| 2001 Nobel
Prize in Chemistry. The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry for 2001 for the development of catalytic asymmetric synthesis, with one half jointly to William S. Knowles St Louis, Missouri, USA, and Ryoji Noyori Nagoya University, Chikusa, Nagoya, Japan, "for their work on chirally catalysed hydrogenation reactions" and the other half to K. Barry Sharpless the Scripps Research Institute, La Jolla, California, "for his work on chirally catalysed oxidation reactions". Mirror Image Catalysis Many molecules appear in two forms that mirror each other – just as our hands mirror each other. Such molecules are called chiral. In nature one of these forms is often dominant, so in our cells one of these mirror images of a molecule fits "like a glove", in contrast to the other one which may even be harmful. Pharmaceutical products often consist of chiral molecules, and the difference between the two forms can be a matter of life and death – as was the case, for example, in the thalidomide disaster in the 1960s. That is why it is vital to be able to produce the two chiral forms separately. The year 2001 Nobel Laureates in Chemistry have developed molecules that can catalyse important reactions so that only one of the two mirror image forms is produced. The catalyst molecule, which itself is chiral, speeds up the reaction without being consumed. Just one of these molecules can produce millions of molecules of the desired mirror image form. William S. Knowles discovered that it was possible to use transition metals to make chiral catalysts for an important type of reaction called hydrogenation, thereby obtaining the desired mirror image form as the final product. His research quickly led to an industrial process for the production of the L-DOPA drug which is used in the treatment of Parkinson's disease. Ryoji Noyori has led the further development of this process to today's general chiral catalysts for hydrogenation. K. Barry Sharpless, on the other hand, is awarded half of the Prize for developing chiral catalysts for another important type of reaction – oxidation. The Laureates have opened up a completely new field of research in which it is possible to synthesise molecules and material with new properties. Today the results of their basic research are being used in a number of industrial syntheses of pharmaceutical products such as antibiotics, anti-inflammatory drugs and heart medicines. William S. Knowles, 84, born 1917 (US citizen). PhD 1942 at Columbia University. Previously at Monsanto Company, St Louis, USA. Retired since 1986. Ryoji Noyori, 63 years, born 1938 Kobe, Japan (Japanese citizen). PhD 1967 at Kyoto University. Since 1972 Professor of Chemistry at Nagoya University and since 2000 Director of the Research Center for Materials Science, Nagoya University, Nagoya, Japan. http://www-noyori.os.chem.nagoya-u.ac.jp K. Barry Sharpless, 60 years, born 1941 Philadelphia, Pennsylvania, USA (US citizen). PhD 1968 at Stanford University. Since 1990 W.M. Keck Professor of Chemistry at the Scripps Research Institute, La Jolla, USA. http://www.scripps.edu/chem/sharpless/kbs.html Prize amount: SEK 10 million. Knowles and Noyori share one half and Sharpless receives the other half. |
| Three scientists share the year 2001 Nobel Prize in Chemistry: William S. Knowles, previously at Monsanto Company, St. Louis, Missouri, USA; Ryoji Noyori, Nagoya University, Chikusa, Nagoya, Japan and K. Barry Sharpless, The Scripps Research Institute, La Jolla, California, USA. The Royal Swedish Academy of Sciences has awarded the Prize for their development of catalytic asymmetric synthesis. The achievements of these three chemists are of great importance for academic research, for the development of new drugs and materials, and are being used in many industrial syntheses of pharmaceutical products and other biologically active substances. This is a description and background information about the scientists' award-winning discoveries. Mirror Image Catalysis Chiral molecules
This year's Nobel Prize in Chemistry concerns the way in which certain chiral molecules can be used to speed up and control important chemical reactions. The word chiral comes from the Greek word cheir, which means hand. Our hands are chiral – our right hand is a mirror image of our left hand – as are most of life's molecules. If, for example, we study the common amino acid alanine (figure 1), we see that it can occur in two forms: (S)-alanine and (R)-alanine, which are mirror images. However we twist or turn these forms, we cannot get them to overlap each other. Apparently, they do not have the same three-dimensional structure. The reason is that the carbon atom in the centre binds the four different groups H, CH3, NH2 and COOH, which are located at the corners of a tetrahedron. The unbroken bonds to NH2 and COOH indicate that these bonds are in the plane of the paper, whereas the black wedge shaped bond and the broken wedge shaped bond show that they are directed upwards and downwards respectively in relation to the plane of the paper. It was the Dutch chemist J. H. van 't