TEXT II – Questions 25 to 29

NEW LAB TO FOCUS ON CREATING SUSTAINABLE ENERGY SOURCE

Research will explore using sunlight to convert greenhouse gas carbon dioxide and water to syngas, the precursor to liquid fuel.

A state-of-the-art laboratory, which aims to use sunlight to power the sustainable conversion of CO₂ and water to form syngas, a high-energy gas mixture with potential as a future fuel source, opened this week in the Department of Chemistry.

The Christian Doppler laboratory for Sustainable SynGas Chemistry will address application-oriented basic research questions to facilitate the creation of a sustainable carbon-based economy. It is jointly funded by the Austrian Christian Doppler Research Association (Federal Ministry of Economy, Family and Youth & the National Foundation for Research, Technology and Development) and the OMV Group for a period of seven years.

The lab will research ways to use light from the sun to power the sustainable conversion of the greenhouse gas carbon dioxide and water to form syngas, a highenergy gas mixture containing hydrogen, H₂ (an attractive fuel on its own), and carbon monoxide, CO. Syngas is a valuable gas mixture and, importantly, it can be transformed into liquid hydrocarbons (‘gasoline’), also known as liquid fuels.

Despite its potential as a future fuel source, syngas is already used as an invaluable chemical feedstock for the petrochemical industry, as an intermediate for the production of many chemicals such as H₂, methanol and ammonia. Unfortunately, current production of syngas is nonrenewable; it is produced on a mega-ton scale by the energy-intensive steam reforming of fossil fuels, and subsequent H₂ to CO ratio adjustment by the water-gas shift reaction. This unsustainable process yields fuel cell grade H₂ and the greenhouse gas CO₂.

Dr Erwin Reisner, Head of the Christian Doppler Laboratory, said: “The approach of the new laboratory aims to develop the basic principles to allow for a renewable production of syngas. Our longterm vision is a transition from a fossil-based to a sustainable carbon-based economy.”

The CD-laboratory will focus on developing molecular catalysts, which will ultimately be integrated in nanostructured materials for syngas generation. This approach will allow for the assembly of a small-scale device for solar syngas production. The CDlaboratory will operate with an exceptional cross-disciplinary approach at the interface of bio-inspired molecular and materials synthesis, advanced electrochemistry, photochemistry and nanodevice engineering. The proposed research project combines a high degree of novelty with potentially enormous impact on academic science, industry and society.

The Christian Doppler Research Association is a non-profit organization that supports basic science and technology to economically relevant questions. The OMV Group is an Austrian-based oil refining company with important global activities.

Source: University of Cambridge - http://www.cam.ac.uk

TEXT II – Questions 25 to 29

NEW LAB TO FOCUS ON CREATING SUSTAINABLE ENERGY SOURCE

Research will explore using sunlight to convert greenhouse gas carbon dioxide and water to syngas, the precursor to liquid fuel.

A state-of-the-art laboratory, which aims to use sunlight to power the sustainable conversion of CO₂ and water to form syngas, a high-energy gas mixture with potential as a future fuel source, opened this week in the Department of Chemistry.

The Christian Doppler laboratory for Sustainable SynGas Chemistry will address application-oriented basic research questions to facilitate the creation of a sustainable carbon-based economy. It is jointly funded by the Austrian Christian Doppler Research Association (Federal Ministry of Economy, Family and Youth & the National Foundation for Research, Technology and Development) and the OMV Group for a period of seven years.

The lab will research ways to use light from the sun to power the sustainable conversion of the greenhouse gas carbon dioxide and water to form syngas, a highenergy gas mixture containing hydrogen, H₂ (an attractive fuel on its own), and carbon monoxide, CO. Syngas is a valuable gas mixture and, importantly, it can be transformed into liquid hydrocarbons (‘gasoline’), also known as liquid fuels.

Despite its potential as a future fuel source, syngas is already used as an invaluable chemical feedstock for the petrochemical industry, as an intermediate for the production of many chemicals such as H₂, methanol and ammonia. Unfortunately, current production of syngas is nonrenewable; it is produced on a mega-ton scale by the energy-intensive steam reforming of fossil fuels, and subsequent H₂ to CO ratio adjustment by the water-gas shift reaction. This unsustainable process yields fuel cell grade H₂ and the greenhouse gas CO₂.

Dr Erwin Reisner, Head of the Christian Doppler Laboratory, said: “The approach of the new laboratory aims to develop the basic principles to allow for a renewable production of syngas. Our longterm vision is a transition from a fossil-based to a sustainable carbon-based economy.”

