Systems biology is the computational and mathematical modeling of complex biological systems. It is a biology-based interdisciplinary field of study that focuses on complex interactions within biological systems, using a holistic approach to biological research. From year 2000 onwards, the concept has been used in biology in a variety of contexts; the Human Genome Project is an example of applied systems thinking in biology which has led to new, collaborative ways of working on problems in the biological field of genetics. One of the aims of systems biology is to model and discover emergent properties, properties of cells and organisms functioning as a system whose theoretical description is only possible using techniques of systems biology; these involve metabolic networks or cell signaling networks. Systems biology can be considered from a number of different aspects; as a field of study the study of the interactions between the components of biological systems, how these interactions give rise to the function and behavior of that system.
As a paradigm defined in antithesis to the so-called reductionist paradigm, although consistent with the scientific method. The distinction between the two paradigms is referred to in these quotations: "The reductionist approach has identified most of the components and many of the interactions but offers no convincing concepts or methods to understand how system properties emerge... the pluralism of causes and effects in biological networks is better addressed by observing, through quantitative measures, multiple components and by rigorous data integration with mathematical models." "Systems biology... is about putting together rather than taking apart, integration rather than reduction. It requires that we develop ways of thinking about integration that are as rigorous as our reductionist programmes, but different.... It means changing our philosophy, in the full sense of the term." As a series of operational protocols used for performing research, namely a cycle composed of theory, analytic or computational modelling to propose specific testable hypotheses about a biological system, experimental validation, using the newly acquired quantitative description of cells or cell processes to refine the computational model or theory.
Since the objective is a model of the interactions in a system, the experimental techniques that most suit systems biology are those that are system-wide and attempt to be as complete as possible. Therefore, metabolomics and high-throughput techniques are used to collect quantitative data for the construction and validation of models; as the application of dynamical systems theory to molecular biology. Indeed, the focus on the dynamics of the studied systems is the main conceptual difference between systems biology and bioinformatics; as a socioscientific phenomenon defined by the strategy of pursuing integration of complex data about the interactions in biological systems from diverse experimental sources using interdisciplinary tools and personnel. This variety of viewpoints is illustrative of the fact that systems biology refers to a cluster of peripherally overlapping concepts rather than a single well-delineated field. However, the term has widespread currency and popularity as of 2007, with chairs and institutes of systems biology proliferating worldwide.
Systems biology finds its roots in the quantitative modeling of enzyme kinetics, a discipline that flourished between 1900 and 1970, the mathematical modeling of population dynamics, the simulations developed to study neurophysiology, control theory and cybernetics, synergetics. One of the theorists who can be seen as one of the precursors of systems biology is Ludwig von Bertalanffy with his general systems theory. One of the first numerical simulations in cell biology was published in 1952 by the British neurophysiologists and Nobel prize winners Alan Lloyd Hodgkin and Andrew Fielding Huxley, who constructed a mathematical model that explained the action potential propagating along the axon of a neuronal cell, their model described a cellular function emerging from the interaction between two different molecular components, a potassium and a sodium channel, can therefore be seen as the beginning of computational systems biology. In 1952, Alan Turing published The Chemical Basis of Morphogenesis, describing how non-uniformity could arise in an homogeneous biological system.
