ANALYSIS OF TIME-DELAYED NON-LINEAR EQUATIONS USING HF FUNCTIONS

The paper deals with the analysis of non-linear time delayed differential equations solved using HF functions. The analysis is first performed on Mackey-Glass Equation, which is a standard model for quantitative characterization of chaotic dynamics. The procedure is then performed on a generalized Human respiratory control model, where for different simulation parameters the analysis of Cheyne-Stokes Breathing is done. Both models are simulated in MATLAB. The graphs thus generated are used to provide suitable conclusions

Colossal electroresistance in ferromagnetic insulating state of single crystal Nd0.7_0.7Pb0.3_0.3MnO3_3

Colossal electroresistance (CER) has been observed in the ferromagnetic insulating (FMI) state of a manganite. Notably, the CER in the FMI state occurs in the absence of magnetoresistance (MR). Measurements of electroresistance (ER) and current induced resistivity switching have been performed in the ferromagnetic insulating state of a single crystal manganite of composition Nd$_0.7$Pb$_0.3$MnO$_3$ (NPMO30). The sample has a paramagnetic to ferromagnetic (Curie) transition temperature, Tc = 150 K and the ferromagnetic insulating state is realized for temperatures, T <~ 130 K. The colossal electroresistance, arising from a strongly nonlinear dependence of resistivity ($\rho$) on current density (j), attains a large value ($\approx 100$) in the ferromagnetic insulating state. The severity of this nonlinear behavior of resistivity at high current densities is progressively enhanced with decreasing temperature, resulting ultimately, in a regime of negative differential resistivity (NDR, d$\rho$/dj < 0) for temperatures <~ 25 K. Concomitant with the build-up of the ER however, is a collapse of the MR to a small value (< 20%) even in magnetic field, H = 7 T. This demonstrates that the mechanisms that give rise to ER and MR are effectively decoupled in the ferromagnetic insulating phase of manganites. We establish that, the behavior of ferromagnetic insulating phase is distinct from the ferromagnetic metallic (FMM) phase as well as the charge ordered insulating (COI) phase, which are the two commonly realized ground state phases of manganites.Comment: 24 pages (RevTeX4 preprint), 8 figures, submitted to PR

Critical properties of the double exchange ferromagnet Nd0.4Pb0.4MnO3

Results of a study of dc-magnetization M(T, H), performed on a Nd0.6Pb0.4MnO3 single crystal in the temperature range around T_C (Curie temperature) which embraces the critical region | epsilon | = |T -T_C |/T_C <= 0.05 are reported. The magnetic data analyzed in the critical region using the Kouvel-Fisher method give the values for the T_C =156.47 +/- 0.06 K and the critical exponents, beta = 0.374 +/- 0.006 (from the temperature dependence of magnetization), and gamma = 1.329 +/- 0.003 (from the temperature dependence of initial susceptibility). The critical isotherm M(T_C, H) gives delta = 4.547 +/- 0.1. Thus the scaling law gamma+beta=delta beta is fulfilled. The critical exponents obey the single scaling-equation of state M(H, epsilon) = epsilon^b f_+/- (H/epsilon^(beta + gamma)) where, f_+ for T > T_C and f_- for T< T_C. The exponent values are very close to those expected for the universality class of 3D Heisenberg ferromagnets with short-range interactions.Comment: 19 pages, including 6 figure

Electron paramagnetic resonance studies of the insulating ferromagnetic manganite Nd_0.8Pb_0.2MnO_3 above the transition temperature

Single crystals of Nd_{1-x}Pb_{x}MnO_{3} with x=0.2 are grown by high temperature solution growth technique using PbO-PbF_{2} flux. Magnetization studies on the samples show a transition to a ferromagnetic state below T_c ~ 125 K and the resistivity measurements show it to be an insulator throughout the temperature range 50 - 300 K. Electron Paramagnetic Resonance studies have been performed for T > T_{C} with a view to comparing the results with those on metallic ferromagnetic manganites. The temperature dependence of various parameters like g-value, linewidth and intensity has been studied in the temperature range 150 - 300 K. It is found that they behave in a manner similar to that exhibited by metallic ferromagnetic manganites.Comment: 8 pages, 4 figure

Chondrocyte Hypertrophy in Osteoarthritis: Mechanistic Studies and Models for the Identification of New Therapeutic Strategies

