Growth dynamics of scholarly and scientific journals

Results are presented on journal growth dynamics at both the micro and macro levels, showingthat journal development clearly follows researcher behaviour and growth characteristics. At thesubject discipline level, the journal system is highly responsive to research events. Overall journalgrowth characteristics clearly show the predominance of 3.3% compound annual growth under anumber of different socio-political climates. It is proposed that this represents a lower limit tojournal growth rates and that this growth is the outcome of a self-organizing information systemthat reflects on the growth and specialization of knowledge. Potential models are suggested whichcould form attractive theoretical further lines of enquiry.     

Emulating Neuromorphic and In-Memory Computing Utilizing Defect Engineering in 2D-Layered WSeOx and WSe2 Thin Films by Plasma-Assisted Selenization Process

The neuromorphic and in-memory computing using memristors are promising for the building of the next generation computing systems. However, the diffusion dynamics of metal ions/atoms inside the switching medium impose variability in conducting filament (CF) formation, thus limiting their use in von-Neumann architecture. The precise modulation on the diffusion of metal ions/atoms and their reduction/oxidation probability holds promise to overcome the speed, size, and energy issues of present-day computers. Here, this study shows that the diffusion of metal ions can be modulated by defects inside the switching medium and confines metal filaments in a precise 1D channel. This filament confinement by the defect engineering leads to an anomalous switching mechanism with two interchangeable modes: unipolar threshold and bipolar modes. The variation between two modes can be modulated by controlling defects in the structures, leading to a uniform switching with low SET/RESET voltage variations of 17.3% and −17.6%, respectively. Moreover, the convolutional neural network is implemented to emulate synaptic plasticity and image recognition to achieve recognition accuracy of 87% due to a highly linear weight update, demonstrating its potential for in-memory computing.     

Interpenetrating polymer networks from castor oil based polyurethane and poly(methyl methacrylate), III

Liquid prepolyurethanes (PPU) were obtained from castor oil and toluene-2,4-diisocyanate under different experimental conditions varying NCO/OH ratio. All these prepolyurethanes were subsequently interpenetrating with poly(methyl methacrylate) made by radical polymerization initiated with benzoyl peroxide. The novel PPU/PMMA interpenetrating polymer networks were obtained as though films by transfer moulding. They were characterized by thermal studies (DSC and TGA) and mechanical properties viz., tensile strength, modulus of elasticity, and percent elongation at break. The morphological behaviour was analyzed by scanning electron microscopy.     

L-Arginine and Nitric Oxide in CNS Function and Neurodegenerative Diseases

One of the main functions of L-arginine (ARG) is the synthesis of nitric oxide (NO). NO is an important regulator of physiological processes in the central nervous system (CNS). NO promotes optimal cerebral blood flow, consolidates memory processes, facilitates long-term potentiation, maintains sleep-wake cycles, and assists in normal olfaction. However, at pathological levels, NO adversely affects brain function producing nitroxidative stress and promoting development of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and other disorders of the CNS. This review summarizes current knowledge of the role of NO in the CNS and the role of diet in regulating the levels of NO.     

A combinatorial algorithm for max csp

We consider the problem max csp over multi-valued domains with variables ranging over sets of size s_i?s and constraints involving k_j?k variables. We study two algorithms with approximation ratios A and B, respectively, so we obtain a solution with approximation ratio max(A,B).The first algorithm is based on the linear programming algorithm of Serna, Trevisan, and Xhafa [Proc. 15th Annual Symp. on Theoret. Aspects of Comput. Sci., 1998, pp. 488-498] and gives ratio A which is bounded below by s^1−k. For k=2, our bound in terms of the individual set sizes is the minimum over all constraints involving two variables of , where s₁ and s₂ are the set sizes for the two variables.We then give a simple combinatorial algorithm which has approximation ratio B, with B>A/e. The bound is greater than s^1−k/e in general, and greater than s^1−k(1−(s−1)/2(k−1)) for s?k−1, thus close to the s^1−k linear programming bound for large k. For k=2, the bound is if s=2, 1/2(s−1) if s?3, and in general greater than the minimum of 1/4s₁+1/4s₂ over constraints with set sizes s₁ and s₂, thus within a factor of two of the linear programming bound.For the case of k=2 and s=2 we prove an integrality gap of . This shows that our analysis is tight for any method that uses the linear programming upper bound.     

Synthesis and characterization of some polyurethanes

Polymers containing urethane units were synthesized by solution polymerization of bisphenols A, C, and F with diisocyanates viz. toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate, respectively. Thus obtained polymers were pale yellow amorphous powders. These polymers were characterized by infrared spectral studies and nitrogen content. The number-average molecular weights (M?_n) were estimated from conductometric titration and limiting viscosity number [η] in dimethyl formamide. From thermogravimetric analyses, the thermal behaviour was studied. Kinetic parameters for their degradation were computed.     

Interpenetrating polymer networks from castor oil based polyurethanes and poly(ethyl acrylate)

Polyurethanes were obtained by the reaction of hydroxyl groups of castor oil with hexamethylene diisocyanate, isophorone diisocyanate or diphenylmethane diisocyanate using an NCO/OH ratio of 1.6. These polyurethanes were swollen in ethyl acrylate monomer and subsequently polymerized by radical polymerization initiated with benzoyl peroxide in the presence of the crosslinking agent ethylene glycol dimethacrylate. A series of interpenetrating polymer networks (PU/PEA IPNs) were obtained as tough films by casting in glass moulds. The characteristics of these films were determined: resistance to chemical reagents, thermal behaviour (DSC, TGA), tensile strength, Young's modulus, elongation at break (%) and Shore A hardness. The morphology was determined by scanning electron microscopy, and the dielectric properties such as electrical conductivity, dielectric constant (ε′), dielectric loss (ε″) and loss tangent (tan δ) were studied.     

Continuous elliptic and multi-dimensional hyperbolic Darcy-flux finite-volume methods

Elliptic and hyperbolic Darcy-flux approximations are presented. Families of flux-continuous finite-volume methods are investigated for the elliptic full-tensor pressure equation with general discontinuous coefficients. Full pressure continuity across control-volume interfaces is built into the methods leading to an important distinction from the earlier pointwise continuous methods. The families of quasi-positive methods significantly reduce spurious oscillations (induced by earlier schemes) in discrete pressure solutions for strongly anisotropic full-tensor fields. Anisotropy favoring triangulation and non-linear flux splitting are also shown to be effective for computing solutions free of spurious oscillations.Multi-dimensional upwind schemes that reduce cross-wind numerical diffusion induced by the standard upwind scheme are also presented for hyperbolic Darcy-flux approximation.     

Versatile platform for creating gradient combinatorial libraries via modulated light exposure

This article details the design, construction, and operation of flexible system that modulates light exposure for the purpose of fabricating continuous and discrete gradient combinatorial libraries. Designed for versatility, the device combines "off the shelf" components, modular accessories, and flexible computer control, so that it can be used for a variety of combinatorial research applications. Salient aspects and capabilities of the instrument are illustrated through two practical examples. The first case demonstrates how user defined exposure functions can be used to create continuous surface energy gradient libraries with a linear profile. The second example illustrates the creation of continuous and discrete libraries for mapping exposure-property functions in a photocurable polymer system.