A study of the age, growth, sexual maturity, and spawning of the anchoveta, Cetengraulis mysticetus, in the Gulf of Panama

ENGLISH: Crew members of tuna clippers and Commission personnel are collecting specimens of anchovetas (Cetengraulis mysticetus) for studies of the biology of this important tuna-bait species. More than 27,000 fish from 231 collections captured in the Gulf of Panama between June 1951 and January 1956 are the basis of this study of the age, growth, sexual maturity, and spawning season of this species in that area. Estimates of age and rate of growth were made by studying the temporal progression of modal size groups from monthly length frequency distributions. Sexual development and time of spawning were determined from gross examination of ovaries and measurements of ovarian eggs. SPANISH: Con el fin de estudiar la biología de la anchoveta (Cetengraulis mysticetus) los tripulantes de los barcos atuneros y el personal de la Comisión están recolectando especimenes de esta importante especie de carnada para capturar el atún. Mas de 27,000 ejemplares de las 231 colecciones hechas en el Golfo de Panamá entre junio de 1951 y enero de 1956, sirven de material al presente estudio sobre la edad, el crecimiento, la madurez sexual y las épocas de desove de esta especie en el área indicada. Las estimaciones de la edad y de la proporción del crecimiento fueron hechas a base del estudio de la progresión temporal de los grupos modales de tamaño en las distribuciones mensuales de frecuencias de longitud. El desarrollo sexual y el periodo de desove fueron determinados mediante el examen microscópico de los ovarios y las mediciones de los huevos ováricos. (PDF contains 79 pages.

Changes in the dynamical behavior of nonlinear systems induced by noise.

Weak noise acting upon a nonlinear dynamical system can have far-reaching consequences. The fundamental underlying problem - that of large deviations of a nonlinear system away from a stable or metastable state, sometimes resulting in a transition to a new stationary state, in response to weak additive or multiplicative noise - has long attracted the attention of physicists. This is partly because of its wide applicability, and partly because it bears on the origins of temporal irreversibility in physical processes. During the last few years it has become apparent that, in a system far from thermal equilibrium, even small noise can also result in qualitative change in the system's properties, e.g., the transformation of an unstable equilibrium state into a stable one, and vice versa, the occurrence of multistability and multimodality, the appearance of a mean field, the excitation of noise-induced oscillations, and noise-induced transport (stochastic ratchets). A representative selection of such phenomena is discussed and analyzed, and recent progress made towards their understanding is reviewed

Development of turbulence in submerged jets as a noise-induced transition

Experiments show that the amplitude of turbulent pulsation in submerged jets rises with increasing distance from the nozzle, at first slowly and then, after a certain distance, rapidly. This dependence on distance from the nozzle closely resembles the dependence of an order parameter on temperature in the case of a second-order phase transition. Following an idea introduced by Landa and Zaikin in 1996, it is suggested that the onset of turbulence is a noise-induced phase transition similar to that in a pendulum with a randomly vibrated suspension axis. The Krylov-Bogolyubov asymptotic method is used to provide an approximate description of the transition. Results obtained in this way are shown to coincide closely with experimental data. Such an approach is appropriate because the convective character of the instability means that turbulence in nonclosed flows cannot be a self-oscillatory process, as is often assumed. Rather, it must originate in the external random disturbances that are always present in real flows

Nonlinear dynamics of coupled transverse-rotational waves in granular chains

The nonlinear dynamics of coupled waves in one-dimensional granular chains with and without a substrate is theoretically studied accounting for quadratic nonlinearity. The multiple time scale method is used to derive the nonlinear dispersion relations for infinite granular chains and to obtain the wave solutions for semiinfinite systems. It is shown that the sum-frequency and difference-frequency components of the coupled transverse-rotational waves are generated due to their nonlinear interactions with the longitudinal wave. Nonlinear resonances are not present in the chain with no substrate where these frequency components have low amplitudes and exhibit beating oscillations. In the chain positioned on a substrate two types of nonlinear resonances are predicted. At resonance, the fundamental frequency wave amplitudes decrease and the generated frequency component amplitudes increase along the chain, accompanied by the oscillations due to the wave numbers asynchronism. The results confirm the possibility of a highly efficient energy transfer between the waves of different frequencies, which could find applications in the design of acoustic devices for energy transfer and energy rectification

