An identity-based signcryption scheme with (t,n) shared unsigncryption is proposed, which is the integration of the signcryption scheme, the (t,n) threshold scheme and zero knowledge proof for the equality of two discrete logarithms based on the bilinear map. In this scheme, any third party can verify the validity of the signature, but only more than t members in the recipient group can cooperatively recover the message m. As compared to the Zhang et al.'s signcryption scheme with (t,n) shared unsigncryption based on discrete logarithms, the proposed scheme has the following advantages: it provides both public verifiability and forward security; the key management problem is simplified because of using identity-based cryptosystem.
Este é um trabalho sobre desenhos institucionais e seus resultados redistributivos, que toma como objeto de análise a política de saúde no Brasil. O modelo de descentralização do Sistema Único de Saúde – SUS –caracteriza-se por concentrar autoridade no governo federal, assim como financiar a política de saúde através de um sistema abrangente de transferências interregionais. Este sistema pretendeu, em período recente, acentuar seus objetivos redistributivos com a introdução do Piso da Atenção Básica – PAB, na Norma de Operação Básica – NOB98. Este trabalho pretende examinar a extensão em que um sistema descentralizado, cujo desenho institucional concentra autoridade no governo central para implementar políticas com finalidades redistributivas, logra reduzir as diferenças regionais no acesso aos serviços públicos. Para isto, testaremos inicialmente a extensão do processo de descentralização da política de saúde no Brasil, para em seguida analisarmos a extensão da equalização na provisão de serviços de saúde. PALAVRAS-CHAVE: política de saúde, descentralização, federalismo, desenhos institucionais, Brasil LOCAL CONDITIONANTS OF DECENTRALIZATION OF HEALTH POLICIES This paper is about institutional designs and ist redistributive results, and has as its object of analysis the Brazilian Health Policy. The decentralization model of the SUS – United Health System has as its characteristics to concentrate authority on the Federal governmet and financing the health policy through an ample system of interregional transferences. This system intended, in recent times, to increase its redistributive objectives with the intriduction of the PAB – Basic Attention Floor int the NOB98 – Basic Operation Procedure. This paper intends to examine the extension to which a decentralized system, which institutional design concentrates authority on the central government to enforce policies with redistributive intentions, achieves reduction of the regional differences in access to public services. To do this, we will initially test the extent of the decentralization process in Brazilian health policy, and after that we will analyse the extent of equalization on providing health services. KEY WORD: health policy; decentralization; federalism; institutional designs; Brazil. CONDITIONS LOCALES DE LA DECENTRALISATION DES POLITIQUES DE SANTE Cet article sur les schémas institutionnels et les résultas de leur redistribution a pour objet l’analyse de la politique de santé au Brésil. Le modèle de décentralisation du SUS est caractérisé par la concentration de l’autorité dans le gouvernement fédéral, ainsi que par le financement de la politique de santé par un vaste système de transferts interrégionaux. Ce système prétendait récemment souligner ses objectifs de redistribution grâce à l’introduction du PAB, à la NOB98. Cet article prétend examiner jusqu’à quel point un système décentralisé, dont le schéma institutionnel concentre l’autorité dans le gouvernement central pour mettre en oeuvre des politiques à finalité de redistribution, réussit à réduire les différences régionales pour l’accès aux services publics. Pour cela, on examinera d’abord l’étendue du processus de décentralisation de la politique de santé au Brésil, pour analyser ensuite à quel point il est équitable lors de la fourniture des services de santé. MOTS-CLES: politique de santé, décentralisation, fédéralisme, schémas institutionnels, Brésil. Publicação Online do Caderno CRH: http://www.cadernocrh.ufba.br
The past decade has been a period of introspection in the radiological protection community. The International Commission on Radiological Protection (ICRP) has set out to produce a new set of recommendations; a draft document has been produced and made available on the ICRP web site. That draft has been widely reviewed and support for the proposed recommendations has been muted to say the least [1]. A subsequent draft is now being reviewed. As we wait for the final version it seems worthwhile to reaffirm the fundamental base for radiological protection as we practise it. The base is the set of three principles; justification, protection of the individual, and optimization of protection (the ALARA principle). Their importance seemed to be lost in the detail of the initial draft recommendations. I feel that without a clear statement of their primacy in the protection system we are in danger of the minutiae of the