Blockchain Papers

Milton Harris, Artur Raviv

No abstract is available for this record.

Vivian Wing-Wah Yam, Chi-Kwan Li, Chui-Ling Chan

No abstract is available for this record.

Eli Amir, Yoav Ganzach

No abstract is available for this record.

Vito Albino, A.Claudio Garavelli, Giovanni Schiuma

No abstract is available for this record.

Jun Cai, Tim Loughran

No abstract is available for this record.

Thomas A Stoffregen, L.James Smart

No abstract is available for this record.

Claude Alain, David L. Woods, Robert T. Knight

No abstract is available for this record.

Daniel Immergluck, Erin Mullen

The declining federal role in economic development in distressed urban areas and concerns over the problems associated with metropolitan decentralization necessitate increased attention to the intrametropolitan distribution of business development programs. We examine the distribution of business loans made by the U.S. Small Business Administration's 504 development company program in the Chicago metro-politan area over a 5-year period and find that, after controlling for firm density, firm size, and industrial mix, higher income areas and outlying zip codes receive more loans than lower income and closer-in areas. We suggest a number of supply-and demand-side explanations for such patterns, call for measures to direct the flow of 504 financing more to lower income areas, and call for examining more loan and subsidy programs for their effects on intrametropolitan business development patterns.

Amit Dar

This summary addresses the reform of vocational education and training in China, reviewing the successful economic reforms pursued since 1978, and its labor market structure. The broad policy of the government is to move to a market system, but the major issue is whether an effective, and efficient market system, can be achieved through a process of small changes, while maintaining the existing structures. Vocational education, and training are analyzed, along with major management, costs, and financing issues. Notable reforms reveal major obstacles, such as the costs involved in improving, and expanding training facilities, as well as institutional capacity development. While decentralization has been devolved to provincial, county, and city levels, greater cost-sharing, and private provision for higher, and secondary level education, and training, are being officially encouraged. In addition, there is an improved coordination through local funding mechanisms for in-service training, from government, enterprises, vocational schools, and other training organizations.

Douglas Jechoutek Barnes

option in sustainable energy. Rusting monuments to past failures attest that this “autonomous” technology must operate within a frame of sustainable energy development where many systems interact – the power sector, financial markets, social systems, institutional structures, policy frameworks, business climates, political environments, service infrastructures, cultural settings and so on. In the matter of financing renewable energy, a novel approach is needed. Unique financial instruments are required to complement new scale economies, cost profiles, risks, and benefits. The World Bank Group is reflecting that shift in perspective through its new renewable energy operations, the Solar Development Corporation, the Renewable Energy and Energy Efficiency Fund, and other mechanisms. At the sectoral level, sustainable renewable energy development demands a return to basics. Sound sectoral reform and rational incentives are necessary to make the power sector a friendly environment for renewables. It is in these areas that the World Bank can make its most important contribution to sustainable energy. The message is becoming clearer; success takes time and demands the patient laying down of an institutional groundwork to support innovative delivery mechanisms. Financing Decentralized Renewable Energy: New Approaches

Amit Sahai, Salil Vadhan

. We give several efficient transformations for manipulating the statistical difference (variation distance) between a pair of probability distributions. The effects achieved include increasing the statistical difference, decreasing the statistical difference, "polarizing" the statistical relationship, and "reversing" the statistical relationship. We also show that a boolean formula whose atoms are statements about statistical difference can be transformed into a single statement about statistical difference. All of these transformations can be performed in polynomial time, in the sense that, given circuits which sample from the input distributions, it only takes polynomial time to compute circuits which sample from the output distributions. By our prior work (see FOCS 97), such transformations for manipulating statistical difference are closely connected to results about SZK, the class of languages possessing statistical zero-knowledge proofs. In particular, some of the transformation...

G Aronica, B Hankin, K Beven

No abstract is available for this record.

Alan L. Lewis

We provide exact solutions for two closely related valuation problems in continuous‐time finance. The first problem is to value generalized European‐style options on stocks that pay dividends at a constant dollar rate. The second problem is to find the yield curve associated with the economy of R. C. Merton's “An Asymptotic Theory of Growth Under Uncertainty.” In Merton's economic growth model, the interest rate process has a volatility linear in the rate level and a linear/quadratic drift. Both problems are solved by an eigenfunction expansion technique. The main technical difficulty is handling the problem of payoff functions that are not square‐integrable with respect to the natural weight function of the models.

