Evaluation of biogeochemical model simulations using World Ocean Atlas and satellite observations in the Arabian Sea

Model simulations of the Ocean General Circulation Model (OGCM; MOM4p1), coupled with a state-of-the-art biogeochemical model TOPAZ (Tracers of Phytoplankton with Allometric Zooplankton), which includes multi-nutrient limitations including iron limitation, are used to study the seasonal variations of mixed-layer properties and their influence on nutrients and chlorophyll in the Arabian Sea. The spatial variation of nitrate during the Northeast Monsoon (NEM) and Southwest Monsoon (SWM), in the northern and western parts of the Arabian Sea and coast of Somalia, are very well captured by the model and compare well with observations. Modelled chlorophyll and primary productivity are validated with satellite-derived maps for the Arabian Sea.     

Iron, folate, and vitamin B12 stores among pregnant women in a rural area of Haryana State, India

BACKGROUND: Iron, folate, and vitamin B12 deficiencies have adverse effects on pregnancy outcome. In India, data on the concomitant prevalence of these deficiencies among pregnant women are meager. OBJECTIVE: We conducted a community-based study to assess the prevalence of deficiencies of iron, folate, and vitamin B12 among pregnant women in a rural block of Haryana State. METHODS: The study was approved by the ethics committee of the All India Institute of Medical Sciences, New Delhi. A total of 283 pregnant women were enrolled in the study. After oral informed consent had been obtained from the women, blood was drawn from the antecubital vein for estimation of the levels of serum ferritin by enzyme-linked immunosorbent assay (levels < 12 ng/ mL were considered as indicative of poor iron stores); serum folate was determined by radioimmunoassay (levels <3 ng/mL were considered as indicative of poor folate stores); and serum vitamin B12 was estimated by the microbiologic method (levels < 200 pg/mL were considered as indicative of poor vitamin B12 stores). RESULTS: The results indicated that 67.7%, 26.3%, and 74.1% of the women had poor iron, folate, and vitamin B12 stores, respectively. Concomitant deficiencies of iron, folate, and vitamin B12 occurred in 16.2% of the women. We found that 59.9% of the women were consuming less than 75% of the recommended daily caloric allowance (2175 kcal), indicating an overall poor food intake. This could be one of the predominant reasons for poor iron, folate, and vitamin B12 stores among the women. CONCLUSIONS: Our findings suggest that apart from iron and folate, vitamin B12 deficiencies may play an important role in causing anemia.     

Graceful degradation in algorithm-based fault tolerantmultiprocessor systems

Algorithm-based fault tolerance (ABFT) is a technique which improves the reliability of a multiprocessor system by providing concurrent error detection and fault location capability to it. It encodes data at the system level and modifies the algorithm to operate on the encoded data in order to expose both transient and permanent faults in any processor. Work done till now in this area takes care of only the fault detection and location part of the problem. However, if spare processors are not available, then after a faulty processor has been located, the work initially assigned to it has to be mapped to some nonfaulty processors in the system in such a way that the fault tolerance capability of the system is still maintained with as small a degradation in performance as possible. In this paper, we propose an integrated deterministic solution to the above problem which combines concurrent error detection and fault location with graceful degradation. There exists no previous deterministic ABFT method for the design of general t-fault locating systems, even for the case of t=1. We propose a general method for designing one-fault locating/s-fault detecting systems. We use an extended model for representing ABFT systems. This model considers the processors computing the checks to be a part of the ABFT system, so that faults in the check computing processors can also be detected and located using a simple diagnosis algorithm, and the checks can be mapped to other nonfaulty processors in the system     

IEEE 802.21: Media independent handover: Features, applicability, and realization

Providing users of multi-interface devices the ability to roam between different access networks is becoming a key requirement for service providers. The availability of multiple mobile broadband access technologies, together with the increasing use of real-time multimedia applications, is creating strong demand for handover solutions that can seamlessly and securely transition user sessions across different access technologies. A key challenge to meeting this growing demand is to ensure handover performance, measured in terms of latency and loss. In addition, handover solutions must allow service providers, application providers, and other entities to implement handover policies based on a variety of operational and business requirements. Therefore, standards are required that can facilitate seamless handover between such heterogeneous access networks and that can work with multiple mobility management mechanisms. The IEEE 802.21 standard addresses this problem space by providing a media-independent framework and associated services to enable seamless handover between heterogeneous access technologies. In this article, we discuss how the IEEE 802.21 standard framework and services are addressing the challenges of seamless mobility for multi-interface devices. In addition, we describe and discuss design considerations for a proof-of-concept IEEE 802.21 implementation and share practical insights into how this standard can optimize handover performance.     

Effect of nonlinear mortality and self-grazing on the dynamics of a marine ecosystem

Do the nonlinear terms arising from mortality or self-grazing of zooplankton have significant effect in suppressing limit cycles or autooscillations of marine ecosystem models that are observed under certain conditions? This question is examined with the help of the phase-plane analysis of a class of basic marine ecosystem models. It is found that even a rather small nonlinear term describing nonlinearity in mortality or self-grazing can effectively alter the linear stability conditions and thereby suppress the limit cycles.     

Analysis and randomized design of algorithm-based fault tolerantmultiprocessor systems under an extended model

Reliability of compute-intensive applications can be improved by introducing fault tolerance into the system. Algorithm based fault tolerance (ABFT) is a low-cost scheme which provides the required fault tolerance to the system through system level encoding. In this paper, we propose randomized construction techniques, under an extended model, for the design of ABFT systems with the required fault tolerance capability. The model considers failures in the processors performing the checking operations