recommendations being applied in a far too arbitrary and restrictive way. There was a hint of this in the draft ICRP document on optimization that was available for review earlier this summer, in which it was argued that the so-called precautionary principle had been the driver for the evolution of the ICRP's thinking [2]. Some argue, correctly I believe, that this is not really a principle; it is more a poorly-defined and open-ended method of handling or reacting to uncertainties in our knowledge of risk. We see the precautionary principle rather loosely invoked in some risk management decisions as justifying arbitrary safety factors. `Applying the precautionary principle' sounds more substantial and scientific than just saying `to be on the safe side'. The influence of the principle is far more widespread though. The idea behind the precautionary principle originated in Germany in the 1960s but it was not until 1982 that it was endorsed internationally when the UN included it in the World Charter for Nature. It gained prominence in European treaties and was advocated by the UN Rio Declaration on Environment and Development in 1992. Initially the idea was that `uncertainty does not justify inaction'. The idea evolved and precaution began to take the place of science-based risk assessment and management. By the late 1990s the idea was that uncertainty also required shifting the burden and standard of proof [3]. The principle became `When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context, the proponent of an activity, rather than the public, should bear the burden of proof.' [4,5] In other words, uncertain risk requires forbidding the potentially risky activity until the proponent of the activity demonstrates that it poses no (or acceptable) risk. We are all aware of the impossibility of proving a zero but this wording may sound reasonable provided that the parenthetic `or acceptable' is the operative qualifier. For many though, it is not. Adams has described what he calls the {\it environmentalist paradigm}, in which possibility replaces probability as a criterion for protection regulation, and any agent harmful at high doses is considered harmful at exceedingly low doses [6]. Only zero risk is then acceptable when the precautionary principle is applied. This is a stultifying situation. Morris comments, in a broad-ranging critique, that the precautionary principle not only lacks any clear guidance on when and how it does apply, but perhaps more importantly it is devoid of any limitations of when it does apply [7]. Without such limitations, he notes, the precautionary principle will be a vacuum that can consume any and all products and technologies, since some risk and uncertainty is associated with every human activity. We could conclude that in radiological protection we would have no optimizing; no applying the ALARA principle. Radiation regulations based on the three fundamental ICRP principles have achieved an acceptable level of protection for decades. We should not abandon them to the arbitrariness of the precautionary principle when we have a sound basis for radiological protection in the clearly-enunciated principles of justification, individual dose limitation and optimization of protection. Radiological protection based on these principles includes elements of precaution. Why do we need a precautionary principle? This has been indirectly answered by asking: What if we were to apply the precautionary principle to itself? Its application carries the burden of untold risks and uncertainties. Thus, by its own definition, it should be abandoned [4]. This is not to argue that we should throw caution to the wind. The key is reasonableness. As Nilsson points out, though it is certainly better to be safe than sorry, it is important to distinguish unjustified precautionary action from justifiable precautionary action based on sound science and an appropriate assessment of the costs and benefits of taking action [8]. The precautionary principle fails to distinguish between the two, by elevating to the status of universal `principle' a notion that is only narrowly applicable. In Canada we are fortunate that we have sensible wording in the Federal Nuclear Safety and Control Act that provides the framework for many of the radiological protection regulations in Canada [9]. Part of its stated purpose is the limitation, to a reasonable level , of the risks to the health and safety of persons and the environment. The ICRP principle of dose limitation and the ALARA principle are coherent with this. Further, the Federal Government's Privy Council Office (PCO) has published guidance for its agencies on the application of precaution in science-based decision-making that reinforces the approach we have been taking in radiological protection and, in particular, emphasizes the importance of what is in essence the ALARA principle [10]. It notes that sound scientific information and its evaluation must be the basis for applying precaution. Peer review represents a concrete test for the practical application of precaution to decision making. A peer-review process can assess the soundness of