Size-dependent magnetization fluctuations in NiO nanoparticles

The finite size and surface roughness effects on the magnetization of NiO nanoparticles is investigated. A large magnetic moment arises for an antiferromagnetic nanoparticle due to these effects. The magnetic moment without the surface roughness has a non-monotonic and oscillatory dependence on $R$, the size of the particles, with the amplitude of the fluctuations varying linearly with $R$. The geometry of the particle also matters a lot in the calculation of the net magnetic moment. An oblate spheroid shape particle shows an increase in net magnetic moment by increasing oblateness of the particle. However, the magnetic moment values thus calculated are very small compared to the experimental values for various sizes, indicating that the bulk antiferromagnetic structure may not hold near the surface. We incorporate the surface roughness in two different ways; an ordered surface with surface spins inside a surface roughness shell aligned due to an internal field, and a disordered surface with randomly oriented spins inside surface roughness shell. Taking a variational approach we find that the core interaction strength is modified for nontrivial values of $\Delta$ which is a signature of multi-sublattice ordering for nanoparticles. The surface roughness scale $\Delta$ is also showing size dependent fluctuations, with an envelope decay $\Delta\sim R^{-1/5}$. The net magnetic moment values calculated using spheroidal shape and ordered surface are close to the experimental values for different sizes.Comment: 19 pages, 8 figures, Accepted for publication in Int. J. Mod. Phys.

Nehari manifold approach for fractional Kirchhoff problems with extremal value of the parameter

In this work we study the following nonlocal problem \begin{equation*} \left\{ \begin{aligned} M(\|u\|^2_X)(-\Delta)^s u&= \lambda {f(x)}|u|^{\gamma-2}u+{g(x)}|u|^{p-2}u &&\mbox{in}\ \ \Omega, u&=0 &&\mbox{on}\ \ \mathbb R^N\setminus \Omega, \end{aligned} \right. \end{equation*} where $\Omega\subset \mathbb R^N$ is open and bounded with smooth boundary, $N>2s, s\in (0, 1), M(t)=a+bt^{\theta-1},\;t\geq0$ with $\theta>1, a\geq 0$ and $b>0$. The exponents satisfy $1<\gamma<2<{2\theta<p<2^*_{s}=2N/(N-2s)}$ (when $a\neq 0$) and $2<\gamma<2\theta<p<2^*_{s}$ (when $a=0$). The parameter $\lambda$ involved in the problem is real and positive. The problem under consideration has nonlocal behaviour due to the presence of nonlocal fractional Laplacian operator as well as the nonlocal Kirchhoff term $M(\|u\|^2_X)$, where $\|u\|^{2}_{X}=\iint_{\mathbb R^{2N}} \frac{|u(x)-u(y)|^2}{\left|x-y\right|^{N+2s}}dxdy$. The weight functions $f, g:\Omega\to \mathbb R$ are continuous, $f$ is positive while $g$ is allowed to change sign. In this paper an extremal value of the parameter, a threshold to apply Nehari manifold method, is characterized variationally for both degenerate and non-degenerate Kirchhoff cases to show an existence of at least two positive solutions even when $\lambda$ crosses the extremal parameter value by executing fine analysis based on fibering maps and Nehari manifold

EFFECT OF MADHU TAILIKA BASTI AND SHAMANA AUSHADHI IN POLY-CYCSTIC OVARIAN DISEASES

Polycystic ovarian disease (PCOD) is emerging as a main cause of menstrual irregularities, mainly observed in age group of 12-45 yrs of age. Based on present data available, 5-15% of females suffer from this condition that includes symptoms like obesity, irregular menstrual cycle, hirsutism etc. In Ayurveda though exact correlation cannot be ascertained, it can be better explained under Rasa nimittaja vyadhi, where the involvement of Medo dhatu, Vata and Kapha doshas are seen. Madhutailika basti which carries numerous positive clinical results as per the classical reference based on the various pharmacological properties on Medo dhatu dustigata vyadhis, because of its ingredients. Based on the available references, Madhutailika basti along with other Shaman ausudhis are taken for a pilot observational study at Shri Kalabyraveshwaraswamy Ayurvedic Medical College Hospital &amp; Research Centre Vijayanagar Bangalore. Post approval of the institution ethical committee, Madhutailika basti was administered to selected patients for a period of 8 days followed by administration of Shaman aushadis for a period of next 3 months. The overall results showed marked improvement in 70%, moderate improvement in 20% of the patients. All patients completed the study successfully without any drop outs

