Author: Dr Nasser Afify
Publisher: Independently Published
ISBN: 9781793441492
Category : Technology & Engineering
Languages : en
Pages : 130
Book Description
The fifth industrial revolution is the revolution of nanotechnology. Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers. Nanoscience and nanotechnology are the study and application of extremely small things and can be used across all the other science fields, such as chemistry, biology, physics, materials science, and engineering.The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled "There's Plenty of Room at the Bottom" by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning tunneling microscope that could "see" individual atoms that modern nanotechnology began.It's hard to imagine just how small nanotechnology is. One nanometer is a billionth of a meter, or 10-9 of a meter. Here are a few illustrative examples: There are 25,400,000 nanometers in an inch. A sheet of newspaper is about 100,000 nanometers thick. On a comparative scale, if a marble were a nanometer, then one meter would be the size of the Earth.Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. Everything on Earth is made up of atoms--the food we eat, the clothes we wear, the buildings and houses we live in, and our own bodies. But something as small as an atom is impossible to see with the naked eye. In fact, it's impossible to see with the microscopes typically used in a high school science classes. The microscopes needed to see things at the nanoscale were invented relatively recently--about 30 years ago. Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born.Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn't know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with.Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.
The Nanotechnology: The Fifth Industrial Revolution
Author: Dr Nasser Afify
Publisher: Independently Published
ISBN: 9781793441492
Category : Technology & Engineering
Languages : en
Pages : 130
Book Description
The fifth industrial revolution is the revolution of nanotechnology. Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers. Nanoscience and nanotechnology are the study and application of extremely small things and can be used across all the other science fields, such as chemistry, biology, physics, materials science, and engineering.The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled "There's Plenty of Room at the Bottom" by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning tunneling microscope that could "see" individual atoms that modern nanotechnology began.It's hard to imagine just how small nanotechnology is. One nanometer is a billionth of a meter, or 10-9 of a meter. Here are a few illustrative examples: There are 25,400,000 nanometers in an inch. A sheet of newspaper is about 100,000 nanometers thick. On a comparative scale, if a marble were a nanometer, then one meter would be the size of the Earth.Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. Everything on Earth is made up of atoms--the food we eat, the clothes we wear, the buildings and houses we live in, and our own bodies. But something as small as an atom is impossible to see with the naked eye. In fact, it's impossible to see with the microscopes typically used in a high school science classes. The microscopes needed to see things at the nanoscale were invented relatively recently--about 30 years ago. Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born.Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn't know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with.Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.
Publisher: Independently Published
ISBN: 9781793441492
Category : Technology & Engineering
Languages : en
Pages : 130
Book Description
The fifth industrial revolution is the revolution of nanotechnology. Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers. Nanoscience and nanotechnology are the study and application of extremely small things and can be used across all the other science fields, such as chemistry, biology, physics, materials science, and engineering.The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled "There's Plenty of Room at the Bottom" by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning tunneling microscope that could "see" individual atoms that modern nanotechnology began.It's hard to imagine just how small nanotechnology is. One nanometer is a billionth of a meter, or 10-9 of a meter. Here are a few illustrative examples: There are 25,400,000 nanometers in an inch. A sheet of newspaper is about 100,000 nanometers thick. On a comparative scale, if a marble were a nanometer, then one meter would be the size of the Earth.Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. Everything on Earth is made up of atoms--the food we eat, the clothes we wear, the buildings and houses we live in, and our own bodies. But something as small as an atom is impossible to see with the naked eye. In fact, it's impossible to see with the microscopes typically used in a high school science classes. The microscopes needed to see things at the nanoscale were invented relatively recently--about 30 years ago. Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born.Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn't know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with.Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.