In 1960, Denis Noble developed the first computer model of the heart pacemaker. The formal study of systems biology, as a distinct discipline, was launched by systems theorist Mihajlo Mesarovic in 1966 with an international symposium at the Case Institute of Technology in Cleveland, titled "Systems Theory and Biology"; the 1960s and 1970s saw the development of several approaches to study complex molecular systems, such as the metabolic control analysis and the biochemical systems theory. The successes of molecular biology throughout the 1980s, coupled with a skepticism toward theoretical biology, that promised more than it achieved, caused the quantitative modeling of biological processes to become a somewhat minor field. However, the birth of functional genomics in the 1990s meant that large quantities of high-quality data became available, while the computing power exploded, making more realistic models possible. In 1992 1994, serial articles on systems medicine, systems genetics, systems biological engineering by B. J. Zeng was published in China and was giving a lecture on biosystems theory and systems-approach r
Peking University is a major research university in Beijing, a member of the elite C9 League of Chinese universities. The first modern national university established in China, it was founded during the late Qing Dynasty in 1898 as the Imperial University of Peking and was the successor of the Guozijian, or Imperial College; the university's English name retains the older transliteration of "Beijing", superseded in most other contexts. Throughout its history, Peking University has played an important role "at the center of major intellectual movements" in China. Starting from the early 1920s, the university became a center for China's emerging progressive movements. Faculty and students held important roles in originating the New Culture Movement, the May Fourth Movement protests, other significant cultural and sociopolitical events, to the extent that the university's history has been tied to that of modern China. Peking University has educated and hosted many prominent modern Chinese figures, including Mao Zedong, Lu Xun, Gu Hongming, Hu Shi, Mao Dun, Li Dazhao, Chen Duxiu, the current Premier Li Keqiang.
As of 2018, Peking University is ranked as one of the two top academic institutions in China, along with nearby Tsinghua University. It is among the most selective universities for undergraduate admissions in China and hosts one of the only undergraduate liberal arts colleges in Asia, it is a Class A institution under the national Double First Class University program. Peking University's faculty includes 76 members of the Chinese Academy of Sciences, 19 members of the Chinese Academy of Engineering, 25 members of the World Academy of Sciences. Peking University Library is one of the largest libraries in the world with over 8 million volumes; the university operates the PKU Hall, a professional performing arts centers, the Arthur M. Sackler Museum of Arts and Archaeology. Peking University's affiliated Founder Corporation is the largest university-affiliated company in China, with total assets valued at 239.3 billion renminbi as of 2016. Peking University is renowned for its campus grounds and the beauty of its traditional Chinese architecture.
From its establishment on July 3, 1898, the school was known as the Imperial University of Peking. The school was established to replace the Taixue the Guozijian, or Imperial College, as part of the Hundred Days' Reform initiated by Emperor Guangxu. Liang Qichao drafted the University's organising regulations; the university was authorised to supervise all provincial schools. Sun Jianai, who served as the minister of the Ministry of Personnel under the Qing court, was appointed to manage the university. Recommended by Li Hongzhang, Emperor Guangxu appointed American missionary William Alexander Parson Martin to serve as the dean of Department of Western Learning. Emperor Guangxu's reform initiatives were intensely opposed by powerful conservatives of the Qing court. On Sep 21,1898, Empress Dowager Cixi, with support from conservatives, abruptly ended the Hundred Days' Reform and put Guangxu under house arrest at the Summer Palace. Cixi's coup d'état was followed by immediate rescinding of all policies and laws enacted by Guangxu and his reform-minded supporters, the Imperial University of Peking was the only part of the reform that survived.
In 1900, the university was paralyzed by the Boxer Rebellion in the year, the "Eight-Power Allied Forces" （八国联军）entered Beijing and the university's operating was continually suspended. In 1902, "Jingshitongwenguan", a school established by the Qing court in 1862 for foreign language learning was incorporated into the Imperial University of Peking. In 1904, the university sent 47 students to study abroad, which marked the first time for Chinese higher education institution to send students to foreign countries. Following the Xinhai Revolution, the Imperial University of Peking was renamed "Government University of Peking" in 1912 and "National University of Peking" in 1919; the noted scholar Cai Yuanpei was appointed president on January 4, 1917, helped transform Peking University into the country's largest institution of higher learning, with 14 departments and an enrollment of more than 2,000 students. President Cai, inspired by the German model of academic freedom, introduced faculty governance and democratic management to the university.
