1,663 research outputs found
Discrete systems related to some equations of the Painlev\'e-Gambier classification
We derive integrable discrete systems which are contiguity relations of two
equations in the Painlev\'e-Gambier classification depending on some parameter.
These studies extend earlier work where the contiguity relations for the six
transcendental Painlev\'e equations were obtained. In the case of the Gambier
equation we give the contiguity relations for both the continuous and the
discrete system.Comment: 10 page
Natural Suppression of the Aquatic Weed Salvinia molesta D.S. Mitchell, by Two Previously Unreported Fungal Pathogens
Salvinia molesta
D. S. Mitchell (Salviniaceae), variously
called giant salvinia, water fern or African payal, is a vegetatively
reproducing, perennial, free-floating, aquatic weed,
native to southeastern Brazil (Waterhouse and Norris 1987).
It (hereafter called salvinia) is a very serious weed in most
regions outside its native range (Harley and Mitchell 1981)
including India. The purpose of this paper is to report
on two fungal pathogens that were found to be the cause
of a sudden decline in salvinia in Bangalore.(PDF has 4 pages.
Notched and Unnotched Fatigue Behavior of Angle-Ply Graphite/Epoxy Composites
The axial fatigue behavior of both notched and unnotched graphite/epoxy composites was studied. In unnotched studies, conducted on a 0/+ or - 30 3S AS/3501 laminate, S-N curves were determined for various stress ratios R using simply supported test specimens. Apparent fatigue limits in tension-tension (T-T) and compression-compression (C-C) cycling occurred at about 60% of the respective static strengths. The overall results were expressed in the form of a constant life diagram showing the relationship between mean stress and stress amplitude. The diagram illustrates a skew-symmetry in fatigue life caused by the relatively low compressive strength of the unrestrained test specimens used. In effect, a maximum in fatigue properties occurs at a positive value of mean stress. Results are of significance in situations where structural members are buckling or crippling critical in design
Integrable systems without the Painlev\'e property
We examine whether the Painlev\'e property is a necessary condition for the
integrability of nonlinear ordinary differential equations. We show that for a
large class of linearisable systems this is not the case. In the discrete
domain, we investigate whether the singularity confinement property is
satisfied for the discrete analogues of the non-Painlev\'e continuous
linearisable systems. We find that while these discrete systems are themselves
linearisable, they possess nonconfined singularities
Constructing Integrable Third Order Systems:The Gambier Approach
We present a systematic construction of integrable third order systems based
on the coupling of an integrable second order equation and a Riccati equation.
This approach is the extension of the Gambier method that led to the equation
that bears his name. Our study is carried through for both continuous and
discrete systems. In both cases the investigation is based on the study of the
singularities of the system (the Painlev\'e method for ODE's and the
singularity confinement method for mappings).Comment: 14 pages, TEX FIL
Singularity confinement and algebraic integrability
Two important notions of integrability for discrete mappings are algebraic
integrability and singularity confinement, have been used for discrete
mappings. Algebraic integrability is related to the existence of sufficiently
many conserved quantities whereas singularity confinement is associated with
the local analysis of singularities. In this paper, the relationship between
these two notions is explored for birational autonomous mappings. Two types of
results are obtained: first, algebraically integrable mappings are shown to
have the singularity confinement property. Second, a proof of the non-existence
of algebraic conserved quantities of discrete systems based on the lack of
confinement property is given.Comment: 18 pages, no figur
Effect of ethanolic extract of Centella asiatica on maximal electroshock seizure in albino mice
Background: Animal models had always served as integral part in introducing newer drugs for epilepsy. India has long tradition of using herbal medicines. Centella asiatica is an ingredient of various ayurvedic preparations to treat brain related disorders like insanity, memory loss and epilepsy. This research is done to find out the usefulness of Centella asiatica in epilepsy.  Methods: Ethanolic extract of the plant is prepared using Soxhlet apparatus. Experimental seizure is induced in albino mice by maximal electroshock method. Resulting seizure goes through different phases. Duration of the phase of hind limb extension was the measured data. Clinically used anti epileptic drugs can abolish hind limb extension. Effect is compared to that of standard drug phenytoin. Four different doses of the plant extract; 100mg, 200mg, 500mg and 1000mg per kilogram bodyweight was given orally. Statistical analysis of data was done by one way ANOVA and Dunnett test.Results: Ethanolic extract of Centella asiatica exhibited statistically significant protection from maximal electroshock seizures. All given doses of the extract had p<0.05 when compared to control.Conclusions: Centella asiatica is potential source of anti-epileptic drug. Detailed phytochemical studies and animal experiments are recommended
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