Random replicators with high-order interactions

We use tools of the equilibrium statistical mechanics of disordered systems to study analytically the statistical properties of an ecosystem composed of N species interacting via random mutual interactions, as well as via deterministic self-interactions of order p>/=2. We show that the main effect of increasing the order of the interactions among the species is to make the system less competitive, in the sense that the fraction of extinct species is greatly reduced. In addition, we find that for p>2 there is a threshold value which gives a lower bound to the concentration of the surviving species, preventing then the existence of rare species and, consequently, increasing the robustness of the ecosystem to external perturbations.     

Chemoselective Protection of Hydroxyl Groups and Deprotection of Silyl Ethers

Summary.  Trimethylsilylation of alcohols and phenols is carried out using hexamethyldisilazane and LiClO₄ under microwave irradiation and neutral conditions. The deprotection of silyl ethers is carried out similarly using natural kaolinitic clay and a few drops of water. Received March 1, 2001. Accepted (revised) April 17, 2001     

Effect of ethanolic extract of Rubia peregrina L. (Rubiaceae) on monoamine-mediated behaviour

In the traditional system of medicine in Sardinia, Rubia peregrina (RP) is reported as an aphrodisiac herb. Since aphrodisiacs may also have dopaminergic activity, and there can be a reciprocal relationship between dopaminergic and serotonergic functions in the central nervous system, the aim here was to study the effect of the ethanolic extract of the aerial parts of R. peregrina on monoamine-mediated behaviour. The RP (100 and 200?mg?kg(-1) intraperitoneally) significantly inhibited haloperidol (1?mg?kg(-1) i.p.) induced catalepsy in mice (p?相似文献   

Comparison theorems for nonlinear elliptic systems of second order with applications

In this paper comparison theorems concerning Dirichlet problem for a class of weakly coupled nonlinear second order elliptic systems have been developed. Some applications of these results to deflection or vibration of membranes and plates are also given.     

Protective effect of Rubia cordifolia on reserpine-induced orofacial dyskinesia

In this study, the neuroprotective potential and in vivo antioxidant status of extract of roots and rhizomes of Rubia cordifolia L (MERC) in reserpine-induced orofacial dyskinesia was studied. Reserpine (1 mg/kg, s.c.) on day 1, 3 and 5 was used to induce orofacial dyskinesia. At the end of treatment schedule, MERC significantly inhibited reserpine-induced vacuous chewing movements, tongue protrusions, orofacial bursts, catalepsy. MERC significantly increased locomotion and rearing in open field test. MERC exhibited significant elevation in the levels of superoxide dismutase, catalase, glutathione reductase and inhibition of lipid peroxidation in forebrain region, compared with the reserpine treated group. It significantly elevated dopamine levels in the forebrain region. GCMS revealed the presence of anthraquinones, having strong antioxidant activity. It is concluded that oxidative stress might play an important role in reserpine-induced abnormal oral movements and MERC significantly protected animals against reserpine-induced orofacial dyskinesia and has great potential in treatment of neuroleptic induced orofacial dyskinesia.     

Ethanolic extract of Rubia peregrina L. (Rubiaceae) inhibits haloperidol-induced catalepsy and reserpine-induced orofacial dyskinesia

In the traditional Sardinian system of medicine, Rubia peregrina L. (Rubiaceae) is reported as an aphrodisiac herb. Since the aphrodisiacs may also have antioxidant and dopaminergic activities, the aim of this study was to study the effect of ethanolic extract of aerial parts of R. peregrina for the scavenging of free DPPH radicals and the inhibition of haloperidol-induced catalepsy in mice and reserpine-induced orofacial dyskinesia in rats. The extract exhibited significant antioxidant activity in a free radical DPPH assay with IC(50)?=?55.6?μg?mL(-1), which was very close to IC(50) of ascorbic acid. The extract of R. peregrina (100 and 200?mg?kg(-1) intraperitoneally, i.p.) significantly inhibited haloperidol (1?mg?kg(-1) i.p.) - induced catalepsy in mice (p?相似文献   

Stability-Indicating HPTLC Method for the Determination of Atorvastatin and Ezetimibe: Application to Pharmaceutical Dosage Forms

JPC – Journal of Planar Chromatography – Modern TLC -     

Envirocat Epzg® as an Efficient Heterogenous Catalyst for Thioacetalization of Carbonyl Compounds

The reaction of carbonyl compounds with 1,2-ethanedithiol was efficiently catalyzed by Envirocat EPZG® to afford the corresponding dithioacetals in excellent yields.     

Flow through a helically coiled annulus

In this paper the flow is studied of an incompressible viscous fluid through a helically coiled annulus, the torsion of its centre line taken into account. It has been shown that the torsion affects the secondary flow and contributes to the azimuthal component of velocity around the centre line. The symmetry of the secondary flow streamlines in the absence of torsion, is destroyed in its presence. Some stream lines penetrate from the upper half to the lower half, and if is further increased, a complete circulation around the centre line is obtained at low values of for all Reynolds numbers for which the analysis of this paper is valid, being the ratio of the torsion of the centre line to its curvature.Nomenclature A =constant - a outer radius of the annulus - b unit binormal vector to C - C helical centre line of the pipe - D rL - g 1000 - K Dean number=Re² - L 1+r sin - M (L ²+ ² r ²)^1/2 - n unit normal vector to C - P, P pressure and nondimensional pressure - p ₀, p pressures of O(1) and O() - Re Reynolds number=aW ₀/ - (r, , s), (r, , s) coordinates and nondimensional coordinates - nonorthogonal unit vectors along the coordinate directions - r ₀ radius of the projection of C - t unit tangent vector to C - V _r, V , V _s velocity components along the nonorthogonal directions - V_r, V, V _s nondimensional velocity components along - W ₀ average velocity in a straight annulus Greek symbols , curvature and nondimensional curvature of C - U, V, W lowest order terms for small in the velocity components along the orthogonal directions t - _r, , _s first approximations to V _r , V, V _s for small - =/=/ - kinematic viscosity - density of the fluid - , torsion and nondimensional torsion of C - , stream function and nondimensional stream function - nondimensional streamfunction for U, V - a inner radius of the annulus After this paper was accepted for publication, a paper entitled On the low-Reynolds number flow in a helical pipe, by C.Y. Wang, has appeared in J. Fluid. Mech., Vol 108, 1981, pp. 185–194. The results in Wangs paper are particular cases of this paper for =0, and are also contained in [9].