Enhanced grain surface effect on magnetic properties of nanometric La0.7Ca0.3MnO3 manganite : Evidence of surface spin freezing of manganite nanoparticles

We have investigated the effect of nanometric grain size on magnetic properties of single phase, nanocrystalline, granular La0.7Ca0.3MnO3 (LCMO) sample. We have considered core-shell structure of our LCMO nanoparticles, which can explain its magnetic properties. From the temperature dependence of field cooled (FC) and zero-field cooled (ZFC) dc magnetization (DCM), the magnetic properties could be distinguished into two regimes: a relatively high temperature regime T > 40 K where the broad maximum of ZFC curve (at T = Tmax) is associated with the blocking of core particle moments, whereas the sharp maximum (at T = TS) is related to the freezing of surface (shell) spins. The unusual shape of M (H) loop at T = 1.5 K, temperature dependent feature of coercive field and remanent magnetization give a strong support of surface spin freezing that are occurring at lower temperature regime (T < 40 K) in this LCMO nanoparticles. Additionally, waiting time (tw) dependence of ZFC relaxation measurements at T = 50 K show weak dependence of relaxation rate [S(t)] on tw and dM/dln(t) following a logarithmic variation on time. Both of these features strongly support the high temperature regime to be associated with the blocking of core moments. At T = 20 K, ZFC relaxation measurements indicates the existence of two different types of relaxation processes in the sample with S(t) attaining a maximum at the elapsed time very close to the wait time tw = 1000 sec, which is an unequivocal sign of glassy behavior. This age-dependent effect convincingly establish the surface spin freezing of our LCMO nanoparticles associated with a background of superparamagnetic (SPM) phase of core moments.Comment: 41 pages, 10 figure

Chaos in Sandpile Models

We have investigated the "weak chaos" exponent to see if it can be considered as a classification parameter of different sandpile models. Simulation results show that "weak chaos" exponent may be one of the characteristic exponents of the attractor of \textit{deterministic} models. We have shown that the (abelian) BTW sandpile model and the (non abelian) Zhang model posses different "weak chaos" exponents, so they may belong to different universality classes. We have also shown that \textit{stochasticity} destroys "weak chaos" exponents' effectiveness so it slows down the divergence of nearby configurations. Finally we show that getting off the critical point destroys this behavior of deterministic models.Comment: 5 pages, 6 figure

Renormalization group approach to an Abelian sandpile model on planar lattices

One important step in the renormalization group (RG) approach to a lattice sandpile model is the exact enumeration of all possible toppling processes of sandpile dynamics inside a cell for RG transformations. Here we propose a computer algorithm to carry out such exact enumeration for cells of planar lattices in RG approach to Bak-Tang-Wiesenfeld sandpile model [Phys. Rev. Lett. {\bf 59}, 381 (1987)] and consider both the reduced-high RG equations proposed by Pietronero, Vespignani, and Zapperi (PVZ) [Phys. Rev. Lett. {\bf 72}, 1690 (1994)] and the real-height RG equations proposed by Ivashkevich [Phys. Rev. Lett. {\bf 76}, 3368 (1996)]. Using this algorithm we are able to carry out RG transformations more quickly with large cell size, e.g. $3 \times 3$ cell for the square (sq) lattice in PVZ RG equations, which is the largest cell size at the present, and find some mistakes in a previous paper [Phys. Rev. E {\bf 51}, 1711 (1995)]. For sq and plane triangular (pt) lattices, we obtain the only attractive fixed point for each lattice and calculate the avalanche exponent $\tau$ and the dynamical exponent $z$. Our results suggest that the increase of the cell size in the PVZ RG transformation does not lead to more accurate results. The implication of such result is discussed.Comment: 29 pages, 6 figure

Nonuniversal exponents in sandpiles with stochastic particle number transfer

We study fixed density sandpiles in which the number of particles transferred to a neighbor on relaxing an active site is determined stochastically by a parameter $p$. Using an argument, the critical density at which an active-absorbing transition occurs is found exactly. We study the critical behavior numerically and find that the exponents associated with both static and time-dependent quantities vary continuously with $p$.Comment: Some parts rewritten, results unchanged. To appear in Europhys. Let

Order Parameter and Scaling Fields in Self-Organized Criticality

We present a unified dynamical mean-field theory for stochastic self-organized critical models. We use a single site approximation and we include the details of different models by using effective parameters and constraints. We identify the order parameter and the relevant scaling fields in order to describe the critical behavior in terms of usual concepts of non equilibrium lattice models with steady-states. We point out the inconsistencies of previous mean-field approaches, which lead to different predictions. Numerical simulations confirm the validity of our results beyond mean-field theory.Comment: 4 RevTex pages and 2 postscript figure

