1,676 research outputs found
Fuels for Future Electric Power
OVER THE NEXT FORTY YEARS, THE U.S. WILL EXPERIENCE PROBLEMS BECAUSE OF DWINDLING SUPPLIES OF FOSSIL FUELS AND AN INCREASING DEPENDENCE ON FOREIGN OIL. SEVERAL ALTERNATIVES ARE AVAILABLE, SUCH AS MORE STRINGENT CONSERVATION MEASURES OR ALTERNATIVE SOURCES OF ENERGY. HOWEVER, NO SINGLE ALTERNATIVE WILL BE SUFFICIENT. A STUDY WAS CONDUCTED TO DETERMINE THE MOST EFFICIENT ALLOCATION POSSIBLE OF RESOURCES. THE ANALYSIS WAS CONDUCTED ON THE BASIS OF ASSUMED HAPPENINGS IN THE FUTURE RATHER THAN BY PROJECTING HISTORIC TRENDS INTO THE FUTURE. FOR EXAMPLE, AS ONE SOURCE OF ENERGY SUCH AS OIL BECOMES MORE SCARCE, THE COST WILL GO UP, INDUCING A CHANGE TO ANOTHER SOURCE. SYNTHETIC FUELS FROM COAL AND HYDROGEN FROM ELECTROLYSIS WILL BECOME MORE PRACTICAL BY THE END OF THE CENTURY. COAL AND OIL WILL BE USED. HEAVILY THIS CENTURY WITH NUCLEAR FUEL BECOMING MORE EFFICIENT EARLY IN THE NEXT CENTURY. CHART
Self-stabilizing algorithms for Connected Vertex Cover and Clique decomposition problems
In many wireless networks, there is no fixed physical backbone nor
centralized network management. The nodes of such a network have to
self-organize in order to maintain a virtual backbone used to route messages.
Moreover, any node of the network can be a priori at the origin of a malicious
attack. Thus, in one hand the backbone must be fault-tolerant and in other hand
it can be useful to monitor all network communications to identify an attack as
soon as possible. We are interested in the minimum \emph{Connected Vertex
Cover} problem, a generalization of the classical minimum Vertex Cover problem,
which allows to obtain a connected backbone. Recently, Delbot et
al.~\cite{DelbotLP13} proposed a new centralized algorithm with a constant
approximation ratio of for this problem. In this paper, we propose a
distributed and self-stabilizing version of their algorithm with the same
approximation guarantee. To the best knowledge of the authors, it is the first
distributed and fault-tolerant algorithm for this problem. The approach
followed to solve the considered problem is based on the construction of a
connected minimal clique partition. Therefore, we also design the first
distributed self-stabilizing algorithm for this problem, which is of
independent interest
Parental stress before, during, and after pediatric stem cell transplantation: a review article
Goals of work: Pediatric stem cell transplantation (SCT) is a stressful treatment for children with relapsed or high-risk malignancies, immune deficiencies and certain blood diseases. Parents of children undergoing SCT can experience ongoing stress related to the SCT period. The aim of this article was to present a literature review of articles on parental distress and adaptation before, during, and after SCT and to identify risk and protective factors. Materials and methods: The review was conducted systematically by using PubMed, Web of Science, PsychInfo, and Picarta databases. Eighteen articles met our inclusion criteria: publishing date between January 1, 1990 and January 1, 2009; studies concerning parents of children undergoing SCT; studies examining the psychological adjustment and/or stress reactions of parents as primary outcomes and studies available in English. Main results: Highest levels of parental stress are reported in the period preceding SCT and during the acute phase. Stress levels decrease steadily after discharge in most parents. However, in a subgroup of parents, stress levels still remain elevated post-SCT. Parents most at risk in the longer term display highest levels of stress during the acute phase of the SCT. Conclusions: Psychosocial assessment before SCT, during the acute phase and in the longer term, is necessary to identify parents in need for support and follow-up care
Effects of Transport Memory and Nonlinear Damping in a Generalized Fisher's Equation
Memory effects in transport require, for their incorporation into reaction
diffusion investigations, a generalization of traditional equations. The
well-known Fisher's equation, which combines diffusion with a logistic
nonlinearity, is generalized to include memory effects and traveling wave
solutions of the equation are found. Comparison is made with alternate
generalization procedures.Comment: 6 pages, 4 figures, RevTeX
Homoleptic [ONO]2Ti(IV) type complexes of amino-acid-tethered phenolato, Schiff-base ligands: Synthesis, characterization, time-resolved fluorescence spectroscopy, and cytotoxicity against ovarian and colon cancer cells
Six homoleptic Ti(IV) compounds of dianionic tridentate Schiff base ligands were synthesized from chiral amino acids, 2-hydroxybenzaldehyde and Ti(OiPr)4. The
compounds were spectroscopically characterized and the molecular geometries were established by X-ray crystallography. The ligands coordinated the titanium via
carboxylate-O-, imine-N-, and phenoxide-O atoms. Two isomers were identified; each based on a trans-N2O4 donor set, but one with trans carboxylate-O atoms and another with each carboxylate-O atom trans to a phenoxide-O atom. Photophysical profiles exhibited faster excited-state relaxation in the solid phase than in solution.
Marked cytotoxicities were recorded toward human ovarian A2780 and colon HT-29 cancer cells with IC50 values ranging between 23±2 and 103±3 ”M. Comparative hydrolytic stability studies by NMR in 10% D2O solutions provided t1/2 values of up to 15±2 h, with little correlation to cytotoxicity implying a role of hydrolysis products in the reactivity and identifying steric bulk as a contributor to stability and solubility
Class of self-limiting growth models in the presence of nonlinear diffusion
The source term in a reaction-diffusion system, in general, does not involve
explicit time dependence. A class of self-limiting growth models dealing with
animal and tumor growth and bacterial population in a culture, on the other
hand are described by kinetics with explicit functions of time. We analyze a
reaction-diffusion system to study the propagation of spatial front for these
models.Comment: RevTex, 13 pages, 5 figures. To appear in Physical Review
Integrated Economic and Climate Modeling
This survey examines the history and current practice in integrated assessment models (IAMs) of the economics of climate change. It begins with a review of the emerging problem of climate change. The next section provides a brief sketch of the rise of IAMs in the 1970s and beyond. The subsequent section is an extended exposition of one IAM, the DICE/RICE family of models. The purpose of this description is to provide readers an example of how such a model is developed and what the major components are. The ïŹnal section discusses major important open questions that continue to occupy IAM modelers. These involve issues such as the discount rate, uncertainty, the social cost of carbon, the potential for catastrophic climate change, algorithms, and fat-tailed distributions. These issues are ones that pose both deep intellectual challenges as well as important policy implications for climate change and climate-change policy
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