Category Archives: Peer Reviewed Article Review

transportation megaprojects exceed cost estimates by 28%

According to this Danish study, worldwide transportation “megaprojects” exceed their projected costs by an average of 28%.

  • In 9 out of 10 transportation infrastructure projects, costs are underestimated.
  • For rail projects, actual costs are on average 45% higher than estimated costs (sd=38).
  • For fixed-link projects (tunnels and bridges), actual costs are on average 34% higher than estimated costs (sd=62).
  • For road projects, actual costs are on average 20% higher than estimated costs (sd=30).
  • For all project types, actual costs are on average 28% higher than estimated costs (sd=39).
  • Cost underestimation exists across 20 nations and 5 continents; it appears to be a global phenomenon.
  • Cost underestimation appears to be more pronounced in developing nations than in North America and Europe (data for rail projects only).
  • Cost underestimation has not decreased over the past 70 years. No learning that would improve cost estimate accuracy seems to take place.
  • Cost underestimation cannot be explained by error and seems to be best explained by strategic misrepresentation, i.e., lying.
  • Transportation infrastructure projects do not appear to be more prone to cost underestimation than are other types of large projects.

biodiversity and ecosystem services in decisions

Here’s an “open-source software tool for integrating biodiversity and ecosystem services into impact assessment and mitigation decisions“.

Governments and financial institutions increasingly require that environmental impact assessment and mitigation account for consequences to both biodiversity and ecosystem services. Here we present a new software tool, OPAL (Offset Portfolio Analyzer and Locator), which maps and quantifies the impacts of development on habitat and ecosystem services, and facilitates the selection of mitigation activities to offset losses. We demonstrate its application with an oil and gas extraction facility in Colombia. OPAL is the first tool to provide direct consideration of the distribution of ecosystem service benefits among people in a mitigation context. Previous biodiversity-focused efforts led to redistribution or loss of ecosystem services with environmental justice implications. Joint consideration of biodiversity and ecosystem services enables targeting of offsets to benefit both nature and society. OPAL reduces the time and technical expertise required for these analyses and has the flexibility to be used across a range of geographic and policy contexts.

everyday chemicals and the developing brain

This is a disturbing article about the effects of common chemicals on childrens’ developing brains. I don’t get too alarmed when I hear this stuff from hte anti-vaccine and anti-GMO crowd, but this article is signed by dozens of scientists who study the brain.

Children in America today are at an unacceptably high risk of developing neurodevelopmental disorders that affect the brain and nervous system including autism, attention deficit hyperactivity disorder, intellectual disabilities, and other learning and behavioral disabilities. These are complex disorders with multiple causes—genetic, social, and environmental. The contribution of toxic chemicals to these disorders can be prevented…These include chemicals that are used extensively in consumer products and that have become widespread in the environment. Some are chemicals to which children and pregnant women are regularly exposed, and they are detected in the bodies of virtually all Americans in national surveys conducted by the U.S. Centers for Disease Control and Prevention. The vast majority of chemicals in industrial and consumer products undergo almost no testing for developmental neurotoxicity or other health effects.

To me, there is a difference between chemicals used in industry and agriculture, and chemicals found in everyday household products. We should be looking for truly safe and nontoxic substitutes for all of them, but the latter are particularly important both because the public is exposed to them directly, and because in some cases they are just not necessary. When I read the label on a bottle of shampoo I can’t help wondering if the chemical soup that is in there is really necessary to cleanse my hair, and even if were, cleansing my hair is not a matter of life and death.

gene circuits

Here’s another article on the idea of designed biological circuits.

Synthetic mixed-signal computation in living cells

Living cells implement complex computations on the continuous environmental signals that they encounter. These computations involve both analogue- and digital-like processing of signals to give rise to complex developmental programs, context-dependent behaviours and homeostatic activities. In contrast to natural biological systems, synthetic biological systems have largely focused on either digital or analogue computation separately. Here we integrate analogue and digital computation to implement complex hybrid synthetic genetic programs in living cells. We present a framework for building comparator gene circuits to digitize analogue inputs based on different thresholds. We then demonstrate that comparators can be predictably composed together to build band-pass filters, ternary logic systems and multi-level analogue-to-digital converters. In addition, we interface these analogue-to-digital circuits with other digital gene circuits to enable concentration-dependent logic. We expect that this hybrid computational paradigm will enable new industrial, diagnostic and therapeutic applications with engineered cells.

more on the new cancer treatments

The BBC has a bit more on the leading edge in cancer research and treatment:

Cancer is entering a “new era” of personalised medicine with drugs targeted to the specific weaknesses in each patient’s tumour, say doctors…

The idea of precision medicine is to test every patient’s tumour, find the mutations that have become essential for it to survive and then select a targeted drug to counter-act the mutation – killing the tumour…

a revolution in genetics – allowing scientists to rapidly and cheaply interrogate a cancer’s corrupted DNA – is leading to huge excitement about a new generation of precision drugs.

urban vegetation design for heat

When you see completely mangled English in a paper that has supposedly passed peer review, you have to wonder about the quality of the peer review. Nonetheless, I was interested in the results of this study that looked at trees, shrubs, and lawn to see which had the most effect on urban heat.