Hoff and the French chemist J. A. Le Bel who, independently of each other in 1874, discovered this tetrahedral arrangement of the groups around the central carbon atom. (van 't Hoff received the first Nobel Prize in Chemistry 1901, but for other discoveries.) Thus the amino acid alanine occurs in two forms, called enantiomers. When alanine is produced in a laboratory under normal conditions, a mixture is obtained, half of which is (S)-alanine and the other (R)-alanine. The synthesis is symmetrical in the sense that it produces equal amounts of both enantiomers. Asymmetric synthesis, on the other hand, deals with the production of an excess of one of the forms. Why is this so important? Let us go back to nature to find the answer. Nature is chiral One may well think that both forms of chiral molecules ought to be equally common in nature, the reactions should be symmetrical. But when we study the molecules of the cells in close-up, it is evident that nature mainly uses one of the two enantiomers. That is why we have – and this applies to all living material, both vegetable and animal – amino acids, and therefore peptides, enzymes and other proteins, only of one of the mirror image forms. Carbohydrates and nucleic acids like DNA and RNA are other examples. Thus the enzymes in our cells are chiral, as are other receptors that play an important part in cell machinery. This means that they prefer to bind to one of the enantiomers. In other words, the receptors are extremely selective; only one of the enantiomers fits the receptor's site like a key that fits a lock. (This metaphor comes from another Nobel Laureate in Chemistry, Emil Fischer, who was awarded the Prize in 1902.) Since the two enantiomers of a chiral molecule often have totally different effects on cells, it is important to be able to produce each of the two forms pure. Drugs and the smell of lemons
Most drugs consist of chiral molecules. And since a drug must match the molecules it should bind to itself in the cells, it is often only one of the enantiomers that is of interest. In certain cases the other form may even be harmful. This was the case, for example, with the drug thalidomide, which was sold in the 1960s to pregnant women. One of the enantiomers of thalidomide helped against nausea, while the other one could cause foetal damage. There are other, less dramatic examples of how differently the two enantiomers can affect our cells. Limonene, for example, is chiral, but the two enantiomers can be difficult to distinguish at first glance (figure 2). The receptors in our nose are more sensitive. One form certainly smells of lemons but the other of oranges. Catalytic asymmetric synthesis - What is it? It is very important for industry to be able to produce products as pure as possible. It is also important to be able to manufacture large quantities of a product. For this reason the use of catalysts is very important. A catalyst is a substance that increases the rate of the reaction without being consumed itself. During the past few decades there has been intensive research into developing methods for producing - synthesising - one of the enantiomers rather than the other. In a synthesis starting molecules (substrate molecules) are used to build new molecules (products) by means of various chemical reactions. It is to researchers in this field that this year's Nobel Prize in Chemistry has been awarded. The Laureates have developed chiral catalysts for two important classes of reactions in organic chemistry: hydrogenations and oxidations. Knowles' pioneer work In the early sixties it was not known whether catalytic asymmetric hydrogenation was feasible, i.e. would it be possible to catalyse an asymmetric reaction to produce an excess of one of the enantiomers? The breakthrough came in 1968 when William S. Knowles was working at the Monsanto Company, St Louis, USA. He discovered that it was possible to use a transition metal to produce a chiral catalyst that could transfer chirality to a non-chiral substrate and get a chiral product. The reaction was a hydrogenation in which the hydrogen atoms in H2 are added to the carbons in a double bond. A single catalyst molecule can produce millions of molecules of the desired enantiomer.
Knowles' experiments were based on two discoveries that had been made a few years previously. In 1966 Osborn and Wilkinson had published their pioneering synthesis of a soluble transition metal complex, (A in figure 3), that made it possible to catalyse a hydrogenation in solution. Their metal complex was not chiral. At the centre of the complex was the transition metal rhodium which bound four groups, ligands: three triphenylphosphine molecules and one chlorine. The second discovery on which Knowles' pioneering work is based on, is Horner's and Mislow's syntheses of chiral phosphines, for example the enantiomer B shown in figure 3. Knowles' hypothesis was that it might be possible to produce a catalyst for asymmetric hydrogenation if the triphenylphosphine groups in Osborn and Wilkinson's metal complex (A) was replaced by one of the enantiomers of a chiral phosphine.
