Direct methane conversion to methanol by ionic liquid-dissolved platinum catalysts

Ternary systems of inorganic Pt salts and oxides, ionic liquids and concentrated sulfuric acid are effective at catalyzing the direct, selective oxidation of methane to methanol and appear to be more water tolerant than the Catalytica reaction

Three-dimensional tissue scaffolds from interbonded poly(e-caprolactone) fibrous matrices with controlled porosity

In this article, we report on the preparation and cell culture performance of a novel fibrous matrix that has an interbonded fiber architecture, excellent pore interconnectivity, and controlled pore size and porosity. The fibrous matrices were prepared by combining melt-bonding of short synthetic fibers with a template leaching technique. The microcomputed tomography and scanning electron microscopy imaging verified that the fibers in the matrix were highly bonded, forming unique isotropic pore architectures. The average pore size and porosity of the fibrous matrices were controlled by the fiber/template ratio. The matrices having the average pore size of 120, 207, 813, and 994 mm, with the respective porosity of 73%, 88%, 96%, and 97%, were investigated. The applicability of the matrix as a three-dimensional (3D) tissue scaffold for cell culture was demonstrated with two cell lines, rat skin fibroblast and Chinese hamster ovary, and the influences of the matrix porosity and surface area on the cell culture performance were examined. Both cell lines grew successfully in the matrices, but they showed different preferences in pore size and porosity. Compared with two-dimensional tissue culture plates, the cell number on 3D fibrous matrices was increased by 97.27% for the Chinese hamster ovary cells and 49.46% for the fibroblasts after 21 days of culture. The fibroblasts in the matrices not only grew along the fiber surface but also bridged among the fibers, which was much different from those on two-dimensional scaffolds. Such an interbonded fibrous matrix may be useful for developing new fiber-based 3D tissue scaffolds for various cell culture applications

Developing a Drought Planning Evaluation System in the United States

Drought is a normal part of the climate cycle, affecting every climate regime on the planet. Drought indicates a special period in which an unusual moisture scarcity causes a serious hydrological imbalance. Drought is related to the timing and effectiveness of the rains, high temperature, high wind, and low humidity. The typical impacts of drought may include dry lands, low or empty water-supply reservoirs, low groundwater levels (dried up wells), crop damage, and ensuing environmental degradation. In the United States, drought accounts for losses in the billions of dollars. In fact, a FEMA (1995) report estimates the average annual losses due to drought at $6-8 billion, on a par with hurricanes, making these the two most costly hazards impacting our country. Drought often affects several sectors (agriculture, recreation and tourism, energy, forestry, and others) at the same time and typically impacts large areas and many people. These impacts serve as indicators of our vulnerability and risk during extended periods of rainfall deficits. Our vulnerability to drought is affected by (among other factors) population growth and shifts, urbanization and sprawl, demographic characteristics, technology, water use trends, government policy, social behavior, and environmental awareness. These factors are continually changing, and society\u27s vulnerability to drought can increase or decrease in response to these changes. Although drought is a natural hazard, society can reduce its vulnerability and therefore lessen the risks associated with drought episodes. The impacts of drought, like those of other natural hazards, can be reduced through mitigation and preparedness. Planning ahead in an attempt to mitigate drought gives decision makers the chance to relieve the most suffering at the least expense. Reacting to drought in crisis mode decreases self-reliance and increases dependence on government and donors (Wilhite and Pulwarty, 2005). As a proof of concept approach, this paper looks into the process of comparing and evaluating state drought plans within the United States. The idea of evaluating (scoring) drought plans may be new, but similar methods have been applied to other hazards and in other planning fields, such as the environmental and urban/rural planning sectors (Baer 1997; Berke 2000; Brody 2003; Tang et a\. 2008). Even so, the planning profession itself has developed relatively few criteria for evaluating the quality of plans, so plan quality is difficult to define (Baer 1997). Now, and in a changing climate with changing vulnerabilities, Brody (2003) aptly notes that planners must be flexible, adapting and planning for changing conditions by gearing their efforts more toward uncertainty and surprise. Thus, the purpose of this paper is to assess the potential transferability of evaluation techniques in other fields and hazards to the evaluation of drought plans in the United States