The Fourth Industrial Revolution
Author: Klaus Schwab
Publisher: Crown Currency
ISBN: 1524758876
Category : Business & Economics
Languages : en
Pages : 194
Book Description
World-renowned economist Klaus Schwab, Founder and Executive Chairman of the World Economic Forum, explains that we have an opportunity to shape the fourth industrial revolution, which will fundamentally alter how we live and work. Schwab argues that this revolution is different in scale, scope and complexity from any that have come before. Characterized by a range of new technologies that are fusing the physical, digital and biological worlds, the developments are affecting all disciplines, economies, industries and governments, and even challenging ideas about what it means to be human. Artificial intelligence is already all around us, from supercomputers, drones and virtual assistants to 3D printing, DNA sequencing, smart thermostats, wearable sensors and microchips smaller than a grain of sand. But this is just the beginning: nanomaterials 200 times stronger than steel and a million times thinner than a strand of hair and the first transplant of a 3D printed liver are already in development. Imagine “smart factories” in which global systems of manufacturing are coordinated virtually, or implantable mobile phones made of biosynthetic materials. The fourth industrial revolution, says Schwab, is more significant, and its ramifications more profound, than in any prior period of human history. He outlines the key technologies driving this revolution and discusses the major impacts expected on government, business, civil society and individuals. Schwab also offers bold ideas on how to harness these changes and shape a better future—one in which technology empowers people rather than replaces them; progress serves society rather than disrupts it; and in which innovators respect moral and ethical boundaries rather than cross them. We all have the opportunity to contribute to developing new frameworks that advance progress.
Publisher: Crown Currency
ISBN: 1524758876
Category : Business & Economics
Languages : en
Pages : 194
Book Description
World-renowned economist Klaus Schwab, Founder and Executive Chairman of the World Economic Forum, explains that we have an opportunity to shape the fourth industrial revolution, which will fundamentally alter how we live and work. Schwab argues that this revolution is different in scale, scope and complexity from any that have come before. Characterized by a range of new technologies that are fusing the physical, digital and biological worlds, the developments are affecting all disciplines, economies, industries and governments, and even challenging ideas about what it means to be human. Artificial intelligence is already all around us, from supercomputers, drones and virtual assistants to 3D printing, DNA sequencing, smart thermostats, wearable sensors and microchips smaller than a grain of sand. But this is just the beginning: nanomaterials 200 times stronger than steel and a million times thinner than a strand of hair and the first transplant of a 3D printed liver are already in development. Imagine “smart factories” in which global systems of manufacturing are coordinated virtually, or implantable mobile phones made of biosynthetic materials. The fourth industrial revolution, says Schwab, is more significant, and its ramifications more profound, than in any prior period of human history. He outlines the key technologies driving this revolution and discusses the major impacts expected on government, business, civil society and individuals. Schwab also offers bold ideas on how to harness these changes and shape a better future—one in which technology empowers people rather than replaces them; progress serves society rather than disrupts it; and in which innovators respect moral and ethical boundaries rather than cross them. We all have the opportunity to contribute to developing new frameworks that advance progress.
Nanotechnology
Author: Cherry Bhargava
Publisher: CRC Press
ISBN: 1000197123
Category : Technology & Engineering
Languages : en
Pages : 349
Book Description
Nanotechnology: Advances and Real-Life Applications offers a comprehensive reference text about advanced concepts and applications in the field of nanotechnology. The text – written by researchers practicing in the field – presents a detailed discussion of key concepts including nanomaterials and their synthesis, fabrication and characterization of nanomaterials, carbon-based nanomaterials, nano-bio interface, and nanoelectronics. The applications of nanotechnology in the fields of renewable energy, medicine and agriculture are each covered in a dedicated chapter. The text will be invaluable for senior undergraduate and graduate students in the fields of electrical engineering, electronics engineering, nanotechnology and nanoscience. Dr. Cherry Bhargava is an Associate Professor and Head, VLSI domain, at the School of Electrical and Electronics Engineering of Lovely Professional University, Jalandhar, India. Dr. Amit Sachdeva is an Associate Professor at Lovely Professional University, Jalandhar, India.
Publisher: CRC Press
ISBN: 1000197123
Category : Technology & Engineering
Languages : en
Pages : 349
Book Description
Nanotechnology: Advances and Real-Life Applications offers a comprehensive reference text about advanced concepts and applications in the field of nanotechnology. The text – written by researchers practicing in the field – presents a detailed discussion of key concepts including nanomaterials and their synthesis, fabrication and characterization of nanomaterials, carbon-based nanomaterials, nano-bio interface, and nanoelectronics. The applications of nanotechnology in the fields of renewable energy, medicine and agriculture are each covered in a dedicated chapter. The text will be invaluable for senior undergraduate and graduate students in the fields of electrical engineering, electronics engineering, nanotechnology and nanoscience. Dr. Cherry Bhargava is an Associate Professor and Head, VLSI domain, at the School of Electrical and Electronics Engineering of Lovely Professional University, Jalandhar, India. Dr. Amit Sachdeva is an Associate Professor at Lovely Professional University, Jalandhar, India.