The CD-laboratory will focus on developing molecular catalysts, which will ultimately be integrated in nanostructured materials for syngas generation. This approach will allow for the assembly of a small-scale device for solar syngas production. The CDlaboratory will operate with an exceptional cross-disciplinary approach at the interface of bio-inspired molecular and materials synthesis, advanced electrochemistry, photochemistry and nanodevice engineering. The proposed research project combines a high degree of novelty with potentially enormous impact on academic science, industry and society.

The Christian Doppler Research Association is a non-profit organization that supports basic science and technology to economically relevant questions. The OMV Group is an Austrian-based oil refining company with important global activities.

Source: University of Cambridge - http://www.cam.ac.uk

TEXT II – Questions 25 to 29

NEW LAB TO FOCUS ON CREATING SUSTAINABLE ENERGY SOURCE

Research will explore using sunlight to convert greenhouse gas carbon dioxide and water to syngas, the precursor to liquid fuel.

A state-of-the-art laboratory, which aims to use sunlight to power the sustainable conversion of CO₂ and water to form syngas, a high-energy gas mixture with potential as a future fuel source, opened this week in the Department of Chemistry.

The Christian Doppler laboratory for Sustainable SynGas Chemistry will address application-oriented basic research questions to facilitate the creation of a sustainable carbon-based economy. It is jointly funded by the Austrian Christian Doppler Research Association (Federal Ministry of Economy, Family and Youth & the National Foundation for Research, Technology and Development) and the OMV Group for a period of seven years.

The lab will research ways to use light from the sun to power the sustainable conversion of the greenhouse gas carbon dioxide and water to form syngas, a highenergy gas mixture containing hydrogen, H₂ (an attractive fuel on its own), and carbon monoxide, CO. Syngas is a valuable gas mixture and, importantly, it can be transformed into liquid hydrocarbons (‘gasoline’), also known as liquid fuels.

Despite its potential as a future fuel source, syngas is already used as an invaluable chemical feedstock for the petrochemical industry, as an intermediate for the production of many chemicals such as H₂, methanol and ammonia. Unfortunately, current production of syngas is nonrenewable; it is produced on a mega-ton scale by the energy-intensive steam reforming of fossil fuels, and subsequent H₂ to CO ratio adjustment by the water-gas shift reaction. This unsustainable process yields fuel cell grade H₂ and the greenhouse gas CO₂.

Dr Erwin Reisner, Head of the Christian Doppler Laboratory, said: “The approach of the new laboratory aims to develop the basic principles to allow for a renewable production of syngas. Our longterm vision is a transition from a fossil-based to a sustainable carbon-based economy.”

The CD-laboratory will focus on developing molecular catalysts, which will ultimately be integrated in nanostructured materials for syngas generation. This approach will allow for the assembly of a small-scale device for solar syngas production. The CDlaboratory will operate with an exceptional cross-disciplinary approach at the interface of bio-inspired molecular and materials synthesis, advanced electrochemistry, photochemistry and nanodevice engineering. The proposed research project combines a high degree of novelty with potentially enormous impact on academic science, industry and society.

The Christian Doppler Research Association is a non-profit organization that supports basic science and technology to economically relevant questions. The OMV Group is an Austrian-based oil refining company with important global activities.

Source: University of Cambridge - http://www.cam.ac.uk

TEXT II – Questions 25 to 29

NEW LAB TO FOCUS ON CREATING SUSTAINABLE ENERGY SOURCE

Research will explore using sunlight to convert greenhouse gas carbon dioxide and water to syngas, the precursor to liquid fuel.

A state-of-the-art laboratory, which aims to use sunlight to power the sustainable conversion of CO₂ and water to form syngas, a high-energy gas mixture with potential as a future fuel source, opened this week in the Department of Chemistry.

The Christian Doppler laboratory for Sustainable SynGas Chemistry will address application-oriented basic research questions to facilitate the creation of a sustainable carbon-based economy. It is jointly funded by the Austrian Christian Doppler Research Association (Federal Ministry of Economy, Family and Youth & the National Foundation for Research, Technology and Development) and the OMV Group for a period of seven years.

The lab will research ways to use light from the sun to power the sustainable conversion of the greenhouse gas carbon dioxide and water to form syngas, a highenergy gas mixture containing hydrogen, H₂ (an attractive fuel on its own), and carbon monoxide, CO. Syngas is a valuable gas mixture and, importantly, it can be transformed into liquid hydrocarbons (‘gasoline’), also known as liquid fuels.

