdeveloped or low quality film

Poverty Assessment in Urban Area of Jodhpur District in Western Arid Region of Rajasthan

An attempt has been made to assess the poverty status in rural area of Jodhpur district of western Rajasthan. Two villages were randomly selected fall in the radius of 20 km from the Jodhpur city whereas another two villages were selected 60 km far from Jodhpur city with poor infrastructure facility and poor non-farm employment. 30 respondents were randomly selected from each selected village.A total of 120 respondents were selected from four village for the study. Simple tabulation method was used. For determining the poverty status, income method was used. From the study, it is revealed that agriculture, livestock, non-farm-labor activities are the main factor for poverty assessment. Size of land holding is a crucial factor. Marginal and small land holding couple with low income, are the main reason for poverty. The percentage of earners in the family size groups and percentage of dependents is inversely proportionate

Persistence in nonequilibrium surface growth

Persistence probabilities of the interface height in (1+1)- and (2+1)-dimensional atomistic, solid-on-solid, stochastic models of surface growth are studied using kinetic Monte Carlo simulations, with emphasis on models that belong to the molecular beam epitaxy (MBE) universality class. Both the initial transient and the long-time steady-state regimes are investigated. We show that for growth models in the MBE universality class, the nonlinearity of the underlying dynamical equation is clearly reflected in the difference between the measured values of the positive and negative persistence exponents in both transient and steady-state regimes. For the MBE universality class, the positive and negative persistence exponents in the steady-state are found to be $\theta^S_{+} = 0.66 \pm 0.02$ and $\theta^S_{-} = 0.78 \pm 0.02$, respectively, in (1+1) dimensions, and $\theta^S_{+} = 0.76 \pm 0.02$ and $\theta^S_{-} =0.85 \pm 0.02$, respectively, in (2+1) dimensions. The noise reduction technique is applied on some of the (1+1)-dimensional models in order to obtain accurate values of the persistence exponents. We show analytically that a relation between the steady-state persistence exponent and the dynamic growth exponent, found earlier to be valid for linear models, should be satisfied by the smaller of the two steady-state persistence exponents in the nonlinear models. Our numerical results for the persistence exponents are consistent with this prediction. We also find that the steady-state persistence exponents can be obtained from simulations over times that are much shorter than that required for the interface to reach the steady state. The dependence of the persistence probability on the system size and the sampling time is shown to be described by a simple scaling form.Comment: 28 pages, 16 figure