Seasonal patterns of thermal stratification and primary production in the northern parts of Lake Tanganyika

Thermal stratification in meromictic Lake Tanganyika weakens during the cool, dry and windy season, allowing intrusions of deeper nutrient-rich waters into the upper mixed layer enhancing primary productivity. The current study examined the seasonal influence of thermal structure on the patterns of primary production in Lake Tanganyika. Two sites (Kigoma Bay and Mahale) were sampled on a monthly basis for 1?year. Water temperature and chlorophyll a fluorescence profiles (0–100?m) were measured using a multisonde. Water samples were taken every 20?m (0–100?m) to measure soluble reactive phosphorus (SRP), chlorophyll a and primary production. Pulse Amplitude Modulated Fluorometry was used for the measurements of primary production. The results show that the dry season coincided with higher wind speeds, elevated SRP and some peaks of chlorophyll a and primary production at both sites. During the wet season, high levels of chlorophyll a and primary production coincided with an increase in the euphotic depth, a deep chlorophyll maximum (DCM) and a contribution from metalimnetic areal production at both sites. Our results suggest that the vertical distribution of primary production in Lake Tanganyika is affected by the lake thermal structure, nutrient availability and the extent of the euphotic zone. In Lake Tanganyika, estimates of areal primary production were significantly affected by DCM and required estimation throughout the entire upper mixed layer and the metalimnion which extended to ~89?m.     

一种基于流的环公平算法

同时实现空间复用和公平分配是弹性分组环(RPR)的重要目标，在很多环境下按流分配是合理的策略。本文提出一种以GPS(Genemlized Processor Sharing)为基础的算法DFAR—BF。各节点根据本地拥塞状态独立计算公平值，通过控制包向上游反馈，上游节点在比较反馈和本地信息后调整各个流的接入量。仿真表明本算法在一个源节点接入多个流时，能够实现按流公平，在非平衡流的情况下．能够充分利用带宽而不产生抖动。