Video Experimental Relacionado
Updated: May 12, 2026
22:38
Chemotactic Response of Marine Micro-Organisms to Micro-Scale Nutrient Layers
Published on: May 28, 2007
Un mecanismo de viscosidad mejorada para la mezcla biogénica de océanos
1Bioengineering, California Institute of Technology, Pasadena, California 91125, USA. kakani@caltech.edu
Nature
|July 31, 2009
Resumen
La natación de los animales tiene un impacto significativo en la mezcla de los océanos a través de un mecanismo de mezcla de fluidos darwiniano, no solo la turbulencia. Este proceso, dependiente de la forma del animal, es crucial para el transporte de nutrientes a través de diversas especies acuáticas.
Área de la Ciencia:
- Oceanografía La oceanografía es la oceanografía.
- Biogeoquímica La biogeoquímica es la bioquímica.
- Dinámica de fluidos La dinámica de fluidos.
Sus antecedentes:
- Existen conclusiones contradictorias sobre el papel de la natación animal en la mezcla de los océanos.
- La disipación turbulenta elevada cerca del plancton no es prueba suficiente de la mezcla biogénica.
- La turbulencia de los pequeños animales se disipa como calor antes de afectar a la mezcla de los océanos.
Objetivo del estudio:
- Para identificar el mecanismo dominante de mezcla de fluidos por los animales nadadores.
- Para investigar un mecanismo de mezcla previamente descuidado descrito por Darwin.
- Cuantificar la contribución de la mezcla animal a los procesos oceánicos.
Principales métodos:
- Desarrolló un modelo teórico comparando la mezcla de despertar darwiniano y turbulento.
- Valida el modelo utilizando mediciones de campo in situ de medusas.
- Empleó un nuevo dispositivo de velocimetría láser basado en buceo para las mediciones.
Principales resultados:
- El mecanismo de Darwin, dependiente de la forma del animal, es el proceso de mezcla dominante.
- Este mecanismo se ve reforzado por la viscosidad del fluido y es efectivo para todos los tamaños de animales.
- La mezcla biogénica a través del mecanismo de Darwin contribuye significativamente a la mezcla de los océanos y al transporte de nutrientes.
Conclusiones:
- La forma animal, no sólo la turbulencia, impulsa una importante mezcla oceánica.
- La mezcla darwiniana ofrece una vía de mezcla biogénica consistente entre el zooplancton y los mamíferos marinos.
- Este mecanismo tiene importantes implicaciones para la comprensión de la mezcla de los océanos y el ciclo de nutrientes.
Videos de Conceptos Relacionados
01:17Viscosity
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
01:28The Thermodynamics of Mixing
Mixing is a fascinating phenomenon in thermodynamics, particularly when considering the Gibbs energy of a mixture at constant temperature and pressure. This energy, denoted as G, tends to decrease during spontaneous mixing processes, offering insights into the composition changes that occur.Imagine two ideal gases, initially separated in different containers, with amounts nA and nB, respectively, both at a temperature T and pressure p. The chemical potentials of these gases have their 'pure'...
01:27Viscosity
Viscosity is a property of fluids that measures their resistance to flow. It is influenced by factors such as the surface area of contact, the gradient of flow speed, and the fluid's viscosity constant, called the coefficient of viscosity. The coefficient of viscosity, also known as dynamic viscosity, is denoted by the symbol η. It determines the proportionality between the viscous force and the gradient of flow speed.Newton's law of viscosity states that the viscous force on a faster-moving...
01:19Viscosity of Fluid
Viscosity measures the resistance a fluid offers to flow and deformation. It results from internal friction between layers of fluid moving relative to one another. Dynamic viscosity, denoted by the Greek letter mu (μ), quantifies the force needed to move one fluid layer over another. For Newtonian fluids like water and air, the relationship between the shearing stress and the rate of shearing strain is linear, meaning their viscosity remains constant regardless of the applied stress.
01:30Marine Microbial Ecology
Marine microbial ecosystems are shaped by distinct physicochemical limits, including high salinity, low nutrient availability, and fluctuating oxygen levels. These conditions favor smaller microbial cell sizes, which maximize their surface-to-volume ratio for efficient nutrient uptake.Microbial activity and community composition are closely linked to biogeochemical cycles, particularly in dynamic environments like estuaries, where halotolerant microbes thrive in response to variable salinity...
01:18Bioreactor Controls-II
In aerobic fermentations, oxygen is vital for microbial growth and metabolite production. Since air comprises only about 20% oxygen and the gas is poorly soluble in water—just 9 ppm at 20°C—supplying sufficient oxygen becomes a critical challenge, especially in high-demand processes like yeast growth or citric acid production. Even a fully saturated broth may offer only a few seconds of oxygen availability.To address this, sterile or scrubbed air is introduced into the fermentor via a sparger...