Nanotechnology and the Challenges of Equity, Equality and Development
Author: Susan E. Cozzens
Publisher: Springer Science & Business Media
ISBN: 9048196159
Category : Social Science
Languages : en
Pages : 471
Book Description
Nanotechnology is enabling applications in materials, microelectronics, health, and agriculture, which are projected to create the next big shift in production, comparable to the industrial revolution. Such major shifts always co-evolve with social relationships. This book focuses on how nanotechnologies might affect equity/equality in global society. Nanotechnologies are likely to open gaps by gender, ethnicity, race, and ability status, as well as between developed and developing countries, unless steps are taken now to create a different outcome. Organizations need to change their practices, and cultural ideas must be broadened if currently disadvantaged groups are to have a more equal position in nano-society rather than a more disadvantaged one. Economic structures are likely to shift in the nano-revolution, requiring policymakers and participatory processes to invent new institutions for social welfare, better suited to the new economic order than those of the past.
Publisher: Springer Science & Business Media
ISBN: 9048196159
Category : Social Science
Languages : en
Pages : 471
Book Description
Nanotechnology is enabling applications in materials, microelectronics, health, and agriculture, which are projected to create the next big shift in production, comparable to the industrial revolution. Such major shifts always co-evolve with social relationships. This book focuses on how nanotechnologies might affect equity/equality in global society. Nanotechnologies are likely to open gaps by gender, ethnicity, race, and ability status, as well as between developed and developing countries, unless steps are taken now to create a different outcome. Organizations need to change their practices, and cultural ideas must be broadened if currently disadvantaged groups are to have a more equal position in nano-society rather than a more disadvantaged one. Economic structures are likely to shift in the nano-revolution, requiring policymakers and participatory processes to invent new institutions for social welfare, better suited to the new economic order than those of the past.
Smart Nanomaterials to Combat the Spread of Viral Infections
Author: Raju Khan
Publisher: Elsevier
ISBN: 0323993796
Category : Science
Languages : en
Pages : 449
Book Description
Smart Nanomaterials to Combat the Spread of Viral Infections comprises nanotechnology-based approaches with detailed preventive and treatment methodology for enabling their application in antiviral systems. This book discusses the role of metal nanoparticles in the treatment of and prevention of viral infections and nanotechnology advancements in antiviral coatings to combat affected surfaces. It also covers the use of nanomaterials for the efficient intracellular delivery of antiviral agents to disinfect and treat viral infections. This is a timely coverage of how nanotechnologies and materials as well as the utilization of artificial intelligence and Internet of things–based smart nano-systems are used to control and manage viral infections during the COVID-19 pandemic. Advances in smart research and future antimicrobial applications round out the book. This book provides a comprehensive overview of smart nanomaterials and advanced nano-system applications to researchers and academics in virology, microbiology, chemistry, material science, nanotechnology, and biotechnology as well as those in industries interested in their virucidal properties to prevent viral infections. - Encompasses the novel synthesis of nanostructures and cost-effective nanosystems from functional hybrid materials with special emphasis on their effective virucidal properties being biocompatible and economic - Examines mechanisms of advanced nanomaterials as effective virucidal agents in disinfectants, coatings, treatment, and preventive approaches - Discusses possible advancements and upcoming smart research in antimicrobial applications - Offers timely coverage of SARS-CoV-2 pandemic management strategies
Publisher: Elsevier
ISBN: 0323993796
Category : Science
Languages : en
Pages : 449
Book Description
Smart Nanomaterials to Combat the Spread of Viral Infections comprises nanotechnology-based approaches with detailed preventive and treatment methodology for enabling their application in antiviral systems. This book discusses the role of metal nanoparticles in the treatment of and prevention of viral infections and nanotechnology advancements in antiviral coatings to combat affected surfaces. It also covers the use of nanomaterials for the efficient intracellular delivery of antiviral agents to disinfect and treat viral infections. This is a timely coverage of how nanotechnologies and materials as well as the utilization of artificial intelligence and Internet of things–based smart nano-systems are used to control and manage viral infections during the COVID-19 pandemic. Advances in smart research and future antimicrobial applications round out the book. This book provides a comprehensive overview of smart nanomaterials and advanced nano-system applications to researchers and academics in virology, microbiology, chemistry, material science, nanotechnology, and biotechnology as well as those in industries interested in their virucidal properties to prevent viral infections. - Encompasses the novel synthesis of nanostructures and cost-effective nanosystems from functional hybrid materials with special emphasis on their effective virucidal properties being biocompatible and economic - Examines mechanisms of advanced nanomaterials as effective virucidal agents in disinfectants, coatings, treatment, and preventive approaches - Discusses possible advancements and upcoming smart research in antimicrobial applications - Offers timely coverage of SARS-CoV-2 pandemic management strategies
ICSA 2019
Author: Farit Mochamad Afendi
Publisher: European Alliance for Innovation
ISBN: 1631902202
Category : Education
Languages : en
Pages : 610
Book Description
This conference serves as a means of presenting and discussing various research results among academics, researchers, and practitioners in the fields of statistics, analytics, computing, data science, and its application. Based on 110 papers that have been presented there are three main topics as the focus of the discussion, namely Statistical Modeling, Predictive Analytics, and Pattern Learning. The approach is in the form of a study to obtain a valid methodology for extracting, collecting, storing, analyzing, and visualizing data including those derived from big data. The application studies cover various fields such as agriculture, climate, energy, industry, business, social, and so on. The conference is expected to be able to provide solutions to various problems in various fields through statistical and analytical approaches.