Paul H. Edelman

In these pages,' Steven Lubet recently reviewed A Tour of Calculus, by David Berlinski.2 Inspired by both beauty of calculus and Berlinski's description of it, Lubet waxes poetic on many parallels between law and calculus. It is completely understandable--even admirablethat one might be led to ruminations on relationship between calculus and one's own discipline. There is little doubt that subject of calculus stands as one of great intellectual feats of Western thought. It has had profound implications for physics, engineering, economics and many other disciplines-so why not law? Alas, these philosophical musings would be more persuasive had Professor Lubet better understood what it was that he was writing about. Lubet's errors come in two types. first is just a misunderstanding of history, but it is a misunderstanding that unfortunately forms basis for an entire section of his review. second type of error is more fundamentally mathematical: he does not distinguish between a definition and a theorem. Just as Lubet draws legal lessons from calculus, we can draw legal parallels from his mistakes. While some of these might be comforting, others will be more unsettling. As noted by Lubet, development of calculus was done more or less simultaneously in mid-17th century by Sir Isaac Newton and Gottfried Wilhelm Leibniz. Leibniz based much of his development of subject on idea of an infinitesimal, a class of numbers that are smaller than any other number. According to Lubet, the `infinitesimals' turn out to be a futile fiction, notwithstanding Liebnitz's [sic] own endorsement of them. In 1734, Bishop Berkeley that they do not and cannot exist.3 Lubet goes on in Part III to draw a number of legal parallels to this discrediting of idea of infinitesimals. While legal conclusions he draws from these events may well be true, Lubet cannot base them on invalidity of infinitesimals: fact of matter is that Leibniz was right. To be fair to Lubet, ultimate vindication of Leibniz's belief in infinitesimals is hidden in a footnote by Berlinski: The development of [non-Archimedean] fields by logician Abraham Robinson in twentieth century has made possible development of calculus entirely along lines anticipated by Leibnitz [sic].4 Nevertheless, anyone with serious mathematical training would not have needed Berlinski's footnote; Lubet's error highlights danger of relying on secondhand knowledge of a field quite different from one's own. Moreover, culpability aside, Lubet has lost foundation for legal insights he draws from purported invalidity of infinitesimals. And what of supposed proof' of Bishop Berkeley? Berlinski writes that [w]riting in 1734, Bishop Berkeley wasted no time in attacking very idea of infinitesimals, and later says that [1]ooking backward, we can see that Berkeley was entirely correct,5 but never claims that Bishop Berkeley proved conclusively anything about existence of infinitesimals. Indeed, he couldn't have, since by appropriately generalizing idea of a number, Abraham Robinson was able to define them. Lubet should be more careful in using term proof' in context of mathematics. Lubet sees more parallels between computation of area under a curve and way that legal trials proceed by means of accretion of detail.6 Surprisingly, Lubet doesn't draw obvious parallel, that just as sum of more and more rectangles gives better and better approximations for area under a curve, as a trial proceeds evidence presented gives a better and better approximation of truth. He instead focuses on error in mathematical approximation: An integral combines rectangles until limit of error approaches zero, but error-zone never actually becomes zero. …

