Optical/UV afterglows: Swift UVOT overview

The ultraviolet and optical telescope (UVOT) on Swift provides coverage of gamma-ray bursts and their afterglows in the 170-650 nm band, yielding multiwavelength data of considerable diagnostic power in conjunction with the Swift X-ray Telescope. The results from the first eighteen months of operation show a broad range of afterglow behaviour, with considerably more complexity in many bursts than would be expected from the simple fireball model for the explosion. We briefly illustrate the capabilities of UVOT for measuring the evolution of nearby supernovae by reference to the observations of GRB 060218, and discuss the peculiar case of GRB 060614, which apparently resides in a nearby galaxy but which did not show the expected supernova feature in its light curve due to radioactive nickel decay. We discuss how the combination of X-ray and UV/optical spectral data can be used to investigate the environment of GRB host galaxies.     

Simple, continuous-flow systems for dissolving the water-soluble components of crude oil into sea-water for acute or chronic exposure of marine organisms

A continuous flow apparatus, referred to as a solubilizer, was constructed to dissolve the water-soluble fraction (WSF) of crude oil into water for short and long-term experiments with marine organisms. The basic solubilizer system consists of an oil reservoir, oil pump, modified glass bottle, and oil waste reservoir. This system dissolves the water-soluble components of crude oil without the loss of the more volatile compounds and without the formation of emulsions or oil droplets. Four solubilizer systems (two continuous flow and two recirculating) were evaluated for their efficiency in extracting the water-soluble components from Cook Inlet crude oil by analyzing for six monoaromatics over a 96-h period of continuous operation. When a solubilizer system was started, a stable concentration of the monocyclic aromatics in the water-soluble fraction was reached within 24 h. The water quality of the WSF effluent was not altered markedly in the continuous (open) flow systems, but there was a substantial reduction in dissolved oxygen in the recirculated (closed) systems. A single solubilizer system (open flow) with a 3 ml min⁻¹ oil flow and a 1 l min⁻¹ sea-water flow generated approx. 1.4 ppm of the total monoaromatics, which includes benzene, toluene, ethylbenzene and the three xylene isomers. This concentration varied depending on physical parameters and the chemical composition of the crude oil and water. With only slight modifications of the basic continuous flow system, a higher concentration (> 3.4 ppm total monoaromatics) of the water-soluble fraction of crude oil was achieved. By recirculating the water supply, concentrations of 6.7–11 ppm total monoaromatics in the WSF were produced. The stability, reproducibility, and reliability of the four systems were demonstrated in several experiments. Researchers working in aquatic systems with crude oil can well appreciate a simple system that is easily cleaned, relatively maintenance-free, and which produces stable, reproducible concentrations of the WSF over extended periods of time. The increasing demands for ecological studies on aquatic organisms with crude oil, a difficult mixture of chemicals with which to work, precipitated the development of these solubilizer systems.     

Condensed tannins: A factor limiting the use of cassava forage

Cassava (Manihot esculenta, Crantz), an important tropical root crop, is considered to have a good potential for use as a forage because leaf blades generally contain <20% crude protein (CP). However, neutral-detergent fibre (NDF) obtained from cassava leaf blades contains condensed tannins (CTs) and high levels of CP. The amount of CP in the NDF that is insoluble when treated with pepsin or protease is highly correlated with the amount of CTs in the NDF. CTs in the NDF are rich in prodelphinidin. CTs may be an important factor limiting the nutritive value of cassava forage.     

Viewpoints: principles, problems and a practical approach to requirements engineering

The paper includes a survey and discussion of viewpoint‐oriented approaches to requirements engineering and a presentation of new work in this area which has been designed with practical application in mind. We describe the benefits of viewpoint‐oriented requirements engineering and describe the strengths and weaknesses of a number of viewpoint‐oriented methods. We discuss the practical problems of introducing viewpoint‐oriented requirements engineering into industrial software engineering practice and why these have prevented the widespread use of existing approaches. We then introduce a new model of viewpoints called Preview. Preview viewpoints are flexible, generic entities which can be used in different ways and in different application domains. We describe the novel characteristics of the Preview viewpoints model and the associated processes of requirements discovery, analysis and negotiation. Finally, we discuss how well this approach addresses some outstanding problems in requirements engineering (RE) and the practical industrial problems of introducing new requirements engineering methods.     

Relevance-based abstraction identification: technique and evaluation

When first approaching an unfamiliar domain or requirements document, it is often useful to get a quick grasp of what the essential concepts and entities in the domain are. This process is called abstraction identification, where the word abstraction refers to an entity or concept that has a particular significance in the domain. Abstraction identification has been proposed and evaluated as a useful technique in requirements engineering (RE). In this paper, we propose a new technique for automated abstraction identification called relevance-based abstraction identification (RAI), and evaluate its performance—in multiple configurations and through two refinements—compared to other tools and techniques proposed in the literature, where we find that RAI significantly outperforms previous techniques. We present an experiment measuring the effectiveness of RAI compared to human judgement, and discuss how RAI could be used to good effect in requirements engineering.     

“USB电池充电规范”推动“共享电源”演进

现在的便携式消费电子产品开始采用容量较大的电池,以满足更大屏幕以及更多无线功能(如WiFi、3G、和LTE)所带来的额外的功率需求。目前采用USB接口进行充电已非常普遍,而要进一步提升USB接口的充电效率,以实现更快速的充电,必须有一个能增加PC或集线     

Numerical approaches for collaborative data processing

We present an approach to uncertainty propagation in dynamic systems, exploiting information provided by related experimental results along with their models. The approach relies on a solution mapping technique to approximate mathematical models by polynomial surrogate models. We use these surrogate models to formulate prediction bounds in terms of polynomial optimizations. Recent results on polynomial optimizations are then applied to solve the prediction problem. Two examples which illustrate the key aspects of the proposed algorithm are given. The proposed algorithm offers a framework for collaborative data processing among researchers. This work was supported by the National Science Foundation, Information Technology Research Program, Grant No. CTS-0113985.