Fluctuation Induced Non-Fermi Liquid Behavior near a Quantum Phase Transition in Itinerant Electron Systems

The signature for a non-Fermi liquid behavior near a quantum phase transition has been observed in thermal and transport properties of many metallic systems at low temperatures. In the present work we consider specific examples of itinerant ferromagnet as well as antiferromagnet in the limit of vanishing transition temperature. The temperature variation of spin susceptibility, electrical resistivity, specific heat, and NMR relaxation rates at low temperatures is calculated in the limit of infinite exchange enhancement within the frame work of a self consistent spin fluctuation theory. The resulting non-Fermi liquid behavior is due to the presence of the low lying critically damped spin fluctuations in these systems. The theory presented here gives the leading low temperature behavior, as it turns out that the fluctuation correlation term is always smaller than the mean fluctuation field term in three as well as in two space dimensions. A comparison with illustrative experimental results of these properties in some typical systems has been done. Finally we make some remarks on the effect of disorder in these systems.Comment: File RevTex, 7 Figures available on request, Abstract and text modified, To appear in Phys. Rev.

A preliminary study of multilevel geographic distribution &amp; prevalence of Aedes aegypti (Diptera: Culicidae) in the state of Goa, India

Background &amp; objectives: Dengue virus activity has never been reported in the state of Goa. The present study was carried out to document a multilevel geographic distribution, prevalence and preliminary analysis of risk factors for the invasions of Aedes aegypti in Goa. Methods: A geographic information system (GIS) based Ae. aegypti surveys were conducted in dry (April 2002) and wet (July 2002) seasons in the rural and urban settlements. The random walk method was used for household coverage. The non-residential area visits included ancillaries of roadways, railways, air-and seaports. Simultaneous adult mosquito collections and one-larva per container technique were adopted. Results: The Ae. aegypti larval and adult prevalence was noted in all the four urban areas in both dry (Density index (DI)= 3 to 6) and wet (DI= 5 to 7) seasons and only one out of 3 villages showed Ae aegypti presence in wet season (DI= 5 to 7). In the residential areas, hutments showed higher relative prevalence indices (Breteau index, BI=100; container index, CI=11.95; adult house index, AHI=13.33) followed by close set cement houses (BI=44.1; CI=12.0; AHI=11.24). Ae aegypti relative prevalence indices were also more for households with pets (BI=85.11; CI=12.5; AHI= 42.85); those with tap had higher risk (larval house index, LHI =32.03; relative risk, RR&gt;2, n=256). Plastic drum was the most preferred breeding place (χ2 = 19.81; P&lt;0.01; RR=3.41) among domestic containers and rubber tyres (χ2 = 11.86; P&lt;0.01; RR=3.61)among sundry/rainfilled containers. Interpretation &amp; conclusion: Established Ae aegypti prevalence in the urban settlements during dry and wet seasons and its scattered distribution in a rural settlement spell risk of dengue infection at macro-level. In the residential areas nature and types of the households, tap water supply and storage and communities' attitude and practices contribute to sustained meso-level risk of Ae aegypti prevalence dependant DEN. The non-residential areas offer transient meso-level risk as Ae aegypti prevalence was seasonally unstable and monsoon dependent. Risk at micro-level was due to the preferred larval habitats of Ae aegypti breeding viz., residential plastic-ware and tyres, and transport tyres in non-residential areas

Dynamics in a noncommutative phase space

Dynamics has been generalized to a noncommutative phase space. The noncommuting phase space is taken to be invariant under the quantum group $GL_{q,p}(2)$. The $q$-deformed differential calculus on the phase space is formulated and using this, both the Hamiltonian and Lagrangian forms of dynamics have been constructed. In contrast to earlier forms of $q$-dynamics, our formalism has the advantage of preserving the conventional symmetries such as rotational or Lorentz invariance.Comment: LaTeX-twice, 16 page