The phosphine first used by Knowles was not enantiomerally pure, yet it produced a mixture in which there was 15% more of one enantiomer than the other. In other words the enantiomeric excess was 15%. Although this excess was modest and hardly of any practical use, the result proved that it was in fact possible to achieve catalytic asymmetric hydrogenation. Other scientists (Horner, Kagan, Morrison and Bosnich) reached similar results shortly afterwards and they have all contributed to open the door to a new, exciting and important field for both academic and industrial research.
Knowles' aim was to develop an industrial synthesis of the amino acid L-DOPA, which had proved useful in the treatment of Parkinson's disease – a discovery for which A. Carlsson was awarded last year's Nobel Prize in Physiology or Medicine. By testing enantiomers of phosphines with a varied structure Knowles and his colleagues quickly succeeded in producing usable catalysts that provided a high enantiomeric excess, that is, principally L-DOPA. The ligand later used in Monsanto's industrial synthesis of L-DOPA was the diphosphine ligand DiPAMP. A rhodium complex with this ligand (figure 4) gave a mixture of the enantiomers of DOPA in 100% yield. The product contained of 97.5% L-DOPA. Thus Knowles had in a short time succeeded in applying his own basic research and that of others to create an industrial synthesis of a drug. This was the first catalytic asymmetric synthesis. It has been succeeded by many others. How does a chiral catalyst molecule work?
What part does the catalyst molecule itself actually play in asymmetric hydrogenation? Studies by the inorganic chemist J. Halpern and others have clarified the reaction mechanism. The transition metal, rhodium for example, in figure 4, which binds the chiral diphosphine, has the ability to simultaneously bind both H2 and the substrate. The complex obtained then reacts and H2 is added to the double bond in the substrate. This is the vital hydrogenation stage, when a new chiral complex is formed from which the chiral product is released. Thus from a substrate that is not chiral, chirality has been transferred from the chiral catalyst to the product. This product contains more of one enantiomer than of the other, that is, the synthesis is asymmetric. The reason for the enantiomeric excess is to be found in the hydrogenation stage, as the hydrogen can be added in two ways that give the different enantiomers at different rates. These two pathways utilise different transition complexes, which are not mirror images and therefore have different energy. Hydrogenation takes place more rapidly via the complex with the lowest energy, thus producing an excess of one of the enantiomers. This can be compared with the hands in a handshake (figure 5). The hands in a handshake between two right hands match better than a handshake between a right and a left hand. In the development of better asymmetric hydrogenation catalysts it is important to increase the energy difference between the transition complexes in order to obtain, as a consequence, larger enantiomeric excess. This is of vital interest in industrial applications in which the aim is to achieve economy in the process and environmentally acceptable methods, that is, as few waste products as possible. This development has been led by another of this year's Laureates in chemistry, Ryoji Noyori. Noyori’s general hydrogenation catalysts The Japanese scientist Ryoji Noyori has carried out extensive and intensive research and developed better and more general catalysts for hydrogenation. The consequences of his research are of great importance.
In 1980 Noyori and co-workers published an article on the synthesis of both enantiomers of the diphosphine ligand BINAP (figure 6). These catalyse, in complexes with rhodium, the synthesis of certain amino acids with an enantiomeric excess of up to 100%. The company Takasago International uses BINAP in the industrial synthesis of the chiral aroma substance menthol, since the early 1980s. But Noyori also saw the need for more general catalysts with broader applications. Exchanging rhodium, Rh(I), for another transition metal, ruthenium, Ru(II), proved, for example, to be successful. The ruthenium(II)-BINAP complex hydrogenates many types of molecules with other functional groups. These reactions give a high enantiomeric excess and high yields and can be scaled up for industrial use. Noyori's Ru-BINAP is used as a catalyst in the production of (R)-1,2-propandiol for the industrial synthesis of an antibiotic, levofloxacin. Similar reactions are used for the synthesis of other antibiotics. Figure 6 gives an example of a stereoselective ketone reduction. Noyori's catalysts have found wide application in the synthesis of fine chemicals, pharmaceutical products and new, advanced materials.