Publisher: European Alliance for Innovation
ISBN: 1631902202
Category : Education
Languages : en
Pages : 610
Book Description
This conference serves as a means of presenting and discussing various research results among academics, researchers, and practitioners in the fields of statistics, analytics, computing, data science, and its application. Based on 110 papers that have been presented there are three main topics as the focus of the discussion, namely Statistical Modeling, Predictive Analytics, and Pattern Learning. The approach is in the form of a study to obtain a valid methodology for extracting, collecting, storing, analyzing, and visualizing data including those derived from big data. The application studies cover various fields such as agriculture, climate, energy, industry, business, social, and so on. The conference is expected to be able to provide solutions to various problems in various fields through statistical and analytical approaches.
Nanotechnology
Author: Ahmed S. Khan
Publisher: CRC Press
ISBN: 1439859531
Category : Business & Economics
Languages : en
Pages : 385
Book Description
Advances in nanotechnology are transforming the ways of creating materials and products, leading society to the threshold of a second industrial revolution. However, future opportunities will depend significantly on how nanotechnology stakeholders deal with the short-term and long-term benefits, limitations, uncertainties and risks of nanotechnology. They will be tasked with navigating a variety of new social and ethical challenges associated with areas such as privacy, the environment, energy, population, genetics, agriculture, food, and security. Unique in its depth, breadth, and variety of viewpoints, Nanotechnology: Ethical and Social Implications stimulates, inspires, and builds awareness of nanotechnology’s impact on society. Spanning the immense range of disciplines at work in nanotechnology, the book’s selection of chapters focuses on how advances in science, and the convergence of multiple technologies, will impact society at individual, community, national, and international levels. The book focuses on raising the awareness of nanotechnology stakeholders, which includes undergraduate and graduate students; educators in sciences, engineering, business, and public policy; engineers; business and finance professionals; and policymakers. It also addresses the demands on the future workforce to learn new skill sets. The book uses an interactive format—which includes case studies, scenarios, and Web exercises—to promote critical thinking and problem solving skills. Content includes numerous tables, statistics, and figures to supplement and enhance the topics covered in each chapter. The result is a must-read for anyone seeking either a technical or nontechnical understanding of the societal impact of nanotechnology.
Publisher: CRC Press
ISBN: 1439859531
Category : Business & Economics
Languages : en
Pages : 385
Book Description
Advances in nanotechnology are transforming the ways of creating materials and products, leading society to the threshold of a second industrial revolution. However, future opportunities will depend significantly on how nanotechnology stakeholders deal with the short-term and long-term benefits, limitations, uncertainties and risks of nanotechnology. They will be tasked with navigating a variety of new social and ethical challenges associated with areas such as privacy, the environment, energy, population, genetics, agriculture, food, and security. Unique in its depth, breadth, and variety of viewpoints, Nanotechnology: Ethical and Social Implications stimulates, inspires, and builds awareness of nanotechnology’s impact on society. Spanning the immense range of disciplines at work in nanotechnology, the book’s selection of chapters focuses on how advances in science, and the convergence of multiple technologies, will impact society at individual, community, national, and international levels. The book focuses on raising the awareness of nanotechnology stakeholders, which includes undergraduate and graduate students; educators in sciences, engineering, business, and public policy; engineers; business and finance professionals; and policymakers. It also addresses the demands on the future workforce to learn new skill sets. The book uses an interactive format—which includes case studies, scenarios, and Web exercises—to promote critical thinking and problem solving skills. Content includes numerous tables, statistics, and figures to supplement and enhance the topics covered in each chapter. The result is a must-read for anyone seeking either a technical or nontechnical understanding of the societal impact of nanotechnology.
