Effects of Pesticides on Aquatic Fauna: A Literature Review

The excessive use of pesticides produced by agriculture, industry and anthropic activities generates negative effects on the environment and human beings. These chemical substances reach rivers and lakes through runoff or leaching and groundwater through infiltration. The objective of this study was to identify the effects caused by pesticides on aquatic fauna through a bibliographic review in order to provide recommendations for improvement and future surveys. The methodology used was based on a bibliographic review that subsequently allowed the information collected to be analyzed and presented in tables and arguments to propose recommendations for improvement. The main results indicate that in aquatic biota, pesticides reduce phytoplankton, cause problems in the functioning of aquatic species and in the worst case a decrease in the population. On the other hand, humans are also affected through the consumption of contaminated species. Finally, the study concludes by considering that the reduction and adequate management of pesticides can be carried out through the replacement of pesticides by the chemical substance produced by garlic, social awareness, regulatory policies that are applicable, monitoring and evaluation that allow obtaining information to subsequently generate alternatives for improvement against pesticide contamination. Keywords: ecotoxicology, aquatic ecosystem, pollution, aquatic species, pesticide. Resumen El uso desmedido de plaguicida producto de la agricultura, industria y actividades antrópicas generan efectos negativos sobre el ambiente y el ser humano. Estas sustancias químicas llegan a los ríos y lagos por la escorrentía o lixiviación y a las aguas subterráneas por infiltración. El objetivo de este estudio se centró en identificar los efectos causados por los plaguicidas sobre la fauna acuática mediante revisión bibliográfica para conferir recomendaciones de mejora y prospecciones futuras. La metodología utilizada se basó en una revisión bibliográfica que posteriormente permitió analizar la información recolectada y presentarla mediante tablas y argumentos para proponer recomendaciones de mejora. Los principales resultados indican que en la biota acuática los plaguicidas disminuyen el fitoplancton, producen problemas en el funcionamiento de las especies acuáticas y en el peor de los casos una disminución en la población. Por otro lado, el ser humano también se encuentra afectado mediante el consumo de las especies contaminadas. Finalmente, el estudio concluye considerando que la reducción y adecuada gestión de plaguicidas se puede llevar a cabo mediante reemplazo de plaguicidas por la sustancia química producida por el ajo, concientización social, políticas de regulación que sean aplicables, monitoreo y evaluación que permitan la obtención de información para posteriormente generar alternativas de mejora frente a la contaminación por plaguicidas. Palabras Clave: ecotoxicología, ecosistema acuático, contaminación, especies acuáticas, plaguicida

5-State Rotation-Symmetric Number-Conserving Cellular Automata are not Strongly Universal

We study two-dimensional rotation-symmetric number-conserving cellular automata working on the von Neumann neighborhood (RNCA). It is known that such automata with 4 states or less are trivial, so we investigate the possible rules with 5 states. We give a full characterization of these automata and show that they cannot be strongly Turing universal. However, we give example of constructions that allow to embed some boolean circuit elements in a 5-states RNCA

Resonant x-ray scattering study on multiferroic BiMnO3

Resonant x-ray scattering is performed near the Mn K-absorption edge for an epitaxial thin film of BiMnO3. The azimuthal angle dependence of the resonant (003) peak (in monoclinic indices) is measured with different photon polarizations; for the $\sigma\to\pi'$ channel a 3-fold symmetric oscillation is observed in the intensity variation, while the $\sigma\to\sigma'$ scattering intensity remains constant. These features are accounted for in terms of the peculiar ordering of the manganese 3d orbitals in BiMnO3. It is demonstrated that the resonant peak persists up to 770 K with an anomaly around 440 K; these high and low temperatures coincide with the structural transition temperatures, seen in bulk, with and without a symmetry change, respectively. A possible relationship of the orbital order with the ferroelectricity of the system is discussed.Comment: 14 pages, 4 figure

Seasonal variations of the vagile fauna associated with Ectopleura crocea (Cnidaria, Hydrozoa) in El Rompido marina (Huelva)