Alongside the advances in chirally catalysed hydrogenation reactions, Barry Sharpless has developed corresponding chiral catalysts for other important reactions, oxidations. While hydrogenation removes a functional group because the double bond is saturated, oxidation leads to increased functionality. This creates new possibilities for building new complex molecules. Sharpless realised that there was a great need for catalysts for asymmetric oxidations. He also had ideas as to how these could be achieved. He has made several important discoveries which here are exemplified by his chiral epoxidation. In 1980 he carried out successful experiments that led to a practical method for the catalytic asymmetric oxidation of allylic alcohols to chiral epoxides. This reaction utilised the transition metal titanium (Ti) and chiral ligands and gave high enantiomeric excess. Epoxides are useful intermediary products for various types of synthesis. This method opened up the way for great structural diversity and has had very wide applications in both academic and industrial research. The synthesis of the epoxide (R)-glycidol is shown in figure 7. Glycidol is used in the pharmaceutical industry to produce beta-blockers, which are used as heart medicines. Many scientists have identified Sharpless' epoxidation as the most important discovery in the field of synthesis during the past few decades. Consequences and applications Many of the applications of this year's Nobel Laureates' pioneering work have already been discussed. It is especially important to emphasise the great significance of their discoveries and improvements for industry. New drugs are the most important application, but we may also mention the production of flavouring and sweetening agents, and insecticides. This year's Nobel Prize in Chemistry shows that the step from basic research to industrial application could sometimes be a short one. All
around the world many research groups are busy developing
other catalytic asymmetric syntheses that have been inspired
by the Laureates' discoveries. Their discoveries have provided
academic research with many important tools, thereby contributing
to more rapid advances in research – not only in chemistry
but also in materials science, biology and medicine. Their
work gives access to new molecules needed to investigate
hitherto undiscovered and unexplained phenomena in the molecular
world. |
| 2001 Nobel
Prize in Economics. The Royal Swedish Academy of Sciences announces that it has decided to award the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel, 2001, jointly to George A. Akerlof, University of California at Berkeley A. Michael Spence Stanford University, and Joseph E. Stiglitz, Columbia University, USA "for their analyses of markets with asymmetric information". Markets with asymmetric information Many markets are characterized by asymmetric information: actors on one side of the market have much better information than those on the other. Borrowers know more than lenders about their repayment prospects, managers and boards know more than shareholders about the firm's profitability, and prospective clients know more than insurance companies about their accident risk. During the 1970s, this year's Laureates laid the foundation for a general theory of markets with asymmetric information. Applications have been abundant, ranging from traditional agricultural markets to modern financial markets. The Laureates' contributions form the core of modern information economics. George Akerlof demonstrated how a market where sellers have more information than buyers about product quality can contract into an adverse selection of low-quality products. He also pointed out that informational problems are commonplace and important. Akerlof's pioneering contribution thus showed how asymmetric information of borrowers and lenders may explain skyrocketing borrowing rates on local Third World markets; but it also dealt with the difficulties for the elderly to find individual medical insurance and with labour-market discrimination of minorities. Michael Spence identified an important form of adjustment by individual market participants, where the better informed take costly actions in an attempt to improve on their market outcome by credibly transmitting information to the poorly informed. Spence showed when such signaling will actually work. While his own research emphasized education as a productivity signal in job markets, subsequent research has suggested many other applications, e.g., how firms may use dividends to signal their profitability to agents in the stock market. Joseph Stiglitz clarified the opposite type of market adjustment, where poorly informed agents extract information from the better informed, such as the screening performed by insurance companies dividing customers into risk classes by offering a menu of contracts where higher deductibles can be exchanged for significantly lower premiums. In a number of contributions about different markets, Stiglitz has shown that asymmetric information can provide the key to understanding many observed market phenomena, including unemployment and credit rationing. For more than two decades, the theory of markets with asymmetric information has been a vital and lively field of economic research. Today, models with imperfect information are indispensable instruments in the researcher's toolbox. Countless applications extend from traditional agricultural markets in developing countries to modern