On the Coriolis Effect for Internal Ocean Waves

A derivation of the Ostrovsky equation for internal waves with methods of the Hamiltonian water wave dynamics is presented. The internal wave formed at a pycnocline or thermocline in the ocean is influenced by the Coriolis force of the Earth's rotation. The Ostrovsky equation arises in the long waves and small amplitude approximation and for certain geophysical scales of the physical variables.

Vibration Analysis of Cylindrical with Splitter Plates under Different Deflection Angles at High Reynolds Number

In order to study the influence of the splitter plate in the elastic support system, the SST k-omega turbulence model is used to solve the problem, and the cylindrical system with splitter plate is numerically simulated by overset mesh. This paper studies the effect of the splitter plate on the vibration system at different deflection angles. The results show that the splitter plate has little effect on the system when the deflection angle is low. When the deflection angle is about 10 degrees, the system vibration characteristics will have a sudden change, the amplitude will decrease, and the vortex frequency will increase. Between the deflection angle of 10 degrees and 45 degrees, as the deflection angle increases, the amplitude increases and the vortex frequency decreases. It can be seen from the motion trajectory that the deflection angle changes suddenly after 10 degrees, and the system has a very small amplitude between 10 degrees and 25 degrees. In this declination interval, the splitter plate controls the vibration of the cylindrical system better.

The "disease of the crazy hatman" and the effects of human exposure to mercury: A case report / A "doença do homem do chapéu maluco" e os efeitos da exposição humana ao mercúrio: Um relato de caso

INTRODUCTION: Mercury, in addition to being a heavy metal, is considered a neurotoxin, that is, a substance capable of negatively affecting the neurological functions of the human body. Nowadays, ““Mad Hatter's Disease”” is the name used to characterize these neurological disorders caused by mercury. PURPOSE: to report a clinical case of the manifestation of “Mad Hatter's Disease”, as well as to discuss about the effects of human exposure to mercury. METHODOLOGY: this is a clinical case report, in which the patient is essential. CASE REPORT: A 45-year-old male patient, gold miner, from a riverside community in the Amazon, was referred to the hospital with complaints of headache, extremities tremor, diarrhea, tiredness, discouragement, irritability, depression, unusual shyness and hallucinations. On physical examination, the patient was anxious, irritable, symmetrical small-amplitude tremors in the extremities, hyperreflexia ++/4+ in the upper limbs, +/4+ in the lower limbs, normal muscle strength, mild ataxia of the right hand, stained skin and mucous membranes, and acyanotic, with erythematous-scaly lesions, confluent on the trunk, palms and soles of the feet. Screening for mercury poisoning was performed, where it was found, both in blood and urine, the presence of mercury 20 times above the biological tolerance limit. A battery of specific neuropsychological tests was carried out in neurotoxicological assessments and these demonstrated impairment of the cognitive domains (deficit of memory, attention, concentration, reasoning and abstraction) and alterations in motor functions, showing reduced coordination and motor speed. The diagnosis of hydrargyrism or occupational chronic metallic mercuralism (MMCO) was given. DISCUSSION: Chronic occupational exposure to inorganic mercury can cause subclinical abnormalities, as well as long-term psychomotor and neuromuscular behavioral impairment. Neuropsychiatric abnormalities (inattention, memory, interpretation, and motor performance) appear to be dose-related. FINAL CONSIDERATIONS: chronic exposure to metallic mercury vapor characteristically compromises the nervous system, initially with nonspecific symptoms and, later, with characteristic motor disorders - small amplitude tremor, paresis, dysreflexia and difficulty in motor coordination, which gives rise to the "Disease of the Mad Hatter”, and inhaling large amounts of mercury vapor can be lethal.

Limit Cycles from Hopf Bifurcation in Nongeneric Quadratic Reversible Systems with Piecewise Perturbations

In this paper, we consider a nongeneric quadratic reversible system with piecewise polynomial perturbations. We use the expansion of the first order Melnikov function to obtain the maximal number of small-amplitude limit cycles produced by Hopf bifurcation in the perturbed systems.