Articular cartilage shows limited self-healing ability owing to its low cellularity and avascularity. Untreated cartilage defects display an increased propensity to degenerate, leading to osteoarthritis (OA). During OA progression, articular chondrocytes are subjected to significant alterations in gene expression and phenotype, including a shift towards a hypertrophic-like state (with the expression of collagen type X, matrix metalloproteinases-13, and alkaline phosphatase) analogous to what eventuates during endochondral ossification. Present OA management strategies focus, however, exclusively on cartilage inflammation and degradation. A better understanding of the hypertrophic chondrocyte phenotype in OA might give new insights into its pathogenesis, suggesting potential disease-modifying therapeutic approaches. Recent developments in the field of cellular/molecular biology and tissue engineering proceeded in the direction of contrasting the onset of this hypertrophic phenotype, but knowledge gaps in the cause–effect of these processes are still present. In this review we will highlight the possible advantages and drawbacks of using this approach as a therapeutic strategy while focusing on the experimental models necessary for a better understanding of the phenomenon. Specifically, we will discuss in brief the cellular signaling pathways associated with the onset of a hypertrophic phenotype in chondrocytes during the progression of OA and will analyze in depth the advantages and disadvantages of various models that have been used to mimic it. Afterwards, we will present the strategies developed and proposed to impede chondrocyte hypertrophy and cartilage matrix mineralization/calcification. Finally, we will examine the future perspectives of OA therapeutic strategies

Hard Knapsack Problems That Are Easy for Local Search

Chv&apos;atal (1980) describes a class of zero-one knapsack problems provably difficult for branch and bound and dynamic programming algorithms. Chung et al. (1988) identifies a class of integer knapsack problems hard for branch and bound algorithms. We show that for both classes of problems local search provides optimal solutions quickly. Keywords : knapsack problem * local search * computational complexity Correspondence should be directed to the second author 1 Introduction Chv&apos;atal (1980) describes a class of instances of zero-one knapsack problems due to Todd. ( We shall henceforth refer to these problems as the TODD class of problems. ) He shows that a wide class of algorithms --- including all based on branch and bound or dynamic programming --- find it difficult to solve problems in the TODD class. More precisely, the time required by these algorithms to solve instances of problems belonging to the TODD class grows as an exponential function of the problem parameters. Chung et a..

Impact of Climate Change on Livestock Production: A Review

ABSTRACT Climate change is seen as a major threat to the survival of many species, ecosystems and the sustainability of livestock production systems in many parts of the world. Green house gases (GHG) are released in the atmosphere both by natural sources and anthropogenic (human related) activities. An attempt has been made in this article to understand the contribution of ruminant livestock to climate change and to identify the mitigation strategies to reduce enteric methane emission in livestock. In Indian subcontinent, heat stress is the most important climatic stress. Heat stress adversely affecting productive and reproductive performance of livestock, and hence reducing the total area where high yielding dairy cattle may be economically reared. The livestock sector which will be a sufferer of climate change is itself a large source of methane emissions contributing about 18% of total enteric methane budget. Ruminant livestock such as cattle, buffalo, sheep and goats contributes the major proportion of total agricultural emission of methane .In India, although the emission rate per animal is much lower than the developed countries, due to vast livestock population the total annual methane emissions from Indian livestock ranged from 7.26 to 10.4 MT/year. In India more than 90% of the total methane emission from enteric fermentation is being contributed by the large ruminants (cattle and buffalo) and rest from small ruminants and others. Generally CH 4 reduction strategies can be grouped under two broad categories such as management and nutritional strategies. Although the reduction in GHG emissions from livestock industries are seen as high priorities, strategies for reducing emissions should not reduce the economic viability of enterprises if they are to find industry acceptability. Keywords: Climate change, methane, mitigation, ruminants, livestock production The crop livestock system is one of the most important characteristics of Indian agrarian economy and livestock sector is the integral part of India&apos;s agriculture sector. Indian livestock sector provides sustainability and stability to the national economy by contributing to farm energy and food security. Livestock sector no

Growth and characteristics of lead-substituted rare earth manganites

The growth of $R_{1-x}$ $Pb_xMnO_3$ (R=La, Nd, [La,Nd]) single crystals by $PbO/PbF_2$ flux is described with optimized growth conditions. The structure of $Nd_{1-x}$ $Pb_xMnO_3$ changes from orthorhombic (x=0, Pnma) to tetragonal (x=0.25, P4/mmm) to cubic (x=0.38, Pm3¯m) as x increases. These changes are attributed to the progressive removal of inter-octahedral tilting and minimization of octahedral distortion leading to a higher symmetry as doping concentration increases. The $T_C$ of this system increases from 110 to 192 K for Pb concentration varying from x=0.15 to 0.42. The $T_{MI}$ also follows a similar trend. It is observed that $\langle r_A\rangle$ and $\sigma^2$ are the controlling parameters which influence the transport and magnetic properties of $La_{0.7-y}Nd_yPb_{0.3}MnO_3$. The presence of spin wave excitations are observed prominently in $La_{0.7}Pb_{0.3}MnO_3$ at low-temperature which is not so in case of Nd-based compounds. The total magnetic moments of all the Nd-based systems at low-temperature are influenced by Nd. The low-temperature specific heat data of $La_{0.7-y}Nd_yPb_{0.3}$ $MnO_3$ is analyzed and contributions of different mechanisms are discussed. It is noticed that the Schottky anomaly is present in specific heat at low-temperature only in Nd-based compounds