financial markets in developed economies. The foundations for this theory were established in the 1970s by three researchers: George Akerlof, Michael Spence and Joseph Stiglitz. They receive the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel, 2001, "for their analyses of markets with asymmetric information". Markets with Asymmetric Information Why are interest rates often excessively high on local lending markets in Third World countries? Why do people who want to buy a good used car turn to a dealer rather than a private seller? Why does a firm pay dividends even if they are taxed more heavily than capital gains? Why is it advantageous for insurance companies to offer clients a menu of contracts where higher deductibles can be exchanged for lower premiums? Why do rich landowners not bear the entire harvest risk in contracts with poor tenants? These questions exemplify familiar – but seemingly different – phenomena, each of which has posed a challenge to economic theory. This year's Laureates proposed a common explanation and extended the theory when they argumented the theory with the realistic assumption of asymmetric information: agents on one side of the market have much better information than those on the other side. Borrowers know more than the lender about their repayment prospects; the seller knows more than buyers about the quality of his car; the CEO and the board know more than the shareholders about the profitability of the firm; policyholders know more than the insurance company about their accident risk; and tenants know more than the landowner about their work effort and harvesting conditions. More specifically, Akerlof showed that informational asymmetries can give rise to adverse selection on markets. Due to imperfect information on the part of lenders or prospective car buyers, borrowers with weak repayment prospects or sellers of low-quality cars crowd out everyone else from the market. Spence demonstrated that under certain conditions, well-informed agents can improve their market outcome by signaling their private information to poorly informed agents. The management of a firm can thus incur the additional tax cost of dividends to signal high profitability. Stiglitz showed that an uninformed agent can sometimes capture the information of a better-informed agent through screening, for example by providing choices from a menu of contracts for a particular transaction. Insurance companies are thus able to divide their clients into risk classes by offering different policies, where lower premiums can be exchanged for a higher deductible. George Akerlof Akerlof's 1970 essay, "The Market for Lemons" is the single most important study in the literature on economics of information. It has the typical features of a truly seminal contribution – it addresses a simple but profound and universal idea, with numerous implications and widespread applications. Here Akerlof introduces the first formal analysis of markets with the informational problem known as adverse selection. He analyses a market for a good where the seller has more information than the buyer regarding the quality of the product. This is exemplified by the market for used cars; "a lemon" – a colloquialism for a defective old car – is now a well-known metaphor in economists' theoretical vocabulary. Akerlof shows that hypothetically, the information problem can either cause an entire market to collapse or contract it into an adverse selection of low-quality products. Akerlof also pointed to the prevalence and importance of similar information asymmetries, especially in developing economies. One of his illustrative examples of adverse selection is drawn from credit markets in India in the 1960s, where local lenders charged interest rates that were twice as high as the rates in large cities. However, a middleman who borrows money in town and then lends it in the countryside, but does not know the borrowers' creditworthiness, risks attracting borrowers with poor repayment prospects, thereby becoming liable to heavy losses. Other examples in Akerlof's article include difficulties for the elderly to acquire individual health insurance and discrimination of minorities on the labor market. A key insight in his "lemons paper" is that economic agents may have strong incentives to offset the adverse effects of information problems on market efficiency. Akerlof argues that many market institutions may be regarded as emerging from attempts to resolve problems due to asymmetric information. One such example is guarantees from car dealers; others include brands, chain stores, franchising and different types of contracts. A timely example might further illustrate the idea that asymmetric information can generate adverse selection. At first, firms in a new sector – such as today's IT sector – might seem identical to an uninformed bystander, while some "insiders" may have better information about the future profitability of such firms. Firms with lower than average profitability will therefore be overvalued and more inclined to finance new projects by issuing their own shares than high-profitability firms which are undervalued by the market. As a result, low-profitability firms tend to grow more rapidly and the stock market will initially be dominated by "lemons". When uninformed investors eventually discover their mistake, share prices fall – the IT bubble bursts. Apart from his research on asymmetric information, Akerlof has developed economic theory with insights from sociology