Periodically kicked feedforward chains of simple excitable FitzHugh-Nagumo neurons

This article communicates results on regular depolarization cascades in periodically-kicked feedforward chains of excitable two-dimensional FitzHugh-Nagumo systems driven by sufficiently strong excitatory forcing at the front node. The study documents a parameter exploration by way of changes to the forcing period, upon which the dynamics undergoes a transition from simple depolarization to more complex behavior, including the emergence of mixed-mode oscillations. Both rigorous studies and careful numerical observations are presented. In particular, we provide rigorous proofs for existence and stability of periodic traveling waves of depolarization, as well as the existence and propagation of a simple mixed-mode oscillation that features depolarization and refraction in alternating fashion. Detailed numerical investigation reveals a mechanism for the emergence of complex mixed-mode oscillations featuring a potentially high number of large amplitude voltage spikes interspersed by an occasional small amplitude reset that fails to cross threshold. Further careful numerical investigation provides insights into the propagation of this complex phenomenology in the downstream, where we see an effective filtration property of the network; the latter amounts to a successive reduction in the complexity of mixed-mode oscillations down the chain.

DIAGNOSIS OF SEMICONDUCTOR HETEROSYSTEMS USING THE PHOTOVOLTAIC METHOD

The diagnostic method is as follows: the lateral photo-EMF spectral characteristics are measured, generated in the structure (or device) when illuminated by wavelength light with a near the edge of the basic semiconductor layer. For illustrations of efficiency method the given part of the measurement results for Schottky contact samples with a nitrogen concentration of 5% and a thermal annealing temperature of 900 and 950°C. It has been found that a significant character and a small amplitude of such a characteristic indicates qualitative at a homogeneity and the necessary magnitude of the potential barrier (or barriers), that it is necessary to form to make Schottky contact or other structure. A significant characteristic and a small amplitude of such a characteristic indicates a qualitative one-line and the required value of a potential barrier (or barriers) that must be formed for the manufacture of a semiconductor structure or device. If the spectral characteristic has one maximum and amplitude that is many times higher than the amplitude of a significant characteristic, then this indicates a formed transition layer between components of heterosystems with high, compared with a quasine-power region of semiconductor, conductivity. The presence of such a layer increases the probability breaks down of the microelectronic device. Investigation of the distribution of lateral photours along the metal semiconductor interface compliant interpretation of spectral characteristics features. The linear significant form of distribution of EMF confirms the presence of a transition layer with a lower doping level compared with GaAs. An important feature of the diagnostic method is its non-destructive character, as well as the possibility of applying to semiconductor or devices based on them, in which the photovoltaic effect may occur.

Damped shape oscillations of a viscous compound droplet suspended in a viscous host fluid

A study of small-amplitude shape oscillations of a viscous compound droplet suspended in a viscous host fluid is performed. A generalized eigenvalue problem is formulated and is solved by using the spectral method. The effects of the relevant non-dimensional parameters are examined for three cases, i.e. a liquid shell in a vacuum and a compound droplet in a vacuum or in a host fluid. The fundamental mode $l=2$ is found to be dominant. There exist two oscillatory modes: the in phase and the out of phase. In most situations, the interfaces oscillate in phase rather than out of phase. For the in-phase mode, in the absence of the host, as the viscosity of the core or the shell increases, the damping rate increases whereas the oscillation frequency decreases; when the viscosity exceeds a critical value, the mode becomes aperiodic with the damping rate bifurcating into two branches. In addition, when the tension of the inner interface becomes smaller than some value, the in-phase mode turns aperiodic. In the presence of the unbounded host fluid, there exists a continuous spectrum. The viscosity of the host may decrease or increase the damping rate of the in-phase mode. The mechanism behind it is discussed. The density contrasts between fluids affect oscillations of the droplet in a complicated way. Particularly, sufficiently large densities of the core or the host lead to the disappearance of the out-of-phase mode. The thin shell approximation predicts well the oscillation of the compound droplet when the shell is thin.