Modes of Oscillation in Radiofrequency Paul Traps

We examine the time-dependent dynamics of ion crystals in radiofrequency traps. The problem of stable trapping of general three-dimensional crystals is considered and the validity of the pseudopotential approximation is discussed. We derive analytically the micromotion amplitude of the ions, rigorously proving well-known experimental observations. We use a method of infinite determinants to find the modes which diagonalize the linearized time-dependent dynamical problem. This allows obtaining explicitly the ('Floquet-Lyapunov') transformation to coordinates of decoupled linear oscillators. We demonstrate the utility of the method by analyzing the modes of a small `peculiar' crystal in a linear Paul trap. The calculations can be readily generalized to multispecies ion crystals in general multipole traps, and time-dependent quantum wavefunctions of ion oscillations in such traps can be obtained.Comment: 24 pages, 3 figures, v2 adds citations and small correction

Phase transitions and spin-state of iron in FeO at the conditions of Earth's deep interior

Iron-bearing oxides undergo a series of pressure-induced electronic, spin and structural transitions that can cause seismic anomalies and dynamic instabilities in Earth's mantle and outer core. We employ x-ray diffraction and x-ray emission spectroscopy along with state-of-the-art density functional plus dynamical mean-field theory (DFT+DMFT) to characterize the electronic structure and spin states, and crystal-structural properties of w\"ustite (Fe$_{1-x}$O) -- a basic oxide component of Earth's interior -- at high pressure-temperature conditions up to 140 GPa and 2100 K. We find that FeO exhibits complex polymorphism under pressure, with abnormal compression behavior associated with electron-spin and crystallographic phase transitions, and resulting in a substantial change of bulk modulus. Our results reveal the existence of a high-pressure phase characterized by a metallic high-spin state of iron at about the pressure-temperature conditions of Earth's core-mantle boundary. The presence of high-spin metallic iron near the base of the mantle can significantly influence the geophysical and geochemical properties of Earth's deep interior.Comment: 5 figures, with supplementary material

Peculiarities of the formation and subsequent removal of the circulating immune complexes from the bloodstream during the process of digestion [version 1; referees: 2 approved, 1 approved with reservations]

Background: Large protein aggregates, known as circulating immune complexes (CICs), are formed in biological fluids as a result of the development of the body's immune response to various provoking factors. The kinetic characteristics of the formation and removal of immune complexes (ICs), their physical parameters, the isotypic composition of immunoglobulins (Igs) and the antigenic component of the CICs may reflect certain aspects of certain pathological and metabolic processes taking place in humans and animals. The aim of this study is to assess the kinetic characteristics of the formation and removal of the CICs that form in blood after eating. We also analyze the changes in the isotypic composition of Igs of ICs that accompany this biological process in rodents and humans. Methods: We identified the CICs, which differed in size and class of Igs, using dynamic light scattering. To remove ICs from the plasma, we used immune-affinity sedimentation. Monoclonal antibodies for the Igs of different isotypes were added to the plasma samples to determine the isotypic composition of the ICs. Results: A large number of ICs were formed in the blood of rats and humans after eating (food CICs). In rats, food ICs are almost immediately filtered in the liver, without circulating in the bloodstream through the body. In humans, the level of food ICs in the blood increases for 3.5 h after ingestion, then within 7–8 h their gradual removal takes place. It was found that in the process of digestion in humans, the isotypic composition of Igs in the CICs changes and becomes more diverse. Conclusions: The molecular–cellular mechanisms of the formation and utilization of food CICs in humans and rodents do not match completely