100 research outputs found
Lyapunov stability analysis of a competition model with crowding effects
No full textThe present study is connected to the analysis of a nonlinear system that covered a wide range of mathematical
biology in terms of competition, cooperation, and symbiosis interactions between two species. We focus on how
populations change their densities when two different species follow the non-symmetric logistic growth laws.
We have investigated the stability of the corresponding densities of population, and to control the convergence
of solutions by proper choice of interacting constant and periodic parameters. It shows the effect of crowding
tolerance on both species. It will show that there exists an infinite number of coexistence solutions if the
resource distributions are identical for both populations. If the carrying capacity of the first species exceeds the
rest one, then eventually the second population drops down to extinction. The results are presented studying
the Lyapunov functional, phase portraits, and in a series of numerical examples
En plaque meningioma with angioinvasion
No full textEn plaque meningioma is a rare type of meningioma characterized by infiltrative nature, sheet-like growth and at times invading the bone. We report here a case of en plaque meningioma with typical grade I histomorphology along with unusual feature of angioinvasion. The patient was a 55-year-old man presenting with headache and painful proptosis of right eye. Imaging modalities revealed an en -plaque meningioma extending into the right sylvian fissure, with thickening of right temporal calvarium, greater wing of sphenoid and extension into the orbit. Magnetic resonance angiography showed medial displacement of right middle cerebral artery. The tumor was removed from the sylvian fissure and right temporal convexity. However, only subtotal removal of the intraorbital part was possible. Histology showed a meningothelial meningioma with low tumor cell proliferation, but infiltration into the bone, skeletal muscle and angioinvasion. Recognition of meningiomas en plaque is useful, as these tumors are difficult to resect completely, and are more prone to undergo recurrence or malignant change. In addition, angioinvasion seen in this tumor may have additional prognostic significance
Multireference coupled cluster calculations on CH<SUP>2+</SUP>
No full textIn this paper we examine the potential energy surface of CH2+ to reinvestigate the controversy surrounding the stability of this dication using the Fock space version of multireference coupled cluster theory
Influence of bond length variation on correlated static exchange potential: a case study in e<SUP>-</SUP>-N<SUB>2</SUB> scattering
No full textWe discuss in this note how the correlated static exchange potential changes with bond length for N2 molecule where the earlier extensive results at equilibrium exist. We have used many-body coupled cluster technique for this study. Its relevance to e--N2 scattering is also discussed
Exciplex Formation of Naphthalene & Biphenyl with N,N,N',N'-Tetramethyl-p-phenyldiamine in Solution
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Stationary response with exponential transformation: A perturbative analysis for molecular static properties
No full textWARM ELECTRON COEFFICIENT OF TWO DIMENSIONAL ELECTRON GAS IN A GaAs-AlGaAs HETEROJUNCTIONS AT LOW TEMPERATURES
No full textAlloy scattering limited mobility of two-dimensional electron gas in quaternary alloy semiconductors
No full textThe influence of density in population dynamics with strong and weak Allee effect
No full textIn this paper, we consider a reaction–diffusion model in population dynamics and study the impact of different types of Allee effects with logistic growth in the heterogeneous closed region. For strong Allee effects, usually, species unconditionally die out and an extinction-survival situation occurs when the effect is weak according to the resource and sparse functions. In particular, we study the impact of the multiplicative Allee effect in classical diffusion when the sparsity is either positive or negative. Negative sparsity implies a weak Allee effect, and the population survives in some domain and diverges otherwise. Positive sparsity gives a strong Allee effect, and the population extinct without any condition. The influence of Allee effects on the existence and persistence of positive steady states as well as global bifurcation diagrams is presented. The method of sub-super solutions is used for analyzing equations. The stability conditions and the region of positive solutions (multiple solutions may exist) are presented. When the diffusion is absent, we consider the model with and without harvesting, which are initial value problems (IVPs) and study the local stability analysis and present bifurcation analysis. We present a number of numerical examples to verify analytical results
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