Urbanization: 95% Of The World's Population Lives On 10% Of The Land

ScienceDaily (Dec. 19, 2008) — A new global map released by the European Commission's Joint Research Centre and published in the World Bank’s World Development Report 2009, measures urbanisation from the new perspective of Travel Time to 8,500 Major Cities. The map fills an important gap in our understanding of economic, physical and even social connectivity.




n the absence of agreement on the meaning of "urbanisation", the European Commission and the World Bank are proposing a new definition based on a unique mapping of “Accessibility” called the Agglomeration Index.

Key findings suggest that:

* we passed the point at which more than half the world’s populations live in cities around the turn of the Millennium (2000) - much earlier than the 2007/8 estimate;
* more than half of the world's population lives less than 1 hour from a major city, but the breakdown is 85% of the developed world and only 35% of the developing world;
* 95% of the world's population is concentrated on just 10% of the world's land; but
* only 10% of the world's land area is classified as "remote" or more than 48 hours from a large city.

Leen Hordijk, Director of the Institute for Environment and Sustainability of the EC's Joint Research Centre, whose scientists prepared the new map, commented: "We have risen to the challenge of combining various information sources with the latest mapping technologies to produce a unique and timely product for the World Bank. Our map raises the question: For how much longer will remote ecosystems remain remote? Many are crucial to the healthy functioning of our planet."

How does the mapping work?

Digital maps of road, river and rail transport networks, population data, satellite-derived maps of land cover and terrain and information on border crossing times are combined using advanced geographical modelling techniques. For example, the time it takes an individual to travel to a city from 100 km away is calculated from precise knowledge of the terrain he or she must cross whether it is by foot, road, rail or river.

Taking scientists twelve months to complete, the result is a global map of travel time to over 8,500 major cities. This, in turn, allows scientists to establish a new globally consistent measure - the Agglomeration Index - which will facilitate the work of the World Bank and other international organisations when monitoring the effects of urbanisation.

The world's population is concentrating in cities

The human population is more concentrated than ever before. Europe’s urban sprawl gradually fades as we move eastwards into the steppes of central Asia, soon to re-emerge into the dense networks of people and places in India, China and Japan. The attraction of Australia’s coasts is dramatically revealed, while North America appears to adopt a grid system not just for its streets and road networks, but for distribution of the cities themselves.

Cities exercise enormous control over national economies - even the global economy. They provide jobs, access to the best cultural, educational and health facilities and they act as hubs for communication and transport. Of course, they also cluster massive demands for energy, generate large quantities of waste, and concentrate pollution as well as social hardship.

Redefining 'urban'

By using travel-time as a unit of measurement, the map of Travel Time to Major Cities represents accessibility through the easily understood concept of “how long will it take to get there?” Accessibility links people with places, goods with markets and communities to vital services. Accessibility - whether it is to markets, schools, hospitals or water - is a precondition for the satisfaction of almost any economic need. Furthermore, accessibility is relevant at all levels, from local development to global trade.

Because of advances in transport systems and networks we are better connected than ever before. This new map demonstrates how accessible some parts of the world are, indicating increased opportunities for travel, trade, communication and interaction.

This map also serves as a stark reminder that the price of greater connectivity is that there is little wilderness left. While only 10% of the world is more than 48 hours from a large city, our wilderness has shrunk to the highest of the mountains, such as the Plateau of Tibet and the extremes of the high latitudes, such as the boreal forests and ice sheets. Even the deserts and tropical forests are not the inaccessible wild lands they once were.
Adapted from materials provided by European Commission, Joint Research Centre (JRC).



Breakthrough In Generating Novel Types Of Stem Cells

ScienceDaily (Dec. 19, 2008) — A team led by Scripps Research Institute scientists has for the first time developed a technique for generating novel types of rat and human stem cells with characteristics similar to mouse embryonic stem cells, currently the predominant type of stem cells used for creating animal models of human diseases in research. The technique potentially provides scientists with new sources of stem cells to develop drugs and treatments for human diseases.

The study, which appears in the December 18 online version of Cell Stem Cell and the January 2009 print edition of the journal, provides proof of principle that alternative sources of stem cells can be created.