Despite its potential as a future fuel source, syngas is already used as an invaluable chemical feedstock for the petrochemical industry, as an intermediate for the production of many chemicals such as H₂, methanol and ammonia. Unfortunately, current production of syngas is nonrenewable; it is produced on a mega-ton scale by the energy-intensive steam reforming of fossil fuels, and subsequent H₂ to CO ratio adjustment by the water-gas shift reaction. This unsustainable process yields fuel cell grade H₂ and the greenhouse gas CO₂.

Dr Erwin Reisner, Head of the Christian Doppler Laboratory, said: “The approach of the new laboratory aims to develop the basic principles to allow for a renewable production of syngas. Our longterm vision is a transition from a fossil-based to a sustainable carbon-based economy.”

The CD-laboratory will focus on developing molecular catalysts, which will ultimately be integrated in nanostructured materials for syngas generation. This approach will allow for the assembly of a small-scale device for solar syngas production. The CDlaboratory will operate with an exceptional cross-disciplinary approach at the interface of bio-inspired molecular and materials synthesis, advanced electrochemistry, photochemistry and nanodevice engineering. The proposed research project combines a high degree of novelty with potentially enormous impact on academic science, industry and society.

The Christian Doppler Research Association is a non-profit organization that supports basic science and technology to economically relevant questions. The OMV Group is an Austrian-based oil refining company with important global activities.

Source: University of Cambridge - http://www.cam.ac.uk

TEXT II – Questions 25 to 29

NEW LAB TO FOCUS ON CREATING SUSTAINABLE ENERGY SOURCE

Research will explore using sunlight to convert greenhouse gas carbon dioxide and water to syngas, the precursor to liquid fuel.

A state-of-the-art laboratory, which aims to use sunlight to power the sustainable conversion of CO₂ and water to form syngas, a high-energy gas mixture with potential as a future fuel source, opened this week in the Department of Chemistry.

The Christian Doppler laboratory for Sustainable SynGas Chemistry will address application-oriented basic research questions to facilitate the creation of a sustainable carbon-based economy. It is jointly funded by the Austrian Christian Doppler Research Association (Federal Ministry of Economy, Family and Youth & the National Foundation for Research, Technology and Development) and the OMV Group for a period of seven years.

The lab will research ways to use light from the sun to power the sustainable conversion of the greenhouse gas carbon dioxide and water to form syngas, a highenergy gas mixture containing hydrogen, H₂ (an attractive fuel on its own), and carbon monoxide, CO. Syngas is a valuable gas mixture and, importantly, it can be transformed into liquid hydrocarbons (‘gasoline’), also known as liquid fuels.

Despite its potential as a future fuel source, syngas is already used as an invaluable chemical feedstock for the petrochemical industry, as an intermediate for the production of many chemicals such as H₂, methanol and ammonia. Unfortunately, current production of syngas is nonrenewable; it is produced on a mega-ton scale by the energy-intensive steam reforming of fossil fuels, and subsequent H₂ to CO ratio adjustment by the water-gas shift reaction. This unsustainable process yields fuel cell grade H₂ and the greenhouse gas CO₂.

Dr Erwin Reisner, Head of the Christian Doppler Laboratory, said: “The approach of the new laboratory aims to develop the basic principles to allow for a renewable production of syngas. Our longterm vision is a transition from a fossil-based to a sustainable carbon-based economy.”

The CD-laboratory will focus on developing molecular catalysts, which will ultimately be integrated in nanostructured materials for syngas generation. This approach will allow for the assembly of a small-scale device for solar syngas production. The CDlaboratory will operate with an exceptional cross-disciplinary approach at the interface of bio-inspired molecular and materials synthesis, advanced electrochemistry, photochemistry and nanodevice engineering. The proposed research project combines a high degree of novelty with potentially enormous impact on academic science, industry and society.

The Christian Doppler Research Association is a non-profit organization that supports basic science and technology to economically relevant questions. The OMV Group is an Austrian-based oil refining company with important global activities.