and social anthropology. His most noteworthy contributions in this genre concern efficiency on labor markets. Akerlof points out that emotions such as reciprocity towards an employer or fairness towards colleagues can prompt wages to be set so high as to induce unemployment. He has also examined how social conventions such as the caste system may have unfavorable effects on economic efficiency. As a result of these studies, Akerlof's research is also well known and influential in other social sciences. Michael Spence Spence asked how better informed individuals on a market can credibly transmit, "signal", their information to less informed individuals, so as to avoid some of the problems associated with adverse selection. Signaling requires economic agents to take observable and costly measures to convince other agents of their ability or, more generally, of the value or quality of their products. Spence's contribution was to develop and formalize this idea as well as to demonstrate and analyze its implications. Spence's pioneering essay from 1973 (based on his PhD thesis) deals with education as a signal of productivity on the labor market. A fundamental insight is that signaling cannot succeed unless the signaling cost differs sufficiently among the "senders", i.e., job applicants. An employer cannot distinguish the more productive applicants from those who are less productive unless the former find it sufficiently less costly to acquire an education that the latter choose a lower level of education. Spence also pointed to the possibility of different "expectations-based" equilibria for education and wages, where e. g. men and white receive a higher wage than women and black with the same productivity. Subsequent research contains numerous applications which extend this theory and confirm the importance of signaling on different markets. This covers phenomena such as costly advertising or far-reaching guarantees as signals of productivity, aggressive price cuts as signals of market strength, delaying tactics in wage offers as a signal of bargaining power, financing by debt rather than by issuing new shares as a signal of profitability, and recession-generating monetary policy as a signal of uncompromising commitment to reduce stubbornly high inflation. An early example in the literature concerns dividends. Why do firms pay dividends to their shareholders, knowing full well that they are subject to higher taxes (through double taxation) than capital gains? Retaining the profits within the firm would appear as a cheaper way to favor the shareholders through the capital gains of a higher share price. One possible answer is that dividends can act as a signal for favorable prospects. Firms with "insider information" about high profitability pay dividends because the market interprets this as good news and therefore pays a higher price for the share. The higher share price compensates shareholders for the extra tax they pay on the dividends. In addition to his research on signaling, Spence was a forerunner in applying the results and insights of the 1996 economics laureates, Vickrey and Mirrlees, to the analysis of insurance markets. During the period 1975-1985, he was one of the pioneers in the wave of game-theory inspired work that clarified many aspects of strategic market behavior within the so-called new theory of industrial organization. Joseph Stiglitz One of Stiglitz's classical papers, coauthored with Michael Rothschild, formally demonstrated how information problems can be dealt with on insurance markets where the companies do not have information on the risk situation of individual clients. This work is an obvious complement to Akerlof's and Spence's analyses by examining what actions uninformed agents can take on a market with asymmetric information. Rothschild and Stiglitz show that the insurance company (the uninformed party) can give its clients (the informed party) effective incentives to "reveal" information on their risk situation through so-called screening. In an equilibrium with screening, insurance companies distinguish between different risk classes among their policyholders by offering them to choose from a menu of alternative contracts where lower premiums can be exchanged for higher deductibles. Stiglitz and his numerous coauthors have time and again substantiated that economic models may be quite misleading if they disregard informational asymmetries. Their common message has been that in the perspective of asymmetric information, many markets take on a completely different guise, as do the conclusions regarding appropriate forms of public-sector regulation. Stiglitz has analyzed the implications of asymmetric information in many different contexts, varying from unemployment to the design of an optimal tax system. Several of his essays have become important stepping stones for further research. One example is Stiglitz's work with Andrew Weiss on credit markets with asymmetric information. Stiglitz and Weiss show that in order to reduce losses from bad loans, it may be optimal for bankers to ration the volume of loans instead of raising the lending rate. Since credit rationing is so common, these insights were important steps towards a more realistic theory of credit markets. They have also had a substantial impact in the domains of corporate finance, monetary theory and macroeconomics. In collaboration with Sanford Grossman, Stiglitz analyzed efficiency on financial markets. Their key result is known as the