Cai recruited an intellectually diverse faculty that included some of the most prominent figures in the progressive New Culture Movement, including Hu Shih, Liu Banlong, Ma Yinchu, Li Dazhao, Chen Duxiu, Lu Xun and Liang Shuming. Meanwhile, leading conservatives Gu Hongming and Huang Kan taught at the university. A firm supporter for freedom of thought, Cai advocated for educational independence and resigned several times protesting the government's policy and interference. On May 1, 1919, some students of Peking University learned that the Treaty of Versailles would allow Japan to receive Germany's colonising rights in Shandong province. An assembly at Peking University that included these students and representatives from other universities in Beijing was organised. On May 4, students from thirteen universities marched to Tiananmen to protest the terms of Treaty of Versailles, demanded the Beiyang government to refuse to sign the treaty. Demonstrators demanded the immediate resignation of three officials: Cao Rulin, Minister of the Ministry of Transportation, Zhang Zongxiang, China's Ambassador to Japan and Lu Zongyu, Minister of Currency, who they believed were in cooperation with Japanese.
The protest ended up
Leo Philip Kadanoff was an American physicist. He was a professor of physics at the University of Chicago and a former President of the American Physical Society, he contributed to the fields of statistical physics, chaos theory, theoretical condensed matter physics. Kadanoff was raised in New York City, he received his undergraduate doctorate in physics from Harvard University. After a post-doctorate at the Niels Bohr Institute in Copenhagen, he joined the physics faculty at the University of Illinois in 1965. Kadanoff's early research focused upon superconductivity. In the late 1960s, he studied the organization of matter in phase transitions. Kadanoff demonstrated that sudden changes in material properties could be understood in terms of scaling and universality. With his collaborators, he showed how all the experimental data available for the changes, called second-order phase transitions, could be understood in terms of these two ideas; these same ideas have now been extended to apply to a broad range of scientific and engineering problems, have found numerous and important applications in urban planning, computer science, biology, applied mathematics and geophysics.
In recognition of these achievements, he won the Buckley Prize of the American Physical Society, the Wolf Prize in Physics, the 1989 Boltzmann Medal of the International Union of Pure and Applied Physics, the 2006 Lorentz Medal. In 1969 he moved to Brown University, he exploited mathematical analogies between solid state physics and urban growth to shed insights into the latter field, so much so that he contributed to the statewide planning program in Rhode Island. In 1978 he moved to the University of Chicago, where he became the John D. and Catherine T. MacArthur Distinguished Service Professor of Physics and Mathematics. Much of his work in the second half of his career involved contributions to chaos theory, in both mechanical and fluid systems, he was elected a Fellow of the American Academy of Arts and Sciences in 1982. He was one of the recipients of the 1999 National Medal of Science, awarded by President Clinton, he is a member of the National Academy of Sciences and of the American Philosophical Society as well as being a Fellow of the American Physical Society and of the American Association for the Advancement of Science.
During the last decade, he has received the Quantrell Award from the University of Chicago, the Centennial Medal of Harvard University, the Lars Onsager Prize of the American Physical Society, the Grande Medaille d'Or of the Académie des sciences de l'Institut de France. His textbook with Gordon Baym, Quantum Statistical Mechanics, is a prominent text in the field and has been translated. With Leo Irakliotis, Kadanoff established the Center for Presentation of Science at the University of Chicago. In June 2013, it was stated that anonymous donors had provided a $3.5 million gift to establish the Leo Kadanoff Center for Theoretical Physics at the University of Chicago. He died after complications from an illness on October 26, 2015. "Scaling laws for Ising models near T c ", Physics 2, 1966. "Operator Algebra and the Determination of Critical Indices", Phys. Rev. Lett. 23, 1969. "Leo P. Kadanoff" at the University of Chicago "Publications of Leo P. Kadanoff" Video of Leo Kadanoff on the opening panel at the Quantum to Cosmos festival
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois. Founded in 1890 by John D. Rockefeller, the school is located on a 217-acre campus in Chicago's Hyde Park neighborhood, near Lake Michigan; the University of Chicago holds top-ten positions in various international rankings. The university is composed of an undergraduate college as well as various graduate programs and interdisciplinary committees organized into five academic research divisions. Beyond the arts and sciences, Chicago is well known for its professional schools, which include the Pritzker School of Medicine, the Booth School of Business, the Law School, the School of Social Service Administration, the Harris School of Public Policy Studies, the Divinity School and the Graham School of Continuing Liberal and Professional Studies; the university has additional campuses and centers in London, Beijing and Hong Kong, as well as in downtown Chicago. University of Chicago scholars have played a major role in the development of many academic disciplines, including sociology, economics, literary criticism and the behavioralism school of political science.
