Archive for June 15th, 2012

A benchmarking framework for simulation-based optimization of environmental models






Abstract: Simulation models assist with designing and managing environmental systems. Linking such models with optimization algorithms yields an approach for identifying least-cost solutions while satisfying system constraints. However, selecting the best optimization algorithm for a given problem is non-trivial and the community would benefit from benchmark problems for comparing various alternatives. To this end, we propose a set of six guidelines for developing effective benchmark problems for simulation-based optimization. The proposed guidelines were used to investigate problems involving sorptive landfill liners for containing and treating hazardous waste. Two solution approaches were applied to these types of problems for the first time – a pre-emptive (i.e. terminating simulations early when appropriate) particle swarm optimizer (PSO), and a hybrid discrete variant of the dynamically dimensioned search algorithm (HD-DDS). Model pre-emption yielded computational savings of up to 70% relative to non-pre-emptive counterparts. Furthermore, HD-DDS often identified globally optimal designs while incurring minimal computational expense, relative to alternative algorithms. Results also highlight the usefulness of organizing decision variables in terms of cost values rather than grouping by material type. [Copyright &y& Elsevier]


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‘life-style’ control networks in escherichia coli: signaling by the second messenger c-di-gmp

Abstract: Most bacteria can exist in either a planktonic-motile single-cell state or an adhesive multicellular state known as a biofilm. Biofilms cause medical problems and technical damage since they are resistant against antibiotics, disinfectants or the attacks of the immune system. In recent years it has become clear that most bacteria use cyclic diguanylate (c-di-GMP) as a biofilm-promoting second messenger molecule. C-di-GMP is produced by GGDEF-domain-containing diguanylate cyclases and is degraded by phosphodiesterases featuring EAL or HD-GYP domains. Many bacterial species possess multiple proteins with GGDEF and EAL domains, which actually belong to the most abundant protein families in genomic data bases. Via an unprecedented variety of effector components, which include c-di-GMP-binding proteins as well as RNAs, c-di-GMP controls a wide range of targets that down-regulate motility, stimulate adhesin and biofilm matrix formation or even control virulence gene expression. Moreover, local c-di-GMP signaling in macromolecular complexes seems to allow the independent and parallel control of different output reactions. In this review, we use Escherichia coli as a paradigm for c-di-GMP signaling. Despite the huge diversity of components and molecular processes involved in biofilm formation throughout the bacterial kingdom, c-di-GMP signaling represents a unifying principle, which suggests that the enzymes that make and break c-di-GMP may be promising targets for anti-biofilm drugs. [Copyright &y& Elsevier]

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Work materials catch fire at 1 world trade center site

Firefighters scrambled to contain a small fire that was discovered on Saturday after it had apparently smoldered overnight amid construction debris and plywood on the 89th floor of 1 World Trade Center in Lower Manhattan, the authorities said. One firefighter suffered minor injuries in the fire, which was discovered shortly after 7 a.m., according to James Long, a Fire Department spokesman. The ”main body” of the fire was extinguished by 8:19 a.m., said Assistant Chief James E. Esposito, the department’s top commander in Manahttan.

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Wisdom from little brother

My older sister is 17, and we’ve always had a pretty good relationship. At school, kids have started saying mean things about her because of the way she dresses, like ”What a tramp!” and other things that are not true. The thing is, she is dressing sexier than she used to, and sexier than the other girls, by far. This problem is only going to get worse if she wears the dress she just bought for prom. My parents are totally clueless. Should I talk to them about this?Matt You may be the best younger sibling since Phoebe Caulfield in ”Catcher in the Rye.” (If you haven’t read it, promise me you will.) And your sister is lucky to have you.

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William hanauer, alan stahl

William R Hanauer and Alan Michael Stahl are to be married Sunday in Sparta Park in Ossining, N.Y. The Rev. Lynda Clements, a Presbyterian minister, is to perform the ceremony. Mr. Hanauer (left), 65, is the mayor of the Village of Ossining. He graduated from Queens College. He is a son of the late Ethel R. Hanauer and the late Milton L. Hanauer, who lived and worked in New York. His mother retired as a guidance counselor at Julia Richman High School. His father retired as the principal of Junior High School 52.

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Where the trough is overflowing

Every five years or so, Congress promises a new, improved farm bill that will end unnecessary subsidies to big farmers, enhance the environment and actually do something to help small farmers and small towns. But what it usually does is find ways of disguising the old inequities, sending taxpayers dollars to wealthy farmers, accelerating the expansion of industrial farming, inflating land prices and further depopulating rural America. The new five-year farm bill that could hit the Senate floor as early as this week promises more of the same — excessively generous handouts, combined with a serious erosion of environmental protections. The nearly trillion-dollar bill would provide over 10 years roughly $140 billion in farm subsidies, $55 billion or so in conservation programs and more than $750 billion in food stamp aid.

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What’s at stake in the belmont

The horse racing industry should be deeply shamed that extraordinary security measures had to be ordered to guard horses in next Saturday’s Belmont Stakes from the doping abuses engulfing thoroughbred racing. The horses will be kept in an isolated barn with visitors limited, feed and hay bales checked for drugs, and veterinarians and trainers under daily watch to ensure there is no manipulation of food or medication. If anyone thinks this is an overreaction, they should take a look at the record of Doug O’Neill. He is the trainer of I’ll Have Another, the horse primed for the chance to be a Triple Crown champion after winning the Kentucky Derby and the Preakness Stakes. Mr. O’Neill has a long history of racing sanctions and penalties for administering illegal and dangerous performance-enhancing concoctions. He isn’t an outlier. Of racing’s top 20 trainers, only two have never been cited for abusing medications.

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Weak economy points to obama’s constraints

WASHINGTON — The bleak jobs report on Friday predictably had heads snapping toward the White House, looking to President Obama to do something. Yet his proposed remedies only underscore how much the president, just five months before he faces voters, is at the mercy of actors in Europe, China and Congress whose political interests often conflict with his own. That day, Mr. Obama continued his weekly travels around the country, prodding Congressional Republicans to pass his ”to-do list” of temporary tax cuts and spending initiatives to help create jobs. The Republicans only mock him, which leaves Mr. Obama free to blame his opponents and their presidential standard-bearer, Mitt Romney. But in doing so, he telegraphs a message of powerlessness that no leader likes to convey — least of all one who ran for office four years ago vowing to bridge Washington’s partisan gulf.

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Wave of gun violence challenges seattle’s notion of security

SEATTLE — The worst surge of gun violence in years, culminating last week in six deaths over the course of an otherwise unremarkable Wednesday morning-into-afternoon, has deeply stressed this city, where many neighborhoods normally feel as safe as living rooms. The timing of the crime wave is almost as jarring. It comes in the middle of a complex political dance between the city and the Department of Justice over how the Seattle Police Department should change its practices and policies after a series of high-profile incidents that showed what federal investigators called ”a pattern or practice of excessive force.”

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Warren avoids primary as she seeks to right massachusetts senate bid

SPRINGFIELD, Mass. — In a display of political muscle, Elizabeth Warren overwhelmingly won the state Democratic Party’s endorsement on Saturday for the United States Senate seat held by Scott P. Brown, a Republican. With the size of her victory, she avoided a party primary in September. Ms. Warren, whose campaign had appeared to be flailing over the past month under questions about her American Indian heritage, won 95.7 percent of the vote of the 3,500 delegates attending the state party convention here. Because the only other Democrat running, Marisa DeFranco, failed to capture 15 percent of the vote, Ms. DeFranco lost the chance to mount a primary challenge.

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