Search

A trophic study was carried out in February of 2012 to January 2013 on the ecosystem in the Persian Gulf, Bushehr provience. A total of 2,948 samples of stomach contents were analyzed based on the weight and number of food items and were identified about 40 preys. Crustacean and bony fish were as a main prey in most of the stomach contents .The mean average trophic level was estimated at 3.6 by Ecopath software. In this research, the mean level were studied between eight species varied from 3.47 to 4.61, Saurida tumbil occupy the highest and the Argyrops spinifer was the lowest level.The ranges of total mortality varied from 0.7 to 3.05 per years. The food consumption rate was estimated about 69.82 per year. The overlap index showed that the prey items such as fish, crustacean, bivalve and echinoderm were shared about 65, 15, 15 and 6 percent in all stomach of individual in respectively. Mixed trophic analysis indicates that benthos have a positive effect on most of the fish species. Most species have a negative impact on themselves, interpreted here as reflecting increased with in group competition for resources. This preliminary model can be helpful to determine the gaps in the present knowledge about demersal system of the Persian Gulf. PhD Thesis Advisors: S.M.R. Fatemi p.h.D. and F.Kaymaram p.h.D. Consulting Advisors: S.A.A taghavi motlagh p.h.D. and T. Valinasab p.h.D.

In the present study, length structure, mortality and exploitation rate of Otolithes ruber during a ten-year period were studied. Sampling was carried out by using bottom trawl net in the fishing area in Northwest of Persian Gulf over 1 year study period. Length data was also collected from fisheries research institute and fishery organization. Age determination was done by reading annual rings on sectioned otolith. Growth parameters were calculated based on age and length data. These data were used to estimate natural mortality rate. Total mortality was obtained from the age curve. Logarithmic catch and natural mortality were calculated from Pauly's equation. The averages of length in the last ten years were 35 to 39 cm. The samples ranged in length from 12 to 58 cm with the maximum frequencies between 28-44 cm. Length distribution was normal in this study. The maximum catch was composed of fish in the 40 to 48 cm length range with an average age of 2 to 3 years. The average total mortality, natural mortality and fishing mortality were 0.98, 0.56, and 0.42 respectively. Mortality was higher in age group 0 and age group 1, but mortality of the other age groups dramatically decreased. Exploitation rate in the last ten years were 0.42 indicating a near complete exploitation. Based on the results a more effective exploitation strategy is suggested in this region.

Effect of transportation of rainbow trout gametes under moist oxygen packing at 1-2 °c on fertilization was studied. Gametes were transferred in polyethylene bags (20×18 cm) containing 0, 25, 50, 75 and 100 % moist oxygen (in its free volume) and ten hours after transfer in a Styrofoam box with thermo gel bags, fertilization were conducted in 25 treatments (in 3 replicates) and fertilized eggs were transferred to an incubator designed for rainbow trout with recirculation system (10°c). Percentage of fertility, eyed eggs, and hatching rate were calculated as an indicator for determination of optimum level of oxygen during transportation. The best results were obtained from fertilization of eggs transported at 100% oxygen and sperm transported at 75% oxygen with 95.01 ± 1.2% fertility, 78±4.21% eyed eggs and 75±3.88% hatching rate which were significant different (p

Neste artigo, investigamos e analisamos obstáculos em relação à aplicação da modelagem matemática no cotidiano da sala de aula. Tais obstáculos foram apontados pelos professores recém-formados, egressos de cursos de licenciatura em Matemática em universidades públicas do Estado do Paraná e que cursaram a disciplina de Modelagem Matemática na graduação. A opção metodológica da investigação foi a Análise Textual Discursiva. Os dados foram obtidos por meio das respostas a um questionário respondido por 15 professores que lecionam na educação básica deste estado. Os obstáculos apontados por esses professores estão contemplados em três categorias: (i) formação insuficiente em modelagem matemática, bem como nos conteúdos a ministrar; (ii) dificuldades em aplicar a modelagem devido à postura tradicional e conservadora do sistema escolar e (iii) dificuldades em envolver os estudantes num ambiente de modelagem matemática. Essas categorias evidenciam que a modelagem matemática sofre resistências quanto a sua aplicação na sala de aulae que tais resultados podem contribuir para discussões sobre aformação de professores de Matemática.

Presence of each pollution and changing in the marine ecosystem have sever impacts on Biotic factors and economic ecological potential in this valuable area. Thus, ecological health monitoring to evaluation of habitat health are important.In this study, AMBI(Azti Marine Biology Index) was used to evaluation health of Bahrakan coastal area as a main fisheries and petroleum extraction ground. The results showed studied area classified in good ecological status. The dominance species was from Ophiuridae family with ecological group II. Based on richness and diversity index value, studied areas are classified in bad ecological status. This result discordantly can cause due to differences in influences variable. Low rate of water exchange, high degree of temperature and salinity maybe were lead to decreasing in macrobenthic richness and diversity index values but AMBI result that get from ratio between sensitive and resistant species, shows good ecological status.