Nanotechnology and Microelectronics: Global Diffusion, Economics and Policy
Author: Ekekwe, Ndubuisi
Publisher: IGI Global
ISBN: 1616920076
Category : Technology & Engineering
Languages : en
Pages : 538
Book Description
"This book assesses the state of nanotechnology and microelectronics, and examines many issues, such as climate change, trade, innovation, diffusion, etc, with a theme focused on facilitating the structures for the adoption and penetration of the technologies into developing nations"--Provided by publisher.
Publisher: IGI Global
ISBN: 1616920076
Category : Technology & Engineering
Languages : en
Pages : 538
Book Description
"This book assesses the state of nanotechnology and microelectronics, and examines many issues, such as climate change, trade, innovation, diffusion, etc, with a theme focused on facilitating the structures for the adoption and penetration of the technologies into developing nations"--Provided by publisher.
Nanotechnology in Societal Development
Author: Soney C. George
Publisher: Springer Nature
ISBN: 9819761840
Category :
Languages : en
Pages : 552
Book Description
Publisher: Springer Nature
ISBN: 9819761840
Category :
Languages : en
Pages : 552
Book Description
Nanotechnology Research Directions: IWGN Workshop Report
Author: R.S. Williams
Publisher: Springer Science & Business Media
ISBN: 9401595763
Category : Technology & Engineering
Languages : en
Pages : 367
Book Description
energy production, environmental management, transportation, communication, computation, and education. As the twenty-first century unfolds, nanotechnology's impact on the health, wealth, and security of the world's people is expected to be at least as significant as the combined influences in this century of antibiotics, the integrated circuit, and human-made polymers. Dr. Neal Lane, Advisor to the President for Science and Technology and former National Science Foundation (NSF) director, stated at a Congressional hearing in April 1998, "If I were asked for an area of science and engineering that will most likely produce the breakthroughs of tomorrow, I would point to nanoscale science and engineering. " Recognizing this potential, the White House Office of Science and Technology Policy (OSTP) and the Office of Management and Budget (OMB) have issued a joint memorandum to Federal agency heads that identifies nanotechnology as a research priority area for Federal investment in fiscal year 2001. This report charts "Nanotechnology Research Directions," as developed by the Interagency W orking Group on Nano Science, Engineering, and Technology (IWGN) of the National Science and Technology Council (NSTC). The report incorporates the views of leading experts from government, academia, and the private sector. It reflects the consensus reached at an IWGN-sponsored workshop held on January 27-29, 1999, and detailed in contributions submitted thereafter by members of the V. S. science and engineering community. (See Appendix A for a list of contributors.
Publisher: Springer Science & Business Media
ISBN: 9401595763
Category : Technology & Engineering
Languages : en
Pages : 367
Book Description
energy production, environmental management, transportation, communication, computation, and education. As the twenty-first century unfolds, nanotechnology's impact on the health, wealth, and security of the world's people is expected to be at least as significant as the combined influences in this century of antibiotics, the integrated circuit, and human-made polymers. Dr. Neal Lane, Advisor to the President for Science and Technology and former National Science Foundation (NSF) director, stated at a Congressional hearing in April 1998, "If I were asked for an area of science and engineering that will most likely produce the breakthroughs of tomorrow, I would point to nanoscale science and engineering. " Recognizing this potential, the White House Office of Science and Technology Policy (OSTP) and the Office of Management and Budget (OMB) have issued a joint memorandum to Federal agency heads that identifies nanotechnology as a research priority area for Federal investment in fiscal year 2001. This report charts "Nanotechnology Research Directions," as developed by the Interagency W orking Group on Nano Science, Engineering, and Technology (IWGN) of the National Science and Technology Council (NSTC). The report incorporates the views of leading experts from government, academia, and the private sector. It reflects the consensus reached at an IWGN-sponsored workshop held on January 27-29, 1999, and detailed in contributions submitted thereafter by members of the V. S. science and engineering community. (See Appendix A for a list of contributors.