Bernard Jégou

Intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility ( 8). Thanks to this technique, it is now possible to achieve fertilization and pregnancy when the number of spermatozoa in the ejaculate is extremely low. I therefore understand the enthusiasm of clinicians such as Dr Baker, whose practice puts them in a position from which they can appreciate the benefits brought by this technique to patients affected by the most severe forms of infertility. I also appreciate the value of the efforts made by different in vitro fertilization (IVF) groups, starting with that of Professor van Steirteghem and his collaborators, who are doing their best to develop the necessary follow-up of the children born after the ICSI procedure. My major concern is with the way in which assisted reproduction techniques generally emerge, including those that may develop in the wake of ICSI. These new microassisted human fertilization procedures are: testicular sperm extraction (TESE) to alleviate male factor infertility due to obstructive azoospermia ( 2) or due to azoospermia resulting from spermatogenetic maturation arrest ( 3; 5; 9); elongating and elongated spermatid injection (ELSI; 14) when spermatozoa are absent;␣round spermatid injection (ROSI; 13; 14) and round spermatid nuclei injection (ROSNI; 6; Sofikitis et al., 1995), when late spermatids are missing; and, very recently, secondary spermatocyte injection (SESI; 11) when spermatids are not available. These new techniques bypass the sperm selection processes that have evolved to regulate vertebrate fertilization (ICSI; 1), various steps of spermiogenesis (ROSI and ROSNI), the complete spermiogenetic process and the equatorial stage of division of meiotic cells (SESI). The first aspect that is deeply disturbing is that the development and use of these techniques were not originally published in the form of true scientific papers, i.e. papers that are peer-reviewed, that contain proof the assertions made (figures, pictures), and that provide all the information required for verification (detailed protocols). Instead, the first information on these revolutionary technologies was published in the form of press releases and short `letters to the Editor' of the Lancet (ELSI; 5; ICSI; 8) or of the New England Journal ofMedicine (ROSI; 13) or in the form of conference reports (ROSNI, SESI; 10, 11). These major distortions of the accepted method of scientific communication, concerning an issue as important as assisted reproduction which always receives tremendous media attention, raises the␣question of the responsibility of some of the clinicians in␣the IVF field. They also raise the question of the deontology of the editorial boards of some medical journals which seem to chase the scoop, rather than rigorously informing the scientific community on the conditions under which these human experiments were permitted (ethical committees?) and performed (reality, security, repeatability?) and how the outcome of these experiments is being followed up. There is another reason for disquiet. These new techniques are used to create human beings. However, in most cases they do not result from the logical extension of thorough animal experimentation designed to prepare the ground for the transfer to the clinical field, or of clearly planned and well-thought-out clinical decisions. Although I agree with Dr Baker that many important medical breakthroughs have developed fortuitously, in the field of reproduction it is striking that the fortuitousness is systematic, or almost. Instead, the emergence of the microinjection techniques has been presented as the consequence of an `accident' in the case of ICSI ( 8), or as totally opportunistic in the case of ROSI (Tesarick et al., 1995) and ELSI ( 5). SESI ( 11) was presented as the extrapolation of animal studies. In fact, these studies had only been performed using fertile animals, not animals affected by spermatogenic arrest, and were performed shortly before experimentation with human subjects, and by a single laboratory. There was therefore no opportunity for validation by the scientific community. As a consequence, not only do the practitioners of these techniques lack the minimum biological background that is always required before experimenting on human beings but, in most cases, no ethical approval was sought and therefore granted to develop these extremely audacious techniques. A further consequence is that the practitioners were and still are, de facto, unable to provide their patients with even the minimal information required for obtaining `informed consent', in particular when cells other than spermatozoa are used. Several arguments are often raised when the value of animal experimentation in assisted reproduction is discussed with IVF practitioners. The first is that several previous major advances in assisted reproduction technology were not preceded by any detailed animal studies (e.g. embryo freezing) and have not had any apparent negative consequence. This leads to the view that new technological jumps can be made in the absence of prior animal experimentation. Secondly, it is often said that, for technical reasons, it is not possible to develop animal models and/or that there is no adequate animal model. The third is that `scientists have not proved that these new techniques are dangerous'. Fourthly, animal experimentation is often presented as costly and time-consuming. This explains in turn why the few laboratories which are at the interface between the basic and clinical fields, and therefore have both the technical and intellectual skills, have not developed long-term animal experiments. The first of these arguments is akin to playing Russian roulette, and is an argument which is completely unacceptable in medical practice. It is also unclear whether enough time has elapsed or if the proper means are available to assess objectively all aspects of the possible consequences of the application of microinjection techniques on the progeny. There is no doubt that the techniques of microinjection of spermatozoa and, a fortiori, of other testicular cells, represents an increased risk to the offspring, because a significant proportion of the men requiring microinjection assistance are infertile for genetic reasons. Furthermore, because different steps of spermatogenesis are bypassed when immature germ cells are used, and because the identification of these cells cannot be accurate, additional and increasing risks are certainly taken with TESE, ELSI, ROSI, ROSNI and SESI. This should, a␣fortiori, lead to even more cautiousness (and modesty?) among IVF practitioners. Finally, the argument that no previous catastrophe has occurred in the field of assisted reproduction totally ignores the unprecedented social demand for safety in the fields of health and medicine resulting from the `contaminated blood scandal' and the other recent medical and scientific problems (e.g. contaminated pituitary extracts and the `mad cow' affairs). I remind those who pretend (or who used to pretend) that it is extremely difficult or impossible to set up animal models that this argument was raised in the past to justify, for example, 8) performing the first ICSI directly on a human being, before 7) succeeded in setting up ICSI in the mouse. This clearly shows that when a topic becomes `hot' enough, skills, time and money can be found to develop animal models. Furthermore, the assertion that `there is no adequate animal model' ignores the fact that animal experimentation is mandatory and extremely constraining for the pharmaceutical industry. Initially, when the first safety assessment guidelines were implemented for drugs, this occurred because of the catastrophic consequences of the thalidomide tragedy, and was not due to a consensus on the existence of an ideal animal model. For those who argue that the onus is on basic scientists to prove that these new technologies are dangerous, I would answer that technology should serve science, not dictate to science. Of course, when circumstances allow it one of the major roles of science is to provide the knowledge that allows understanding of how and why a given therapy works or does not work. Concerning the cost of programmes involving animal experimentation, it should be remembered that the health of human beings is at stake. Furthermore, if we consider the huge profits made by the `assisted reproduction industry', which includes the revenues of clinics, clinicians and industry (e.g. hormone manufacturers), then the absence of investment by these beneficiaries in basic and experimental research on assisted reproduction is striking. By contrast, note, for example, that the pharmaceutical industry invests an estimated 15–20% of its sales in research and development of new drugs. Finally, it is also important to note two major contradictions in the views of some of the pioneers of microinjection techniques: first, after having claimed that animal studies are not really relevant to human trials, they now want to use, or more accurately abuse, the few existing data arising from animal experimentation (e.g. SUZI and ICSI performed in normal animals, not in animals with spermatogenic arrest, and data on genomic imprinting) to justify in retrospect the experimentation performed in humans (see 4); secondly, while advocating caution in the use of microinjection procedures with immature germ cells ( 12), they themselves diffuse these techniques worldwide, including to countries where, a priori, there is very little chance that there will be follow-up studies, for example. Readers of this paper may believe that I am hostile to the development of the technology of assisted reproduction, but this is not the case. My goal is to highlight the singularity of the emergence of the most recent IVF technologies and some universal principles of science and medicine. One of these principles is that animal studies must always precede action on human subjects, and should always be verified before being applied. Being a reproductive biologist, the increasing rift between basic science and technology in the domain of assisted reproduction is a matter of great frustration and anxiety to me. As a simple citizen, I remember that 40 years ago, Hannah Arendt wrote that `if knowledge [in the modern meaning of know-how] and thought separate irretrievably, we will become the playthings and slaves, not so much of our machines, but of our practical knowledge'. I thank Professors M. C. Orgebin-Christ and G. Waites, as well as Professor Kamal Zaki for giving me the opportunity to present the ideas summarized in this article before the participants of the VIth International Congress of Andrology in Salzburg (25–29 May 1997) and the 10th Annual Congress of Andrology in Cairo (17–18 December 1997).