In order to study concentration of polycyclic aromatic hydrocarbons in seawater from Bushehr coast and for comparison with available guidelines samples of seawater were collected from five different stations along the Bushehr coast in August and February 2011. PAHs were extracted by Hexane solvent and analyzed using HPLC system (Knauer). Results showed that tPAHs concentration in seawater were 31.0, 20.8, 4.0, 17.6 and 12.3 µg l-1, in August and 38.4, 23.0, 5.4, 19.3 and 17.2 µg l-1 in February respectively, at stations Rafael, Sheghab, Abshirinkon, Lian and Helyleh. The concentrations of tPAHs in the seawater were not significantly different during August and February (P>0.05). Significant difference was observed between tPAHs concentration between the stations (P

A partir da interrogação: Quais as contribuições do estágio de docência para a formação de professores em Modelagem Matemática? Este relato busca apresentar reflexões sobre experiência vivida durante esse período e os aspectos que dela emergiram. Pudemos compreender que a visão teórica se articula com a prática, mostrando que estas coexistem em um mesmo ambiente, proporcionando reflexões a respeito das diferentes abordagens nas práticas envolvendo modelagem matemática. O papel do orientador em nossa experiência desvela-se extremamente significativo, tal como o rompimento de pré-conceitos a respeito da disciplina de Matemática. Além disso, sinaliza para diferentes posturas que nós, como professores, deveremos empreender em sala de aula. O relato aqui descrito ilumina a visão a respeito do estágio docente, propondo reflexões e mudanças na postura profissional dos professores em formação inicial ou continuada, bem como proporciona discussões sobre a formação continuada de professores em Modelagem.

Effect of salinity levels on density and population growth of parthenogenetic Artemia were studied. Cysts were hatched and 200 nauplii were transferred into cylindro-conical containers (1.5 liter) containing one-liter water at different salinities (50, 100, 150, 200 and 250 ppt) and cultured until maturity. After maturity, 3 female parthenogenetic Artemia wereselected randomly from each of the five levels of salinity and cultured in 4 replicates for 12 weeks. The growing Artemia were categorized into four population groups (1) nauplii and meta-nauplii, (2) juvenile Artemia (3) pre-adult Artemia, and (4) adult Artemia and were counted once a week. Results showed that the density of adults, nauplii and meta-nauplii were higher in 100 ppt. The maximum population of pre-adult and juvenile Artemia were found at 50 ppt. The density of adult Artemia increased while density of other categories decreased during culture period. Based on our findings, an inverse relationship between salinity and population of parthenogenetic Artemia were observed. Results indicated that lower salinities are more suitable for population growth of parthenogenetic Artemia.

Neste artigo, objetiva-se compreender a percepção e expressão de modelagem matemática de sessenta e três professores de matemática da educação básica. Apresentam-se resultados da pesquisa aplicada, cujos dados empíricos foram obtidos em Curso de formação continuada de modelagem matemática de dezesseis horas, divididas em dois encontros. Os dados advindos da observação e dos registros de questionamentos e discussões, ocorridas no início do segundo encontro, foram analisados por meio da análise do discurso, com aporte na neurociência - memória. Compreendeu-se que esses professores expressam, ao evocarem a memória na forma de redes, as etapas da modelagem matemática diferentemente da ordem trabalhada. A expressão de modelagem por meio de redes, construídas a partir da memória alvo, o tema, evidenciou, inicialmente, o modelo obtido e, na sequência, a etapa desse modelo. A partir dele, expressaram uma rede semântica que conduz constantemente a outras etapas da modelagem matemática.

En modelación, los estudiantes se sienten motivados a buscar patrones, asumir regularidades, desarrollar y contrastar ideas, así como a dar razones o argumentos si ellos reconocen la necesidad de disponer de un modelo para la solución de un problema. Para que los estudiantes aprendan a modelar situaciones matemáticamente y a usar técnicas estadísticas y soporte informático para analizar modelos, las actividades deben ser seleccionadas de tal manera que, por aproximaciones sucesivas, obtengan la mejor respuesta o la más aproximada a las condiciones planteadas. El trabajo con modelos será exitoso en la medida que los estudiantes sean capaces de abstraer el modelo de las situaciones en las cuales puede usarlo. Para adquirir esta habilidad, en primer lugar, deben apropiarse de los conceptos matemáticos necesarios para abordar la construcción del modelo. Al mismo tiempo, estos conceptos les proveerán las bases para la modelación e investigación de otros fenómenos de la vida real. De esta manera, el proceso de aprendizaje tiene un carácter iterativo y complementario a la vez. Ahora bien, ¿cómo crear situaciones de enseñanza en las que se les permita a los estudiantes construir, analizar y criticar modelos matemáticos por sí mismos con el docente actuando como guía? Es posible incluir en un currículum de matemática diversas situaciones que vinculen las matemáticas a la realidad a través de la modelación y las mismas pueden ser organizadas como experiencias de aprendizaje en muy diversas formas. Una de estas formas, no necesariamente la única, es el trabajo en proyectos que incluye que cada estudiante lleve a cabo una tarea de reflexión o de investigación matemática y comunique los resultados o conclusiones obtenidos a través de reportes escritos y/o exposición oral. Por lo general, los estudiantes deben definir las variables importantes, simplificar situaciones complejas, formular e interpretar modelos matemáticos, utilizar recursos disponibles, incluir soporte informático, buscar, sintetizar y analizar información, organizar y comunicar ideas matemáticas y resultados, haciendo una evaluación crítica de los mismos. En este trabajo se presenta una propuesta de proyecto a desarrollar por estudiantes del profesorado en matemática que cursan el tercer año de su carrera. Con la propuesta se intenta ilustrar lo dicho anteriormente. Tres cuestiones fueron consideradas esenciales en la elección del Proyecto: 1) debía ser un problema extraído de la vida real y que fuera capaz de despertar el interés de los estudiantes, 2) las matemáticas emergentes debían ser conocidas o bien factibles de ser aprendidas si era necesario, 3) debía involucrar una variedad de acciones: formulación de modelos, discusiones, resoluciones, visitas, uso de computadora, investigación, lectura, reportes. Y como se pretendía imprimir cierto dinamismo, también el tipo de trabajo debía ser variado: individual, grupal, en clase, extra clase.