Grossman-Stiglitz paradox: if a market were informationally efficient, i.e., all relevant information is reflected in market prices, then no single agent would have sufficient incentive to acquire the information on which prices are based. Stiglitz is also one of the founders of modern development economics. He has shown that asymmetric information and economic incentives are not merely academic abstractions, but highly concrete phenomena with far-reaching explanatory value in the analysis of institutions and market conditions in developing economies. One of his first studies of information problems dealt with sharecropping, an ancient, though still common, form of contracting. A sharecropping contract stipulates that the harvest should be divided between a landowner and his tenant in fixed shares (usually half each). Since the landowner is usually richer than the tenant, it would seem advantageous to both parties to let the landowner bear the entire risk. But such a contract would not give the tenant strong enough incentives to cultivate the land efficiently. Considering the landowner's inferior information about harvest conditions and the tenant's work effort, sharecropping is in fact the optimal solution for both parties. Joseph Stiglitz's many contributions have transformed the way economists think about the working of markets. Together with the fundamental contributions by George Akerlof and Michael Spence, they make up the core of the modern economics of information. — Useful Links/Further Reading — Advanced scientific information (PDF): |
| 2000
The Nobel Prize in Physics is announced to go
with one half jointly to Zhores Ivanovich
Alferov, 70, A.F. Ioffe Physico-Technical Institute,
St. Petersburg, Russia, and Herbert Kroemer,University
of California at Santa Barbara, California, USA, "for
developing semiconductor heterostructures used in high-speed-
and opto-electronics" and one half to Jack
S. Kilby, 76, Texas Instruments, Dallas, Texas, USA,
"for his part in the invention of the integrated circuit" The researchers' work has laid the foundations of modern information technology, IT, particularly through their invention of rapid transistors, laser diodes, and integrated circuits (chips). Modern information technology In today's society increasing amounts of information flow from our computers out through the optical fibres of the Internet and through our mobile telephones to satellite radio links all over the world. Two simple but fundamental requirements are put on a modern information system for it to be practically useful. It must be fast, so that large volumes of information can be transferred in a short time. The user's apparatus must be small so that there is room for it in offices, homes, briefcases or pockets. Through their inventions the year 2000 Nobel Laureates in physics have laid a stable foundation for modern information technology. Zhores I. Alferov and Herbert Kroemer have invented and developed fast opto- and microelectronic components based on layered semiconductor structures, termed semiconductor heterostructures. Fast transistors built using heterostructure technology are used in e.g. radio link satellites and the base stations of mobile telephones. Laser diodes built with the same technology drive the flow of information in the Internet's fibre-optical cables. They are also found in CD players, bar-code readers and laser pointers. With heterostructure technology powerful light-emitting diodes are being built for use in car brake-lights, traffic lights and other warning lights. Electric bulbs may in the future be replaced by light-emitting diodes. Jack S. Kilby is being rewarded for his part in the invention and development of the integrated circuit, the chip. Through this invention microelectronics has grown to become the basis of all modern technology. Examples are powerful computers and processors which collect and process data and control everything from washing machines and cars to space probes and medical diagnostic equipment such as computer tomographs and magnetic resonance cameras. The microchip has also led to our environment being flooded with small electronic apparatuses, anything from electronic watches and TV games to mini-calculators and personal computers. Zhores I. Alferov born 15 March 1930 in Vitebsk, White Russia, then the Soviet Union. Doctor's degree in physics and mathematics 1970 at A.F. Ioffe Physico-Technical Institute in St. Petersburg (then Leningrad), Russia. Director of this Institute since 1987. http://194.85.224.34/pti00002.html Herbert Kroemer born 1928 in Germany. Doctor's degree in physics 1952 at University of Göttingen. Employed among other places at RCA Laboratories, Princeton, NJ, USA 1954-57 and at Varian Associates, Palo Alto, CA, USA, 1959-66. Professor of Physics, University of Colorado, Boulder, 1968-76 and subsequently University of California at Santa Barbara, USA. http://www.ece.ucsb.edu/Faculty/Kroemer/default.html Jack S. Kilby born 8 November 1923 in Jefferson City, Missouri, USA. Employed at Texas Instruments since 1958. Professor at Texas A&M University 1978-85. http://www.ti.com/corp/docs/kilbyctr/jackstclair.shtml — Se otorga el premio Nobel de Física a Jack S. Kilby, por el primer circuito integrado, precursor del chip, 42 años después del hallazgo. Comparte el premio con Herbert Kroemer y Zhores Alfiorov, que desarrollaron los dispositivos semiconductores de alta velocidad. More information: http://www.nobel.se/announcement/2000 Useful links/Further reading |