The team, which included scientists from Scripps Research, Peking University, and the University of California, San Diego, conducted the studies to establish novel rat induced pluripotent stem cell lines (riPSCs) and human induced pluripotent stem cell lines (hiPSCs) by using a specific cocktail of chemicals combined with genetic reprogramming, a process whereby an adult cell is returned to its early embryonic state. Pluripotency refers to the ability of a cell to develop into each of the more than 200 cell types of the adult body.

Mimicking Human Physiology

Scientists genetically engineer embryonic stem cells to create mouse models that contain the engineered genes—so-called transgenic animals—in the hope of applying the knowledge gained from studying such mice to benefit humans. Although using mouse pluripotent embryonic stem cells has been the standard since these cells were first derived in 1981, researchers have long wanted to apply such powerful techniques to other animal species to help the study of human physiology and disease.

The major advantage of using other animal species, such as rats, is that the physiology of these animals can better mimic human physiology, for example, in studies of metabolic and neurological diseases. The size of other animals also is an advantage because larger organs and tissues are easier to work with. Because of these benefits, scientists have created transgenic animals from species other than mice, but the lack of pluripotent stem cells from these species and the tedious and imprecise techniques currently available has made the process difficult.

"Mouse models created with pluripotent embryonic stem cells are wonderful tools for understanding the fundamental biology of genes," says Sheng Ding, Ph.D., an associate professor in the Scripps Research Department of Chemistry who was senior author of the study with Peking University investigator Hongkui Deng, Ph.D. "But in some important ways these models are less than ideal. Our demonstrated technologies will enable unprecedented and broad applications for better creating animal models from other species."

Novel and More Robust Human Pluripotent Stem Cells

In another closely related aspect of this work, Ding has also shown that a new kind of human pluripotent stem cell can now be created using the same chemical and reprogramming methods used to create the rat pluripotent stem cells. Human pluripotent stem cells hold promise for modeling human development and disease, testing drugs, and providing unlimited functional cells for cell replacement therapy.

"Recent studies have found, however, that conventional human embryonic stem cells represent a different pluripotent cell type and are not the counterpart of the conventional, and most useful, mouse embryonic stem cells," Ding says.

The issue is that pluripotent stem cells can be represented by cells from two distinct stages of embryonic development—the early pre-implantation blastocyst stage and the later post-implantation epiblast stage. Today, conventional mouse embryonic stem cells represent the pre- implantation stage pluripotent cells, and human embryonic stem cells appear to represent later post- implantation stage pluripotent cells.

Early- and late-stage cells have very different properties. For example, they respond differently to the same signals given to stem cells to differentiate into specific types of cells. The pre-implantation stage of cells will differentiate into one type of cell, while post-implantation stage of cells will turn into other types of cells. Their propensity toward specific cell types and growth properties are also different. The novel human pluripotent cells created by the scientists appear to represent the early stage of pluripotent cells—closer to well researched conventional mouse embryonic stem cells—and grow with better properties.

"The different behaviors of the pre- and post-implantation pluripotent stem cells means that findings from research done on mouse embryonic stem cells are often not translatable to work done on human embryonic stem cells," Ding says. "With our new human pluripotent stem cells, we again have proof of principle that human stem cells can be created that are similar to mouse embryonic stem cells. The knowledge gained from mouse studies, therefore, will be more directly translatable to human cells, offering an advantage in biomedical research."

In addition to Ding and Deng, other authors of the study, "Generation of novel rat and human pluripotent stem cells with mouse embryonic stem cell characteristics by reprogramming and chemical approach," are Wenlin Li (first author), Saiyong Zhu, Yan Shi, Tongxiang Lin, of Scripps Research; Wei Wei and Jinliang Zhu of the College of Life Sciences, Peking University, China; and Ergeng Hao and Alberto Hayek of the University of California, San Diego.
Adapted from materials provided by Scripps Research Institute, via EurekAlert!, a service of AAAS.





Biological Weapons Show Promise In Onion Growers' Long Battle Against A Plague Of Maggots, Cornell Researchers Say

ScienceDaily (Mar. 12, 1999) — ITHACA, N.Y. -- The leading enemy of New York state's fall onion harvest is a fly with the Latin name, "Delia antiqua". Onion growers just call its immature stage the onion maggot and for two decades it increasingly has been wreaking economic havoc in the state's onion fields.