Source: University of Cambridge - http://www.cam.ac.uk

TEXT I – Questions 21 to 24

WHY WAVE OF MEXICAN IMMIGRATION STOPPED

_{By Jeffrey S. Passel and D'Vera Cohn, Special to CNN April 26, 2012}

Our analysis of Mexican and U.S. data sources indicates that at least as many Mexicans and their families are leaving the United States as are arriving in the United States from Mexico. As a result, the Mexicanborn population in the United States decreased from 12.6 million in 2007 to 12 million in 2011. This appears to be the first sustained decline in the number of Mexican immigrants since the Great Depression, and it is entirely because of a reduction in illegal immigration -- more going home and fewer coming. Today, we estimate that 51% of all Mexican immigrants living in the United States are unauthorized. In 2007, that figure was 56%.

Even with the recent decline, Mexicans are still by far the largest single immigrant group in the United States, accounting for 30% of the foreign-born. The population of Mexican immigrants in the United States is larger than that of most countries or states: 10% of Mexican-born people worldwide live in the United States. No other nation in the world has as many of its people living abroad as does Mexico.

What caused the big immigration wave to stop? We think that many factors were at work, on both sides of the border. We cannot say how much of a role each of them played in tamping down migration to the United States and setting up the large reverse flows, but they all seem to have had an impact.

The sharp decline began about five years ago, around the time the U.S. housing market collapsed. Many construction jobs held by Mexican immigrants vanished. The continued weakness in the overall U.S. economy made it harder to find other jobs as well. Although the Great Recession has officially ended, the job market is not back to what it was.

During these same years, U.S. officials have heightened enforcement of immigration laws along the border and elsewhere. Unauthorized border-crossers have faced harsher penalties, and deportations have risen. We estimate that anywhere from 5% to 35% of the Mexicans who went home over the past five years did so involuntarily.

Six states, including Arizona, have passed laws intended to reduce unauthorized immigration. For these and other reasons, it has become more dangerous to try to cross the border from Mexico.

Developments on the Mexican side of the border also could be affecting migration flows. Mexico's economy, like that in the United States, fell into a deep recession from 2007 to 2009. But in 2010 and 2011, the Gross Domestic Product there grew at higher rates than the U.S. GDP, so Mexicans enjoyed a somewhat stronger recovery that may have encouraged some to stay home and others to return.

Another change in Mexico that is just beginning to affect migration streams is a steep decline in birth rates. In 1960, the fertility rate in Mexico was 7.3 -- meaning, on average, a Mexican woman could expect to have seven children in her lifetime. In 2009, it had dropped to 2.4. Declining birth rates have pushed up the median age of the Mexican population. This has meant that the age group in the prime years for emigration, 15- to 39- year-olds, is a shrinking share of Mexico's population.

Will the net standstill in migration from Mexico continue? We do not know, in part because of uncertainties about economic trends in both nations and future trends in enforcement policies. The decline in Mexican birth rates, however, does appear to be a long-term change that will limit the size of the pool of young people who are the most likely to emigrate.

But even if Mexican immigration does begin to rise again, consider how far it has fallen. From 1995 through 2000, we estimate that 3 million Mexicans moved to the United States, and nearly 700,000, including family members born in the United States, went home. From 2005 through 2010, we estimate that about 1.4 million Mexicans arrived, and the same number, including U.S.-born children, left. Considering everything, a return to the migration levels of the late 1990s now seems inconceivable.

Source: http://edition.cnn.com

TEXT I – Questions 21 to 24

WHY WAVE OF MEXICAN IMMIGRATION STOPPED

_{By Jeffrey S. Passel and D'Vera Cohn, Special to CNN April 26, 2012}

Our analysis of Mexican and U.S. data sources indicates that at least as many Mexicans and their families are leaving the United States as are arriving in the United States from Mexico. As a result, the Mexicanborn population in the United States decreased from 12.6 million in 2007 to 12 million in 2011. This appears to be the first sustained decline in the number of Mexican immigrants since the Great Depression, and it is entirely because of a reduction in illegal immigration -- more going home and fewer coming. Today, we estimate that 51% of all Mexican immigrants living in the United States are unauthorized. In 2007, that figure was 56%.

Even with the recent decline, Mexicans are still by far the largest single immigrant group in the United States, accounting for 30% of the foreign-born. The population of Mexican immigrants in the United States is larger than that of most countries or states: 10% of Mexican-born people worldwide live in the United States. No other nation in the world has as many of its people living abroad as does Mexico.

What caused the big immigration wave to stop? We think that many factors were at work, on both sides of the border. We cannot say how much of a role each of them played in tamping down migration to the United States and setting up the large reverse flows, but they all seem to have had an impact.