Chicago's physics department and the Met Lab helped develop the world's first man-made, self-sustaining nuclear reaction beneath the viewing stands of university's Stagg Field, a key part of the classified Manhattan Project effort of World War II. The university research efforts include administration of Fermi National Accelerator Laboratory and Argonne National Laboratory, as well as the Marine Biological Laboratory; the university is home to the University of Chicago Press, the largest university press in the United States. With an estimated completion date of 2021, the Barack Obama Presidential Center will be housed at the university and include both the Obama presidential library and offices of the Obama Foundation; the University of Chicago has produced faculty members and researchers. As of 2018, 98 Nobel laureates have been affiliated with the university as professors, faculty, or staff, making it a university with one of the highest concentrations of Nobel laureates in the world. 34 faculty members and 18 alumni have been awarded the MacArthur "Genius Grant".
In addition, Chicago's alumni and faculty include 54 Rhodes Scholars, 26 Marshall Scholars, 9 Fields Medalists, 4 Turing Award Winners, 24 Pulitzer Prize winners, 20 National Humanities Medalists, 16 billionaire graduates and a plethora of members of the United States Congress and heads of state of countries all over the world. The University of Chicago was incorporated as a coeducational institution in 1890 by the American Baptist Education Society, using $400,000 donated to the ABES to match a $600,000 donation from Baptist oil magnate and philanthropist John D. Rockefeller, including land donated by Marshall Field. While the Rockefeller donation provided money for academic operations and long-term endowment, it was stipulated that such money could not be used for buildings; the Hyde Park campus was financed by donations from wealthy Chicagoans like Silas B. Cobb who provided the funds for the campus' first building, Cobb Lecture Hall, matched Marshall Field's pledge of $100,000. Other early benefactors included businessmen Charles L. Hutchinson, Martin A. Ryerson Adolphus Clay Bartlett and Leon Mandel, who funded the construction of the gymnasium and assembly hall, George C. Walker of the Walker Museum, a relative of Cobb who encouraged his inaugural donation for facilities.
The Hyde Park campus continued the legacy of the original university of the same name, which had closed in 1880s after its campus was foreclosed on. What became known as the Old University of Chicago had been founded by a small group of Baptist educators in 1856 through a land endowment from Senator Stephen A. Douglas. After a fire, it closed in 1886. Alumni from the Old University of Chicago are recognized as alumni of the present University of Chicago; the university's depiction on its coat of arms of a phoenix rising from the ashes is a reference to the fire and demolition of the Old University of Chicago campus. As an homage to this pre-1890 legacy, a single stone from the rubble of the original Douglas Hall on 34th Place was brought to the current Hyde Park location and set into the wall of the Classics Building; these connections have led the Dean of the College and University of Chicago and Professor of History John Boyer to conclude that the University of Chicago has, "a plausible genealogy as a pre–Civil War institution".
William Rainey Harper became the university's president on July 1, 1891 and the Hyde Park campus opened for classes on October 1, 1892. Harper worked on building up the faculty and in two years he had a faculty of 120, including eight former university or college presidents. Harper was an accomplished scholar and a member of the Baptist clergy who believed that a great university should maintain the study of faith as a central focus. To fulfill this commitment, he brought the Old University of Chicago's Seminary to Hyde Park; this became the Divinity School in the first professional school at the University of Chicago. Harper recruited acclaimed Yale baseball and football player Amos Alonzo Stagg from the Young Men's Christian Association training Shool at Springfield to coach the school's football program. Stagg was given a position on the first such athletic position in the United States. While coaching at the University, Stagg invented the numbered football jersey, the huddle, the lighted playing field.