New York's 12,000 acres of commercial onion fields annually produce a crop with a value of between $50 million and $75 million. If a field gets infested with the maggot, between 20 percent and 90 percent of unprotected onion seedlings can be wiped out.

Until now the maggot has resisted attempts at control. But Cornell University agricultural researchers are reporting that two biological tools are showing promise in field tests against the onion maggot: a fungus called "Beauveria bassiania" and a bacterium known as "Bacillus thuringiensis "(Bt).

"The research is encouraging," says Charles J. Eckenrode Jr., professor of entomology and researcher at Cornell's New York State Agricultural Experiment Station in Geneva, N.Y. "We've had very good success in the laboratory and Jan van der Heide had good results in the field. "Beauveria" looks exciting, but we have to work out more details." Van der Heide is a Cornell Cooperative Extension (CCE) agent in Oswego County, N.Y.

Cornell laboratory experiments have shown that when "Beauveria", commercially available as Mycotrol ES, made by Mycotech, is sprayed on seedlings, onion maggot damage is reduced to 8.1 percent from 30.3 percent in untreated plots. The researchers believe that this is the result of increased fly mortality and thus leaves fewer maggots on the seedlings. "We do have evidence that "Beauveria" kills flies, but this is indirect evidence," says van der Heide. The researchers first reported their findings in February at the New York State Vegetable Conference in Syracuse.

In a New York growing season, the onion maggot has three generations. The first is the most destructive because the young plants are very susceptible to maggot damage caused by larval feeding after emergence in late May to early June. Farmers' major line of defense has been soil insecticides, specifically an organophosphate that is applied in the seed furrow at planting. Pyrethroid insecticides are labeled for use on onions, and are sometimes used in an attempt to kill adult onion maggot flies later in the season. Unfortunately, these pyrethroid applications only kill a very small percentage of the flies, because most seek refuge from warm, dry conditions in weedy borders and hedge rows, and consequently spend little time on onion field seedlings.

Since 1996, as an alternative to organophospate, onion growers have received Environmental Protection Agency permission during each growing season to use seed pellets augmented with cyromazine, an insect-growth regulator.

In controlled field plots without soil insecticides, "Beauveria "wiped out the first generation of onion maggots, limiting seasonal damage to between 2 and 10 percent, the point at which the maggots become only a minor nuisance, the Cornell researchers say.

"We still have to learn how to use "Beauveria", and when to use it, thus enabling the growers to reduce their dependence on more conventional pesticides," says Eckenrode. "New control approaches such as Bt and "Beauveria" are urgently needed, so we must continue to invest significant amounts of research and time and attention on the ones that show promise."

Eckenrode says that "Beauveria" fungi occur naturally and are believed not to affect humans. Flies killed by these fungi can readily be found in homes and gardens each year. "By taking one of nature's epidemics against flies, and using it commercially, we hope to speed up the process," Eckenrode says.

In New York, onions are grown very intensively in a highly organic, peat-type soil, known in the industry as muck. This usually requires a yearly grower investment of $3,000 to $3,500 an acre before harvest. The muck soil holds water well and allows the onion bulbs to expand. Even in this favorable environment, plant nutrients must be added at strategic times, and a wide array of pests -- including the onion maggot -- plant diseases and weeds must be controlled.

Cornell researchers recommend that growers rotate out of onions, if they can. One possibility for rotation is sorghum sudan grass. Planting it not only breaks the maggot's life cycle, but reduces the nematode population in the muck soil. The grass roots also aerate the ground, allowing increased onion harvests in subsequent growing seasons.

Laboratory and field work discussed here were conducted by Eckenrode and van der Heide; Mary-Lou Hessney, entomologist at the Geneva Experiment Station; Kathleen Hahn, CCE researcher in Oswego County; Mark Ramos, USDA Agricultural Research Service; and John Dunsmoor, an onion grower in Oswego.

Related World Wide Web sites: The following sites provide additional information on this news release.

Cornell College of Agriculture and Life Sciences: http://www.cals.cornell.edu

Adapted from materials provided by Cornell University.