Helena Munín

The introduction of ‘freer’ forms of organization and financing into the Latin American educational systems about 20 years ago parallels similar developments in the contexts of neo‐liberal policies in the USA, Great Britain and, more recently, in Eastern Europe. This article will highlight the effects of ‘school autonomy’, decentralization, and privatization in the Latin American educational systems. In so doing, I will focus on the analysis of educational policy development in Chile and Argentina, based in part on my own research results. The results demonstrate that ‘freer’ forms of organization and financing have not proven to be positive for the progressive distribution of education, democratization and the consideration of diversity—and also not for the (difficult to measure) categories of ‘quality’ and ‘efficiency’ of education. These findings contribute to question whether the neo‐liberal forms of organization and financing of educational systems in Latin America are important factors in the realization of these goals.

Uriel Feige, Joe Kilian

We present a new technique, inspired by zero-knowledge proof systems, for proving lower bounds on approximating the chromatic number of a graph. To illustrate this technique we present simple reductions from max-3-coloring and max-3-sat, showing that it is hard to approximate the chromatic number within /spl Omega/(N/sup /spl delta//), for some /spl delta/>0. We then apply our technique in conjunction with the probabilistically checkable proofs of Bellare, Goldreich and Sudan (1995), and of Hastad (1996), and show that it is hard to approximate the chromatic number to within /spl Omega/(N/sup 1-/spl epsiv//) for any E>0, assuming NP/spl sub/ ZPP. Here, ZPP denotes the class of languages decidable by a random expected polynomial-time algorithm that makes no errors. Our result matches (up to low order terms) the known gap for approximating the size of the largest independent set. Previous 0(N/sup /spl delta//) gaps for approximating the chromatic number (such as those by Lund and Yannakakis (1994), and by Furer (1995)) did not match the gap for independent set, and do not extend beyond /spl Omega/(N/sup 1/2-/spl epsiv//).