Stagg is the namesake of the university's Stagg
Protein folding is the physical process by which a protein chain acquires its native 3-dimensional structure, a conformation, biologically functional, in an expeditious and reproducible manner. It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil; each protein exists as an unfolded polypeptide or random coil when translated from a sequence of mRNA to a linear chain of amino acids. This polypeptide lacks any stable three-dimensional structure; as the polypeptide chain is being synthesized by a ribosome, the linear chain begins to fold into its three-dimensional structure. Folding begins to occur during translation of the polypeptide chain. Amino acids interact with each other to produce a well-defined three-dimensional structure, the folded protein, known as the native state; the resulting three-dimensional structure is determined by the amino acid sequence or primary structure. The correct three-dimensional structure is essential to function, although some parts of functional proteins may remain unfolded, so that protein dynamics is important.
Failure to fold into native structure produces inactive proteins, but in some instances misfolded proteins have modified or toxic functionality. Several neurodegenerative and other diseases are believed to result from the accumulation of amyloid fibrils formed by misfolded proteins. Many allergies are caused by incorrect folding of some proteins, because the immune system does not produce antibodies for certain protein structures. Denaturation of proteins is a process of transition from the folded to the unfolded state, it happens in cooking, in burns, in proteinopathies, in other contexts. The duration of the folding process varies depending on the protein of interest; when studied outside the cell, the slowest folding proteins require many minutes or hours to fold due to proline isomerization, must pass through a number of intermediate states, like checkpoints, before the process is complete. On the other hand small single-domain proteins with lengths of up to a hundred amino acids fold in a single step.
Time scales of milliseconds are the norm and the fastest known protein folding reactions are complete within a few microseconds. The primary structure of a protein, its linear amino-acid sequence, determines its native conformation; the specific amino acid residues and their position in the polypeptide chain are the determining factors for which portions of the protein fold together and form its three-dimensional conformation. The amino acid composition is not as important as the sequence; the essential fact of folding, remains that the amino acid sequence of each protein contains the information that specifies both the native structure and the pathway to attain that state. This is not to say. Conformations differ based on environmental factors as well. Formation of a secondary structure is the first step in the folding process that a protein takes to assume its native structure. Characteristic of secondary structure are the structures known as alpha helices and beta sheets that fold because they are stabilized by intramolecular hydrogen bonds, as was first characterized by Linus Pauling.
Formation of intramolecular hydrogen bonds provides another important contribution to protein stability. Α-helices are formed by hydrogen bonding of the backbone to form a spiral shape. The β pleated sheet is a structure that forms with the backbone bending over itself to form the hydrogen bonds; the hydrogen bonds are between the amide carbonyl oxygen of the peptide bond. There exists anti-parallel β pleated sheets and parallel β pleated sheets where the stability of the hydrogen bonds is stronger in the anti-parallel β sheet as it hydrogen bonds with the ideal 180 degree angle compared to the slanted hydrogen bonds formed by parallel sheets; the alpha helices and beta pleated sheets can be amphipathic in nature, or contain a hydrophilic portion and a hydrophobic portion. This property of secondary structures aids in the tertiary structure of a protein in which the folding occurs so that the hydrophilic sides are facing the aqueous environment surrounding the protein and the hydrophobic sides are facing the hydrophobic core of the protein.
Secondary structure hierarchically gives way to tertiary structure formation. Once the protein's tertiary structure is formed and stabilized by the hydrophobic interactions, there may be covalent bonding in the form of disulfide bridges formed between two cysteine residues. Tertiary structure of a protein involves a single polypeptide chain. Tertiary structure may give way to the formation of quaternary structure in some proteins, which involves the "assembly" or "coassembly" of subunits that have folded. Folding is a spontaneous process, guided by hydrophobic interactions, formation of intramolecular hydrogen bonds, van der Waals forces, it is opposed by conformational entropy; the process of folding begins co-translationally, so that the N-terminus of the protein begins to fold while the C-terminal portion of the protein is still being synthesized by the ribosome. While these mac
Tsung-Dao Lee is a Chinese-American physicist, known for his work on parity violation, the Lee Model, particle physics, relativistic heavy ion physics, nontopological solitons and soliton stars. He holds the rank of University Professor Emeritus at Columbia University, where he has taught since 1953 and from which he retired in 2012. In 1957, Lee, at the age of 30, won the Nobel Prize in Physics with Franklin C N Yang for their work on the violation of the parity law in weak interactions, which Chien-Shiung Wu experimentally verified in 1956, with her so-called Wu experiment. Lee remains the youngest Nobel laureate in the science fields after World War II, he is the third youngest Nobel laureate in sciences in history after William L. Bragg and Werner Heisenberg. Lee and Yang were the first Chinese laureates. Since he became a naturalized American citizen in 1962, Lee is the youngest American to have won a Nobel Prize. Lee was born in Shanghai, with his ancestral home in nearby Suzhou, his father Chun-kang Lee, one of the first graduates of the University of Nanking, was a chemical industrialist and merchant, involved in China's early development of modern synthesized fertilizer.
