2,485 research outputs found
On the particle paths and the stagnation points in small-amplitude deep-water waves
In order to obtain quite precise information about the shape of the particle
paths below small-amplitude gravity waves travelling on irrotational deep
water, analytic solutions of the nonlinear differential equation system
describing the particle motion are provided. All these solutions are not closed
curves. Some particle trajectories are peakon-like, others can be expressed
with the aid of the Jacobi elliptic functions or with the aid of the
hyperelliptic functions. Remarks on the stagnation points of the
small-amplitude irrotational deep-water waves are also made.Comment: to appear in J. Math. Fluid Mech. arXiv admin note: text overlap with
arXiv:1106.382
The "Hot Spots" Conjecture on the Vicsek Set
We prove the Hot Spot conjecture on the Vicsek set. Specifically, we show
that every eigenfunction of the second smallest eigenvalue of the Neumann
Laplacian on the Vicsek set attains its maximum and minimum on the boundary.Comment: We made changes suggested by the anonymous referee and editors. The
paper is accepted for publication in the Special Issue on Harmonic Analysis:
Smooth and Non-Smooth, Demonstratio Mathematic
A para-differential renormalization technique for nonlinear dispersive equations
For \alpha \in (1,2) we prove that the initial-value problem \partial_t
u+D^\alpha\partial_x u+\partial_x(u^2/2)=0 on \mathbb{R}_x\times\mathbb{R}_t;
u(0)=\phi, is globally well-posed in the space of real-valued L^2-functions. We
use a frequency dependent renormalization method to control the strong low-high
frequency interactions.Comment: 42 pages, no figure
On special quadratic birational transformations of a projective space into a hypersurface
We study transformations as in the title with emphasis on those having smooth
connected base locus, called "special". In particular, we classify all special
quadratic birational maps into a quadric hypersurface whose inverse is given by
quadratic forms by showing that there are only four examples having general
hyperplane sections of Severi varieties as base loci.Comment: Accepted for publication in Rendiconti del Circolo Matematico di
Palerm
Environmental impact assessement related to metallurgical industry activities
In this work is presented the impact assess of metallurgical specific activities on the environment through global pollution index calculation. The pollution index value calculated for environmental components: air, water, soil, vegetation, noise, waste, population health status indicated an environment subject to human effect within acceptable limits
Metabolic alterations in experimental models of depression
Introduction: Major depressive disorder is one of the most prevalent psychiatric disorders and is associated with a severe impact on the personal functioning, thus with incurring significant direct and indirect costs. The presence of depression in patients with medical comorbidities increases the risks of myocardial infarction and decreases diabetes control, and adherence to treatment. The mechanism through which these effects are produced is still uncertain. Objectives of this study were to evaluate the metabolic alterations in female Wistar rats with induced depression, with and without administration of Agomelatine. The methods included two experiments. All data were analyzed by comparison with group I (control), and with each other. In the first experiment we induced depression by: exposure to chronic mild stress-group II; olfactory bulbectomy-group III; and exposure to chronic mild stress and hyperlipidic/ hyper caloric diet-group IV. The second experiment was similar with the first but the rats received Agomelatine (0.16mg/ animal): group V (depression induced through exposure to chronic mild stress), VI (depression induced through olfactory bulbectomy) and VII (depression induced through exposure to chronic mild stressing hyperlipidic/ hypercaloric diet). Weight, cholesterol, triglycerides and glycaemia were measured at day 0 and 28, and leptin value was measured at day 28. The results in the 1st experiment revealed significant differences (pconclusion, significant correlations were found between high level of triglycerides and depression induced by chronic stress and olfactory bulbectomy. Agomelatine groups had a lower increase of triglycerides levels
Theory for the phase behaviour of a colloidal fluid with competing interactions
We study the phase behaviour of a fluid composed of particles which interact
via a pair potential that is repulsive for large inter-particle distances, is
attractive at intermediate distances and is strongly repulsive at short
distances (the particles have a hard core). As well as exhibiting gas-liquid
phase separation, this system also exhibits phase transitions from the uniform
fluid phases to modulated inhomogeneous fluid phases. Starting from a
microscopic density functional theory, we develop an order parameter theory for
the phase transition in order to examine in detail the phase behaviour. The
amplitude of the density modulations is the order parameter in our theory. The
theory predicts that the phase transition from the uniform to the modulated
fluid phase can be either first order or second order (continuous). The phase
diagram exhibits two tricritical points, joined to one another by the line of
second order transitions.Comment: 12 pages, 9 figures. Accepted for publication in J. Phys. Condens.
Matte
Gas Geochemistry and Fractionation Processes in Florina Basin, Greece
Florina Basin is located in northern Greece, close to Mount Voras where the volcanic activity of Late Messinian age began. In the area, many CO2-rich gas emissions are present as a bubbling free-phase in groundwater (both springs and wells) and soil gases. Volcanism along with the geological and geodynamic regime of the basin, created the ideal conditions for CO2 accumulation in vertically stacked reservoirs. One of these, industrially exploited by the company Air Liquide Greece, produces 30,000 t/a of CO2. Results show that CO2 concentrations in the gases of Florina can arrive up to 99.8% and are mostly above 90%. Moreover, C-isotope composition (-2.1 to + 0.3 h vs. VPDB) indicates a mixed mantle-limestone origin for CO2, while He isotope composition (R/RA from 0.21 to 1.20) shows a prevailing crustal origin with an up to 15% mantle contribution. Helium and methane, with concentrations spanning over three orders of magnitude, show a positive correlation and a consequent high variability of He/CO2 and CH4/CO2 ratios. This variability can be attributed to the interaction of the uprising gases with groundwater that chemically fractionates them due to their different solubility. Based on the CO2, CH4 and He concentrations, gas samples collected in the basin can be divided in 3 groups: a) deep reservoir gases, b) enriched in less soluble gases and c) depleted in less soluble gases. The first group consists of gas samples collected at the Air Liquide extraction wells, which tap a 300m deep reservoir. This group can be considered as the least affected by fractionation processes due to interaction with groundwater. The gases of the second group due to their interaction with shallower unsaturated aquifers, become progressively enriched in less soluble gases (He and CH4). Finally, the third group represents residual gas phases after extensive degassing of the groundwater during its hydrological pathway
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