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.

Efficiency in Finacial Regulation and Reform of Supervisory

Traditionally, the financial regulation it used to structure itself on the basis of specialized organizations, each one responsible to supervise the intermediaries by the type of activity that was carried out. The current trend is toward an integrated model that reunite in one or two organizations the different functions that previously were responsibility of diverse specialized authorities. From the modern theory of economic regulations it is possible to assess a regulatory regimen by how close is to address the market failures on the market supposed to regulated and how minimal is the social cost it imposed over its regulated entities and the market as a whole. A regulatory regime of fragmented supervisory authorities increases the risk of regulatory failures therefore not always capable to exploit the economies of scale and scope in a regulatory task intensive in opportune information gathering and processing, also exposed to regulatory forbearance and becoming interest groups by themselves. In fact, becoming each regulator a monopoly over its regulated entities, creating rents by protecting a turf of captive supervisory powers incompatible and unsynchronized with each other. Therefore, incrementing the cost of regulation. Considering the cost of regulation as a fixed cost on each domestic financial market. An efficient setting would be a low fixed cost relative to a high sized financial market. The relative performance efficiency between the multiple regulatory agencies model and the single regulator model is empirically an open question, despite of the international spread of the single model in the last decade in more than ten countries. Low income countries with severe underdeveloped financial markets and costly multiple authorities scheme calls for a prime candidates to reform its financial regulatory. Using indicators from supervisory cost and financial activity size, Mexico appears to be the economy with the highest fixed cost in an underdeveloped or small size financial activity relative to the GDP therefore, it means a highly inefficient regulatory organization. Urgent supervisory institutional scheme reform is required according with international benchmarks.Banking Regulation, Prudential Regulation, Regulatory Failures

Multistability of Driven-Dissipative Quantum Spins

We study the dynamics of lattice models of quantum spins one-half, driven by a coherent drive and subject to dissipation. Generically the meanfield limit of these models manifests multistable parameter regions of coexisting steady states with different magnetizations. We introduce an efficient scheme accounting for the corrections to meanfield by correlations at leading order, and benchmark this scheme using high-precision numerics based on matrix-product-operators in one- and two-dimensional lattices. Correlations are shown to wash the meanfield bistability in dimension one, leading to a unique steady state. In dimension two and higher, we find that multistability is again possible, provided the thermodynamic limit of an infinitely large lattice is taken first with respect to the long time limit. Variation of the system parameters results in jumps between the different steady states, each showing a critical slowing down in the convergence of perturbations towards the steady state. Experiments with trapped ions can realize the model and possibly answer open questions in the nonequilibrium many-body dynamics of these quantum systems, beyond the system sizes accessible to present numerics

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