Lee's grandfather Chong-tan Lee was the first Chinese Methodist Episcopal senior pastor of St. John's Church in Suzhou. Lee has one sister. Educator Robert C. T. Lee is one of T. D.'s brothers. Lee's mother Chang and brother Robert C. T. moved to Taiwan in the 1950s. They were jailed in Taiwan during the White Terror. Lee received his secondary education in Jiangxi. Due to the Second Sino-Japanese war, Lee's high school education was interrupted, thus he did not obtain his secondary diploma. In 1943, Lee directly applied to and was admitted by the National Che Kiang University. Lee registered as a student in the Department of Chemical Engineering. Lee's talent was discovered and his interest in physics grew rapidly. Several physics professors, including Shu Xingbei and Wang Ganchang guided Lee, he soon transferred into the Department of Physics of National Che Kiang University, where he studied in 1943–1944. However, again disrupted by a further Japanese invasion, Lee continued at the National Southwestern Associated University in Kunming the next year in 1945, where he studied with Professor Wu Ta-You.
Professor Wu nominated Lee for a Chinese government fellowship for graduate study in US. In 1946, Lee went to the University of Chicago and was selected by Professor Enrico Fermi to become his PhD student. Lee received PhD under Fermi in 1950 for his research work Hydrogen Content of White Dwarf Stars. Lee served as research associate and lecturer in physics at the University of California at Berkeley from 1950 to 1951. In 1953, Lee joined Columbia University, his first work at Columbia was on a solvable model of quantum field theory better known as the Lee Model. Soon, his focus turned to the developing puzzle of K meson decays. Lee realized in early 1956. At Lee's suggestion, the first experimental test was on hyperion decay by the Steinberger group. At that time, the experimental result gave only an indication of a 2 standard deviation effect of possible parity violation. Encouraged by this feasibility study, Lee made a systematic study of possible P,T,C and CP violations in weak interactions with collaborators, including C. N. Yang.
After the definitive experimental confirmation by C. S. Wu and her collaborators of parity non-conservation and Yang were awarded the 1957 Nobel Prize for Physics. In the early 1960s, Lee and collaborators initiated the important field of high energy neutrino physics. In 1964, with M. Nauenberg, analyzed the divergences connected with particles of zero rest mass, described a general method known as the KLN theorem for dealing with these divergences, which still plays an important role in contemporary work in QCD, with its massless, self-interacting gluons. In 1974–75, Lee published several papers on "A New Form of Matter in High Density", which led to the modern field of RHIC physics, now dominating the entire high energy nuclear physics field. Besides particle physics, Lee has been active in statistical mechanics, hydrodynamics, many body system, solid state, lattice QCD. In 1983, Lee wrote a paper entitled, "Can Time Be a Discrete Dynamical Variable?". Beginning in 1975, Lee and collaborators established the field of non-topological solitons, which led to his work on soliton stars and black holes throughout the 1980s and 1990s.
From 1997 to 2003 Lee was director of the RIKEN-BNL Research Center, which together with other researchers from Columbia, completed a 1 teraflops supercomputer QCDSP for lattice QCD in 1998 and a 10 teraflops QCDOC machine in 2001. Most Lee and Richard M. Friedberg have developed a new method to solve the Schrödinger Equation, leading to convergent iterative solutions for the long-standing quantum degenerate double-wall potential and other instanton problems, they have done work on the neutrino mapping matrix. Soon after the re-establishment of China-American relations with the PRC, Lee and his wife, Jeanne