The sharp decline began about five years ago, around the time the U.S. housing market collapsed. Many construction jobs held by Mexican immigrants vanished. The continued weakness in the overall U.S. economy made it harder to find other jobs as well. Although the Great Recession has officially ended, the job market is not back to what it was.

During these same years, U.S. officials have heightened enforcement of immigration laws along the border and elsewhere. Unauthorized border-crossers have faced harsher penalties, and deportations have risen. We estimate that anywhere from 5% to 35% of the Mexicans who went home over the past five years did so involuntarily.

Six states, including Arizona, have passed laws intended to reduce unauthorized immigration. For these and other reasons, it has become more dangerous to try to cross the border from Mexico.

Developments on the Mexican side of the border also could be affecting migration flows. Mexico's economy, like that in the United States, fell into a deep recession from 2007 to 2009. But in 2010 and 2011, the Gross Domestic Product there grew at higher rates than the U.S. GDP, so Mexicans enjoyed a somewhat stronger recovery that may have encouraged some to stay home and others to return.

Another change in Mexico that is just beginning to affect migration streams is a steep decline in birth rates. In 1960, the fertility rate in Mexico was 7.3 -- meaning, on average, a Mexican woman could expect to have seven children in her lifetime. In 2009, it had dropped to 2.4. Declining birth rates have pushed up the median age of the Mexican population. This has meant that the age group in the prime years for emigration, 15- to 39- year-olds, is a shrinking share of Mexico's population.

Will the net standstill in migration from Mexico continue? We do not know, in part because of uncertainties about economic trends in both nations and future trends in enforcement policies. The decline in Mexican birth rates, however, does appear to be a long-term change that will limit the size of the pool of young people who are the most likely to emigrate.

But even if Mexican immigration does begin to rise again, consider how far it has fallen. From 1995 through 2000, we estimate that 3 million Mexicans moved to the United States, and nearly 700,000, including family members born in the United States, went home. From 2005 through 2010, we estimate that about 1.4 million Mexicans arrived, and the same number, including U.S.-born children, left. Considering everything, a return to the migration levels of the late 1990s now seems inconceivable.

Source: http://edition.cnn.com

TEXT I – Questions 21 to 24

WHY WAVE OF MEXICAN IMMIGRATION STOPPED

_{By Jeffrey S. Passel and D'Vera Cohn, Special to CNN April 26, 2012}

Our analysis of Mexican and U.S. data sources indicates that at least as many Mexicans and their families are leaving the United States as are arriving in the United States from Mexico. As a result, the Mexicanborn population in the United States decreased from 12.6 million in 2007 to 12 million in 2011. This appears to be the first sustained decline in the number of Mexican immigrants since the Great Depression, and it is entirely because of a reduction in illegal immigration -- more going home and fewer coming. Today, we estimate that 51% of all Mexican immigrants living in the United States are unauthorized. In 2007, that figure was 56%.

Even with the recent decline, Mexicans are still by far the largest single immigrant group in the United States, accounting for 30% of the foreign-born. The population of Mexican immigrants in the United States is larger than that of most countries or states: 10% of Mexican-born people worldwide live in the United States. No other nation in the world has as many of its people living abroad as does Mexico.

What caused the big immigration wave to stop? We think that many factors were at work, on both sides of the border. We cannot say how much of a role each of them played in tamping down migration to the United States and setting up the large reverse flows, but they all seem to have had an impact.

The sharp decline began about five years ago, around the time the U.S. housing market collapsed. Many construction jobs held by Mexican immigrants vanished. The continued weakness in the overall U.S. economy made it harder to find other jobs as well. Although the Great Recession has officially ended, the job market is not back to what it was.

During these same years, U.S. officials have heightened enforcement of immigration laws along the border and elsewhere. Unauthorized border-crossers have faced harsher penalties, and deportations have risen. We estimate that anywhere from 5% to 35% of the Mexicans who went home over the past five years did so involuntarily.

Six states, including Arizona, have passed laws intended to reduce unauthorized immigration. For these and other reasons, it has become more dangerous to try to cross the border from Mexico.

Developments on the Mexican side of the border also could be affecting migration flows. Mexico's economy, like that in the United States, fell into a deep recession from 2007 to 2009. But in 2010 and 2011, the Gross Domestic Product there grew at higher rates than the U.S. GDP, so Mexicans enjoyed a somewhat stronger recovery that may have encouraged some to stay home and others to return.