Developing a Drought Planning Evaluation System in the United States

Drought is a normal part of the climate cycle, affecting every climate regime on the planet. Drought indicates a special period in which an unusual moisture scarcity causes a serious hydrological imbalance. Drought is related to the timing and effectiveness of the rains, high temperature, high wind, and low humidity. The typical impacts of drought may include dry lands, low or empty water-supply reservoirs, low groundwater levels (dried up wells), crop damage, and ensuing environmental degradation. In the United States, drought accounts for losses in the billions of dollars. In fact, a FEMA (1995) report estimates the average annual losses due to drought at $6-8 billion, on a par with hurricanes, making these the two most costly hazards impacting our country. Drought often affects several sectors (agriculture, recreation and tourism, energy, forestry, and others) at the same time and typically impacts large areas and many people. These impacts serve as indicators of our vulnerability and risk during extended periods of rainfall deficits. Our vulnerability to drought is affected by (among other factors) population growth and shifts, urbanization and sprawl, demographic characteristics, technology, water use trends, government policy, social behavior, and environmental awareness. These factors are continually changing, and society\u27s vulnerability to drought can increase or decrease in response to these changes. Although drought is a natural hazard, society can reduce its vulnerability and therefore lessen the risks associated with drought episodes. The impacts of drought, like those of other natural hazards, can be reduced through mitigation and preparedness. Planning ahead in an attempt to mitigate drought gives decision makers the chance to relieve the most suffering at the least expense. Reacting to drought in crisis mode decreases self-reliance and increases dependence on government and donors (Wilhite and Pulwarty, 2005). As a proof of concept approach, this paper looks into the process of comparing and evaluating state drought plans within the United States. The idea of evaluating (scoring) drought plans may be new, but similar methods have been applied to other hazards and in other planning fields, such as the environmental and urban/rural planning sectors (Baer 1997; Berke 2000; Brody 2003; Tang et a\. 2008). Even so, the planning profession itself has developed relatively few criteria for evaluating the quality of plans, so plan quality is difficult to define (Baer 1997). Now, and in a changing climate with changing vulnerabilities, Brody (2003) aptly notes that planners must be flexible, adapting and planning for changing conditions by gearing their efforts more toward uncertainty and surprise. Thus, the purpose of this paper is to assess the potential transferability of evaluation techniques in other fields and hazards to the evaluation of drought plans in the United States

Social networks: evolving graphs with memory dependent edges

The plethora, and mass take up, of digital communication tech- nologies has resulted in a wealth of interest in social network data collection and analysis in recent years. Within many such networks the interactions are transient: thus those networks evolve over time. In this paper we introduce a class of models for such networks using evolving graphs with memory dependent edges, which may appear and disappear according to their recent history. We consider time discrete and time continuous variants of the model. We consider the long term asymptotic behaviour as a function of parameters controlling the memory dependence. In particular we show that such networks may continue evolving forever, or else may quench and become static (containing immortal and/or extinct edges). This depends on the ex- istence or otherwise of certain infinite products and series involving age dependent model parameters. To test these ideas we show how model parameters may be calibrated based on limited samples of time dependent data, and we apply these concepts to three real networks: summary data on mobile phone use from a developing region; online social-business network data from China; and disaggregated mobile phone communications data from a reality mining experiment in the US. In each case we show that there is evidence for memory dependent dynamics, such as that embodied within the class of models proposed here

When is Better Best? A multiobjective perspective

Purpose: To identify the most informative methods for reporting results of treatment planning comparisons. Methods: Seven papers from the past year of International Journal of Radiation Oncology Biology Physics reported on comparisons of treatment plans for IMRT and IMAT. The papers were reviewed to identify methods of comparisons. Decision theoretical concepts were used to evaluate the study methods and highlight those that provide the most information. Results: None of the studies examined the correlation between objectives. Statistical comparisons provided some information but not enough to make provide support for a robust decision analysis. Conclusion: The increased use of treatment planning studies to evaluate different methods in radiation therapy requires improved standards for designing the studies and reporting the results

Communicability across evolving networks

Many natural and technological applications generate time ordered sequences of networks, defined over a fixed set of nodes; for example time-stamped information about ‘who phoned who’ or ‘who came into contact with who’ arise naturally in studies of communication and the spread of disease. Concepts and algorithms for static networks do not immediately carry through to this dynamic setting. For example, suppose A and B interact in the morning, and then B and C interact in the afternoon. Information, or disease, may then pass from A to C, but not vice versa. This subtlety is lost if we simply summarize using the daily aggregate network given by the chain A-B-C. However, using a natural definition of a walk on an evolving network, we show that classic centrality measures from the static setting can be extended in a computationally convenient manner. In particular, communicability indices can be computed to summarize the ability of each node to broadcast and receive information. The computations involve basic operations in linear algebra, and the asymmetry caused by time’s arrow is captured naturally through the non-mutativity of matrix-matrix multiplication. Illustrative examples are given for both synthetic and real-world communication data sets. We also discuss the use of the new centrality measures for real-time monitoring and prediction