Numerical simulation of the impact of different vegetation species on the outdoor thermal environment

For air temperature at 1.5 m and thermal comfort and safety (PET and WBGT), the sequence is trees> lawn> shrubs, but for surface temperature, the sequence is lawn> shrubs> trees

I’m always interested in the idea of designing urban areas to maximize hydrologic function, ecological function, and human comfort simultaneously. There is so much that could be done, and so much closed-mindedness and poor communication among the various professions and disciplines that could be doing it.

I’ve always assumed trees are the gold standard, because you get both the evapotranspiration function and the shading function, whereas with lawn and shrubs you only get the former. Also, you only need a small area of soil to plant the tree (although often more than we allow in urban areas), and then its leaves can cover a large area of concrete or asphalt, which would otherwise be generating a lot of heat and polluted runoff. Also, grass provides very little ecological function (unless you let it grow taller and/or take a lenient approach to what some of your neighbors choose to define as “weeds”, which can be socially unacceptable), where trees and bushes provide ecological function. Bushes take up a lot of space, either in a sidewalk context or a small urban yard – paradoxically, once trees mature a little bit they take up less space because there is space under them. On the other hand, I’ve argued with purists that if people really want lawn in urban areas, it is a lot better than concrete in terms of hydrology, heat, and aesthetics. Although if you’re in a water-stressed area, that adds another factor to the hydrology equation that those of us in wetter areas have the luxury of not worrying about too much.

no coffee grounds in compost?

This article is a bit disturbing, because I have been composting coffee grounds for years with seemingly good results. Then again, I wasn’t doing an actual controlled experiment.

Applying spent coffee grounds directly to urban agriculture soils greatly reduces plant growth

There are frequent anecdotal recommendations for the use of locally produced spent coffee grounds in urban agriculture and gardens, either through direct soil application or after composting with other urban organic wastes. This study investigates the scientific basis for direct application of spent coffee grounds (SCG) and the influence of different: i) plant pH and nitrogen preferences, ii) soil types, and iii) application rates. We specifically consider impacts upon plant growth, soil hydrology and nitrogen transformation processes.

We grew five horticultural plants (broccoli, leek, radish, viola and sunflower) in sandy, sandy clay loam and loam soils, with and without SCG and fertilizer amendments. The same horticultural plants were grown in the field with 0, 2.5, 5, 10 and 25% SCG amendment rates. Plant biomass growth was related to soil pH, soil moisture, nitrogen concentration and net mineralization, as was weed growth after harvesting.

All horticultural plants grew poorly in response to SCG, regardless of soil type and fertiliser addition. Increasing SCG amendment significantly increased soil water holding capacity, but also decreased horticultural plant growth and subsequent weed growth. There was evidence of nitrate immobilization with SCG amendment. Growth suppression was not explained by soil pH change, or nitrogen availability, so is more likely due to phytotoxic effects.

Fresh SCG should not be used as a soil amendment in ‘closed loop’ urban food production systems without consideration of potential growth suppression. Further research is required to determine the optimal composting conditions for SCG and blends with other organic wastes.

I’m not a very scientific composter. I just throw stuff together in an old recycling bin, then when it fills up I move it to another bin, and then a third (despite a few raised eyebrows from neighbors, I rescued all these bins on my old street after they were abandoned for at least a week, and filled with litter and dog crap). At that point it’s usually a nice crumbly organic mix that I can use. I don’t follow any of the rules. I don’t mix green and brown items in the right proportions, I let it get wet and dry according to the rain, I compost perennial weeds, and my pile almost certainly doesn’t get hot enough. I probably wouldn’t give the stuff away because there are weeds in there, but I don’t worry about putting it back on my garden, which is where the weeds came from. If they want to keep pulling carbon dioxide out of the air and turning it into organic matter for me, I am fine with that. I would rather be outside pulling weeds than doing almost anything inside.

1 billion dogs

I never thought to even wonder how many dogs there are in the world. But according to this article, about a billion. I don’t know if that is morally right or wrong. I like dogs. They are generally benign, kind-hearted creatures, and you could certainly make an argument that the world would not be as good a place without them. But they certainly have an ecological footprint. The article contrasts dogs and wolves, which have been systematically eradicated in many cases. So while dogs are neat creatures in many ways there are probably many wild creatures that might exist out there if they did not. Now we could examine this same moral conundrum with respect to a certain species of intelligent hairless ape…

“hybrid” infrastructure

I like a couple things in this abstract from the journal Cities.

One is a definition of hybrid infrastructure as “infrastructure systems that are integrated within buildings and landscapes that also provide non-infrastructure uses”. In other words, you are trying to kill two birds with one stone. This should be efficient and cost-effective compared to killing two birds with two stones, but the reason it often doesn’t happen (at least in the U.S. cities I am familiar with) is that there are typically two entities responsible for killing one bird each, and if their stone happens to kill the other bird they will ignore that and not count it as a benefit. Each agency calculates the cost as one stone, while the actual cost to society was two stones. (The only problem with this analogy, obviously, is that we are talking about ecological benefits and killing birds would actually be bad.)

The second thing I like is that the question asked is about the “maximum ecological performance potential of buildings and landscapes”. This is a nice question to ask – not just how can one type of infrastructure perform one function cost-effectively, but how can it fit into the landscape and perform many functions at the same time. If those two agencies (or in real life, 10 or 20 agencies) were all asking this question together, maybe you could achieve much better outcomes in cities.