El desarrollo urbano en las zonas costeras se ha visto incrementado notablemente en los últimos años, resultando en un mayor número de estructuras artificiales en los ambientes marinos. Diversos organismos han sido capaces de colonizar las superficies de estos nuevos hábitats, incluyendo al hidrozoo Ectopleura crocea (Agassiz, 1862). Se estudió la epifauna asociada a esta especie a lo largo de un año en Puerto Marina, El Rompido, Huelva, con el objetivo de describir su composición y fluctuaciones temporales. En total, se encontraron 22 especies, mayoritariamente crustáceos anfípodos, siendo los más abundantes Stenothoe tergestina (Nebeski, 1881) y Apocorophium acutum (Chevreux, 1908). No se encontraron diferencias significativas a lo largo del ciclo anual en los valores de abundancia y diversidad, si bien se detectaron cambios en la composición faunística. En general, la diversidad de especies encontrada en Ectopleura crocea fue menor que la citada en otros estudios en hábitats naturales. Se sugiere que ello puede ser debido a características intrínsecas del hábitat artificial, tales como una menor heterogeneidad de sus superficies o a un mayor estrés ambiental. Por ello, para contrastar la consistencia a lo largo del tiempo y la causa de tales patrones, sería necesario estudios futuros que abarcasen un mayor rango temporal.Urban development in coastal areas has increased considerably in recent years, which has resulted in a larger number of artificial structures in coastal marine environments. However, various organisms have been able to colonize the surfaces of these new habitats, including the hydrozoan Ectopleura crocea (Agassiz, 1862). We studied the epifauna associated with this species over a year in Puerto Marina, El Rompido, Huelva, with the objective of describing its composition and temporal fluctuations. In total, 22 species were found, mostly amphipod crustaceans, the most abundant of these being Stenothoe tergestina (Nebeski, 1881) and Apocorophium acutum (Chevreux, 1908). No significant differences were found between the abundance and diversity of epifauna throughout the year, although changes in epifauna composition were detected over time. In general, the diversity found on Ectopleura crocea in the present study was lower than that reported by other studies in natural habitats. It is suggested that this could be due to intrinsic characteristics of the artificial habitat, such as lower heterogeneity of its surfaces or greater environmental stress. To contrast consistency over time and the causes of these patterns future studies carried out over a larger time period will be necessar

Thermodynamic potential with correct asymptotics for PNJL model

An attempt is made to resolve certain incongruities within the Nambu - Jona-Lasinio (NJL) and Polyakov loop extended NJL models (PNJL) which currently are used to extract the thermodynamic characteristics of the quark-gluon system. It is argued that the most attractive resolution of these incongruities is the possibility to obtain the thermodynamic potential directly from the corresponding extremum conditions (gap equations) by integrating them, an integration constant being fixed in accordance with the Stefan-Boltzmann law. The advantage of the approach is that the regulator is kept finite both in divergent and finite valued integrals at finite temperature and chemical potential. The Pauli-Villars regularization is used, although a standard 3D sharp cutoff can be applied as well.Comment: 16 pages, 5 figures, extended version, title change

Low-density series expansions for directed percolation IV. Temporal disorder

We introduce a model for temporally disordered directed percolation in which the probability of spreading from a vertex $(t,x)$, where $t$ is the time and $x$ is the spatial coordinate, is independent of $x$ but depends on $t$. Using a very efficient algorithm we calculate low-density series for bond percolation on the directed square lattice. Analysis of the series yields estimates for the critical point $p_c$ and various critical exponents which are consistent with a continuous change of the critical parameters as the strength of the disorder is increased.Comment: 11 pages, 3 figure

Utilización de redes neuronales para formular grasas técnicas

Neural networks are a branch of artificial intelligence based on the structure and development of biological systems, having as its main characteristic the ability to learn and generalize knowledge. They are used for solving complex problems for which traditional computing systems have a low efficiency. To date, applications have been proposed for different sectors and activities. In the area of fats and oils, the use of neural networks has focused mainly on two issues: the detection of adulteration and the development of fatty products. The formulation of fats for specific uses is the classic case of a complex problem where an expert or group of experts defines the proportions of each base, which, when mixed, provide the specifications for the desired product. Some conventional computer systems are currently available to assist the experts; however, these systems have some shortcomings. This article describes in detail a system for formulating fatty products, shortenings or special fats, from three or more components by using neural networks (MIX). All stages of development, including design, construction, training, evaluation, and operation of the network will be outlined.Las redes neuronales son una rama de la inteligencia artificial basadas en la estructura y funcionamiento de sistemas biológicos, teniendo como principal característica la capacidad de aprender y generalizar conocimiento. Estas son utilizadas en la resolución de problemas complejos, en los cuales los sistemas computacionales tradicionales presentan una eficiencia baja. Hasta la fecha, han sido propuestas aplicaciones para los más diversos sectores y actividades. En el área de grasas y aceites, la utilización de redes neuronales se ha concentrado principalmente en dos asuntos: la detección de adulteraciones y la formulación de productos grasos. La formulación de grasas para uso específico es el caso clásico de problema complejo donde un experto o grupo de expertos definen las proporciones de cada base, que al ser mezcladas proporcionaran características especificadas para el producto deseado. Algunos sistemas computacionales convencionales están disponibles actualmente para auxiliar a los expertos, sin embargo, estos sistemas presentan algunas deficiencias. En este artículo será descrito con detalles, un sistema para la formulación de productos grasos por redes neuronales (MIX) a partir de 3 o más componentes. Todas las etapas del desarrollo, incluyendo el diseño, construcción, entrenamiento, evaluación y operación de la red serán mostradas

Stabilization of heterodimensional cycles

We consider diffeomorphisms $f$ with heteroclinic cycles associated to saddles $P$ and $Q$ of different indices. We say that a cycle of this type can be stabilized if there are diffeomorphisms close to $f$ with a robust cycle associated to hyperbolic sets containing the continuations of $P$ and $Q$. We focus on the case where the indices of these two saddles differ by one. We prove that, excluding one particular case (so-called twisted cycles that additionally satisfy some geometrical restrictions), all such cycles can be stabilized.Comment: 31 pages, 9 figure