Another change in Mexico that is just beginning to affect migration streams is a steep decline in birth rates. In 1960, the fertility rate in Mexico was 7.3 -- meaning, on average, a Mexican woman could expect to have seven children in her lifetime. In 2009, it had dropped to 2.4. Declining birth rates have pushed up the median age of the Mexican population. This has meant that the age group in the prime years for emigration, 15- to 39- year-olds, is a shrinking share of Mexico's population.

Will the net standstill in migration from Mexico continue? We do not know, in part because of uncertainties about economic trends in both nations and future trends in enforcement policies. The decline in Mexican birth rates, however, does appear to be a long-term change that will limit the size of the pool of young people who are the most likely to emigrate.

But even if Mexican immigration does begin to rise again, consider how far it has fallen. From 1995 through 2000, we estimate that 3 million Mexicans moved to the United States, and nearly 700,000, including family members born in the United States, went home. From 2005 through 2010, we estimate that about 1.4 million Mexicans arrived, and the same number, including U.S.-born children, left. Considering everything, a return to the migration levels of the late 1990s now seems inconceivable.

Source: http://edition.cnn.com

TEXT I – Questions 21 to 24

WHY WAVE OF MEXICAN IMMIGRATION STOPPED

_{By Jeffrey S. Passel and D'Vera Cohn, Special to CNN April 26, 2012}

Our analysis of Mexican and U.S. data sources indicates that at least as many Mexicans and their families are leaving the United States as are arriving in the United States from Mexico. As a result, the Mexicanborn population in the United States decreased from 12.6 million in 2007 to 12 million in 2011. This appears to be the first sustained decline in the number of Mexican immigrants since the Great Depression, and it is entirely because of a reduction in illegal immigration -- more going home and fewer coming. Today, we estimate that 51% of all Mexican immigrants living in the United States are unauthorized. In 2007, that figure was 56%.

Even with the recent decline, Mexicans are still by far the largest single immigrant group in the United States, accounting for 30% of the foreign-born. The population of Mexican immigrants in the United States is larger than that of most countries or states: 10% of Mexican-born people worldwide live in the United States. No other nation in the world has as many of its people living abroad as does Mexico.

What caused the big immigration wave to stop? We think that many factors were at work, on both sides of the border. We cannot say how much of a role each of them played in tamping down migration to the United States and setting up the large reverse flows, but they all seem to have had an impact.

The sharp decline began about five years ago, around the time the U.S. housing market collapsed. Many construction jobs held by Mexican immigrants vanished. The continued weakness in the overall U.S. economy made it harder to find other jobs as well. Although the Great Recession has officially ended, the job market is not back to what it was.

During these same years, U.S. officials have heightened enforcement of immigration laws along the border and elsewhere. Unauthorized border-crossers have faced harsher penalties, and deportations have risen. We estimate that anywhere from 5% to 35% of the Mexicans who went home over the past five years did so involuntarily.

Six states, including Arizona, have passed laws intended to reduce unauthorized immigration. For these and other reasons, it has become more dangerous to try to cross the border from Mexico.

Developments on the Mexican side of the border also could be affecting migration flows. Mexico's economy, like that in the United States, fell into a deep recession from 2007 to 2009. But in 2010 and 2011, the Gross Domestic Product there grew at higher rates than the U.S. GDP, so Mexicans enjoyed a somewhat stronger recovery that may have encouraged some to stay home and others to return.

Another change in Mexico that is just beginning to affect migration streams is a steep decline in birth rates. In 1960, the fertility rate in Mexico was 7.3 -- meaning, on average, a Mexican woman could expect to have seven children in her lifetime. In 2009, it had dropped to 2.4. Declining birth rates have pushed up the median age of the Mexican population. This has meant that the age group in the prime years for emigration, 15- to 39- year-olds, is a shrinking share of Mexico's population.

Will the net standstill in migration from Mexico continue? We do not know, in part because of uncertainties about economic trends in both nations and future trends in enforcement policies. The decline in Mexican birth rates, however, does appear to be a long-term change that will limit the size of the pool of young people who are the most likely to emigrate.

But even if Mexican immigration does begin to rise again, consider how far it has fallen. From 1995 through 2000, we estimate that 3 million Mexicans moved to the United States, and nearly 700,000, including family members born in the United States, went home. From 2005 through 2010, we estimate that about 1.4 million Mexicans arrived, and the same number, including U.S.-born children, left. Considering everything, a return to the migration levels of the late 1990s now seems inconceivable.

Source: http://edition.cnn.com