Coralie Bryant

The debate around the relative roles of markets versus bureaucrats took on renewed life with the end of the Cold War. The public policy debate shifted from focusing on the public sector to emphasizing markets and their ability to innovate, decentralize, use incentives and meet needs more effectively. Yet there remains in this public policy debate a stunning silence about the absence of property rights for the rural poor. This article focuses on the need to put property rights for the rural poor--the need for land reform--back on the international policy agenda. The first half of the article examines current land reform paradigms and looks at what has been learned, focusing on Brazil as a case study The second half of the article moves from what has been done to a discussion of where future research and operational work should go from here. There are 1.3 billion people around the world who live on less than U.S.$1 a day.(1) Even though urbanization has been one of the major features of development and change in the past decade, the majority of these poor still live in rural areas. Furthermore, there are rural roots to the urban poverty seen in most countries, as those without assets migrate to urban or semi-urban areas searching for work. Thus redistribution of assets is central to long-run progress on reducing poverty in both the city and the countryside. Researchers Michael Lipton and Jacques van der Gaag point out: For poverty reduction to succeed, the poor need some autochthonous source of income and safety. That is, they need to have an alternative, in the market place and in the polity, not to depend on a patron, monopolist or bureaucrat. Providing the poor with access to productive land is usually regarded as crucial.(2) Land reform is one of the most central steps in this process. The effectiveness of land-reform programs in improving productivity and reducing rural poverty relies on many factors including land quality, access to technology and strong local agricultural markets. However, access to land is the single most important prerequisite for improving economic conditions among the rural poor. Precisely because of the salience of land reform to the reduction of rural poverty, one of the major recommendations of this paper is that international donors should recommit themselves to land reform and begin financing the analytical work and technical assistance it requires. The current general silence and limited operational programming of donors on land reform exacerbates the rural poverty problem.(3) CONCEPTUAL FRAMEWORK Over two decades ago, Peter Dorner, a major authority on land reform, cautioned: Land reform is so intimately related with the whole development process that one feels the need to deal with issues of development in general as well as with those more specifically identified with land reform. That requires simplification of complex and nationally specific experiences. No single body of theory encompasses all the strategic variables.(4) Dorner's definition of land reform includes measures to redistribute land in favor of peasants and small farmers and ... embraces consolidation and registration in areas where customary tenure is prevalent and also land settlement on new lands.(5) He places an additional emphasis on the need to make changes in tenancy rights. Each of these aspects goes to the core of rural politics, and nothing about them is easily simplified. Indeed, to think of land reform as only a technocratic or economic problem is a mistake. It is a political economy problem with economic and social consequences amenable to resolution through good technical skills and political change. As such, land reform is a central part of the whole development process. While development economists and agricultural economists have done most of the conceptual work on land reform, more recently attention has shifted to the ancillary fields of institutional theory (including organization theory), development management and law. …

Gerald R. Ferris, Michelle M. Arthur, Howard M. Berkson, David M. Kaplan · 6 authors

No abstract is available for this record.

Ruth Wedgwood

In a world of sovereign states, gathering evidence is one of the major challenges for the new international criminal tribunals. The decision in Prosecutor v. Blaškić, by the Appeals Chamber of the International Criminal Tribunal for the former Yugoslavia, shows some of the difficulties. The Tribunal finds it has the power to issue compulsory orders to sovereign states for the production of evidence, although not to issue a subpoena as such. The Tribunal also assumes the power to review a state's national security privilege, a holding that may challenge the more protective provisions of the new Rome treaty for a permanent International Criminal Court. However, the Appeals Chamber's declaration that there is no power to summon particular government officials, even for eyewitness testimony, that document production must be limited, and that its orders cannot be directly enforced, may hobble the Tribunal's capacity to muster the necessary proof at trial.

Istemi S. Demirag

No abstract is available for this record.

Adam Tickell

No abstract is available for this record.

Yin-Wong Cheung, Lilian K. Ng

No abstract is available for this record.

Peyman Faratin, Carles Sierra, Nick R. Jennings

No abstract is available for this record.