STUDY ON AVAILABILITY AND AFFORDABILITY OF ANTI HYPERTENSIVE MEDICINES IN THE STATE OF KERALA

Objective: Since the 1970s, one of the smallest Indian States, Kerala, has been internationally applauded for its excellent performance in its health indicators. Even if mortality is low, the morbidity (those suffering from chronic/non-communicable diseases) levels in urban and rural is high in Kerala compared to other Indian states. Gradually, the public sector becomes incapable to convene the demands for health care and people have responded to this meagerness by increasing the use of an emerging private sector. To overcome this scenario, Kerala government established KMSCL for promoting access to medicines to the patients approaching the public hospitals in Kerala by making available selected essential medicines at free of cost. The present study was conducted to evaluate the availability, cost and affordability of anti-hypertensive medicines in Kerala. Methods: This prospective, observational study was conducted in Trivandrum district in Kerala, from June 2013 to November 2013. Three types of medication prices were taken into contemplation with the intension for calculation purposes, the highest and the lowest branded medication costs in private pharmacy and Karunya Community Pharmacy (KCP) prices. Affordability was calculated for the different level of skilled workers and through the wages fixed by the government of Kerala for these categories, who were consuming the medications at the time. A comparison was also done between various treatment guidelines of hypertension. Results: There was 15.5% to 230% price variation between the highest and lowest price of branded anti-hypertensive medicines respectively. For treating Stage 3 of hypertension; unskilled and highly skilled workers had to spend a minimum of 1.22 and 0.84 wage days respectively and a maximum of 5.23 and 4.34 wage days respectively in private pharmacies. All the medicines required for the treatments of hypertension were available in both private and KCP. Conclusion: The study revealed that there was an average availability at of antihypertensive medicines in public health facilities. The availability of all medicines at KCP in low price shows the good impact of KMSCL for promoting access of medicines to the poor

Codeposition of nanocrystalline aluminides on a copper substrate

The present study concerns codeposition of nanocrystalline aluminide particles (NbAl3 and Cu9Al4) along with electrodeposition of Cu on a Cu substrate. It is shown that the success of codeposition primarily depends on the selection of an appropriate electrolyte. Following codeposition under an optimum deposition condition, the microstructure, phase identity and composition of the deposit layer have been studied. In addition, microhardness and electrical resistivity of the deposit have been determined. A suitable correlation of the microstructure and composition of the deposit with its properties suggests that codeposition of NbAl3 is more effective in enhancing the hardness. However, codeposition beyond a limit adversely affects the electrical conductivity. The optimum conditions for codeposition to enhance hardness without adversely affecting conductivity have been determined. Finally, it is predicted codeposition could be a suitable technique for developing a surface composite microstructure with uniform distribution of nanocrystalline aluminide particles

A study on prescribing pattern and medication adherence in elderly COPD and bronchial asthma patients in a tertiary care teaching hospital

Background: Chronic obstructive pulmonary disease and bronchial asthma are common among elderly people and have become a major public health concern of today. The purpose of this study is to identify the prescription pattern and role of medication adherence in the COPD and bronchial asthma. Prescription pattern monitoring (PPMS) are mainly focus on prescribing, dispensing, administering of drugs they promote appropriate use of monitored drugs and reduction of abuse/misuse.Methods: A hospital based prospective observational study was conducted at department of medicine in Rajah Muthiah Medical College and Hospital. A total of 90 patients were enrolled based on inclusion and exclusion criteria and the data was collected using designed data collection form.Results: Out of 90 patients, male (81.10%) and female (18.90%) are reported with COPD and bronchial asthma. On prevalence 57 (63.34%) of patients with co-morbidities and without co-morbidities 33 (36.66%). Among co-morbidity patients, 38.90% of patients has type-2 diabetes mellitus. PPA indicate that cephalosporins (46.68%), macrolides (38.88%) class of antibiotic are used prominently along with corticosteroids of hydrocortisone 47 (62.66%) and prednisolone 28 (37.34%). 47 (62.66%) patients received expectorants and anti-tussive in that, Ipratropium bromide + levosalbutamol (50%) are commonly prescribed.Conclusions: This study concludes that COPD and bronchial asthma was most predominant in elderly patients and its treated with mainly antibiotics and corticosteroids with bronchodilators in the way of inhalers and nebulizers. The rational use of drugs and patient counselling reflects a better medication adherence

Clustering properties of a generalised critical Euclidean network

Many real-world networks exhibit scale-free feature, have a small diameter and a high clustering tendency. We have studied the properties of a growing network, which has all these features, in which an incoming node is connected to its $i$th predecessor of degree $k_i$ with a link of length $\ell$ using a probability proportional to $k^\beta_i \ell^{\alpha}$. For $\alpha > -0.5$, the network is scale free at $\beta = 1$ with the degree distribution $P(k) \propto k^{-\gamma}$ and $\gamma = 3.0$ as in the Barab\'asi-Albert model ($\alpha =0, \beta =1$). We find a phase boundary in the $\alpha-\beta$ plane along which the network is scale-free. Interestingly, we find scale-free behaviour even for $\beta > 1$ for $\alpha < -0.5$ where the existence of a new universality class is indicated from the behaviour of the degree distribution and the clustering coefficients. The network has a small diameter in the entire scale-free region. The clustering coefficients emulate the behaviour of most real networks for increasing negative values of $\alpha$ on the phase boundary.Comment: 4 pages REVTEX, 4 figure