Gateway selection in multi-hop wireless networks

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 61-63).This thesis describes the implementation of MultiNAT, an application that attempts to provide the benefits of client multi-homing while requiring minimal client configuration, and the evaluation of a novel link-selection algorithm, called AvMet, that significantly outperforms earlier multi-homing methods. The main motivation behind MultiNAT is the growing popularity of cheap broadband Internet connections, which are still not reliable enough for important applications. The increasing prevalence of wireless networks, with their attendant unpredictability and high rates of loss, is further exacerbating the situation. Recent work has shown that multi-homing can increase both Internet performance as well as the end-to-end availability of Internet services. Most previous solutions have required complicated client configuration or have routed packets through dedicated overlay networks; MultiNAT attempts to provide a simpler solution. MultiNAT automatically forwards connection attempts over all local interfaces and uses the resulting connection establishment times along with link-selection metrics to select which interface to use.(cont.) MultiNAT is able to sustain transfer speeds in excess of 4 megabytes per second, while imposing only an extra 150 microseconds of latency per packet. MultiNAT supports a variety of link-selection metrics, each with its own strengths and weaknesses. The MONET race-based scheme works well in wired networks, but is misled by the unpredictable nature of wireless losses. The ETT metric performs relatively well at finding high-throughput paths in multi-hop wireless networks, but can be incorrect when faced with heavy load. Unfortunately, neither of these metrics address end-to-end performance when packets traverse both wired and wireless networks. To fill this need, we propose AvMet, a link-selection scheme that tracks past connection history in order to improve current predictions. We evaluate AvMet on a variety of network configurations and find that AvMet is not misled by wireless losses. AvMet is able to outperform existing predictors in all network configurations and can imp:rove end-to-end availability by up to half an order of magnitude.by Rohit Navalgund Rao.M.Eng

Near Infrared Spectroscopy Describes Physiologic Payback Associated With Excess Postexercise Oxygen Consumption in Healthy Controls and Children With Complex Congenital Heart Disease

Exercise creates a physiologic burden with recovery from such effort crucial to adaptation. Excess postexercise oxygen consumption (EPOC) refers to the body’s increased metabolic need after work. This investigation was designed to determine the role of near infrared spectroscopy (NIRS) in the description of exercise recovery in healthy controls (NL) and children with congenital heart disease (CHD). Subjects were recruited with exercise testing performed to exhaustion. Exercise time (EXT), heart rate (HR), and oxygen consumption (VO2) were measured. Four-site NIRS (brain, kidney, deltoid, and vastus lateralis) were measured during exercise and into recovery to establish trends. Fifty individuals were recruited for each group (NL = 26 boys and 24 girls; CHD = 33 boys and 17 girls). Significant differences existed between EXT, VO2, and peak HR (P \u3c 0.01). NIRS values were examined at four distinct intervals: rest, peak work, and 2 and 5 min after exercise. Significant cerebral hyperemia was seen in children with CHD post exercise when compared to normal individuals in whom redistribution patterns were directed to somatic muscles. These identified trends support an immediate compensation of organ systems to re-establish homeostasis in peripheral beds through enhanced perfusion. Noninvasive NIRS monitoring helps delineate patterns of redistribution associated with EPOC in healthy adolescents and children with CHD

Near Infrared Spectroscopic Monitoring During Cardiopulmonary Exercise Testing Detects Anaerobic Threshold

Cardiopulmonary exercise testing (CPET) provides assessment of the integrative responses involving the pulmonary, cardiovascular, and skeletal muscle systems. Application of exercise testing remains limited to children who are able to understand and cooperate with the exercise protocol. Near-infrared spectroscopy (NIRS) provides a noninvasive, continuous method to monitor regional tissue oxygenation (rSO2). Our specific aim was to predict anaerobic threshold (AT) during CPET noninvasively using two-site NIRS monitoring. Achievement of a practical noninvasive technology for estimating AT will increase the compatibility of CPET. Patients without structural or acquired heart disease were eligible for inclusion if they were ordered to undergo CPET by a cardiologist. Data from 51 subjects was analyzed. The ventilatory anaerobic threshold (VAT) was computed on VCO2 and respiratory quotient post hoc using the standard V-slope method. The inflection points of the regional rSO2 time-series were identified as the noninvasive regional NIRS AT for each of the two monitored regions (cerebral and kidney). AT calculation made using an average of kidney and brain NIRS matched the calculation made by VAT for the same patient. Two-site NIRS monitoring of visceral organs is a predictor of AT

First record of threadfin bream, Nemipterus zysron (Bleeker, 1857) from Andhra Pradesh Coast

Threadfin breams, a major demersal resource of Visakhapatnam region is represented by a single genus Nemipterus and is fished extensively by trawlers. Five species of this genus viz., Nemipterus mesoprion, N. japonicus, N. delagoae, N. Iuteus and N. tolu generally contribute to the fishery of the region. A sixth species, Nemipterus zysron was collected and identified from the catch at Visakhapatnam Fishing Harbour on 15th July 2008

Small-scale tuna fishery of the Western Bay of Bengal

Fishing for the yellowfin tuna in the western part of the Bay of Bengal by traditional Indian coastal fisherfolk is a recent development. Tuna fishing has reached the status of a major industry with several private fishery stakeholders actively involve

The Landau-Bloch type theorems for certain class of holomorphic and pluriharmonic mappings in cn\mathbb{c}^n

In this paper, we first define two classes of holomorphic mappings defined on the unit ball $B^n$ of n-dimensional complex space $\mathbb{C}^n$ and obtain the lower estimates for Bloch's constant for these classes. Also, we derive the Landau-Bloch type theorem for some subclasses of pluriharmonic mappings defined on the unit ball $B^n$.Comment: 1