the scientific evidence and its inherent credibility within the scientific community. Scientific advisors should give weight to peer-reviewed science and aim at sound and reasonable evidence on which to base their judgments. Moreover, the science function can be further supplemented by formal, structured and, where warranted, independent advisory processes that include widely recognized and credible individuals. I believe we can heartily subscribe to this. The guidance document lays out five principles that should guide the application of precautionary measures. They should be: Subject to reconsideration, on the basis of the evolution of science, technology and society's chosen level of protection. Proportional to the potential severity of the risk being addressed and to society's chosen level of protection. Non-discriminatory and consistent with measures taken in similar circumstances. Cost-effective, with the goal of generating an overall net benefit for society at least cost, and efficiency in the choice of measures. Finally, where more than one option reasonably meets the above characteristics, then the least trade-restrictive measure should be applied. We can see all three radiological protection principles reflected in this guidance. Particularly important is the emphasis on the link to scientific knowledge, rather than the whims of activist groups, together with the exhortation to assess the real and potential impacts of making a precautionary decision (whether to act or not to act), including social, economic and other relevant factors and risk-risk trade-offs. Apply the ALARA principle in other words. The guidance concludes with the expectation that Canadian agency officials will consider its guiding principles in decision-making and will work together in developing, in consultation with their stakeholders, guidance for the application of precaution in t
The output of a data mining algorithm is only as good as its inputs, and individuals are often unwilling to provide accurate data about sensitive topics such as medical history and personal finance. Individuals maybe willing to share their data, but only if they are assured that it will be used in an aggregate study and that it cannot be linked back to them. Protocols for anonymity-preserving data collection provide this assurance, in the absence of trusted parties, by allowing a set of mutually distrustful respondents to anonymously contribute data to an untrusted data miner.To effectively provide anonymity, a data collection protocol must be collusion resistant, which means that even if all dishonest respondents collude with a dishonest data miner in an attempt to learn the associations between honest respondents and their responses, they will be unable to do so. To achieve collusion resistance, previously proposed protocols for anonymity-preserving data collection have quadratically many communication rounds in the number of respondents, and employ (sometimes incorrectly) complicated cryptographic techniques such as zero-knowledge proofs.We describe a new protocol for anonymity-preserving, collusion resistant data collection. Our protocol has linearly many communication rounds, and achieves collusion resistance without relying on zero-knowledge proofs. This makes it especially suitable for data mining scenarios with a large number of respondents.
Two long-standing open problems exist on the fringe of complexity theory and cryptography: (1) Does there exist a reduction from an NP-complete problem to a one-way function? (2) Do parallelized versions of classical constant-round zero-knowledge proofs for NP conceal every "hard" bit of the witness to the statement proved? We show that, unless the polynomial-hierarchy collapses, black-box reductions cannot be used to provide positive answers to both questions
The Uttaranchal Rural Water Supply and Sanitation Project for India improves the effectiveness of rural water supply and sanitation (RWSS) services through decentralization and the increased role of the Panchayati Raj Institutions and the involvement of local communities in the state of Uttaranchal. There are three components. Component 1: The Rural Water Supply and Sanitation Sector Development will support the state's sector reform process by establishing and enhancing its institutional capacity to implement, manage, and sustain the state's medium-term sector development program through the following subcomponents: (1) capacity-building and strengthening programs; (2) information, education, and communication; (3) sector information system, water quality, and water source discharge monitoring programs; (4) modernization of public procurement and procurement reforms; and (5) sector studies. Component 2: The Rural Water Supply and Sanitation Infrastructure Investments Component aims to improve service and sustainable access to rural water supply and sanitation services by financing the following investments: (1) new investments in water supply schemes and catchment-area protection works; (2) community mobilization and development activities; and (3) sanitation programs. Component 3: Program Management Support and Monitoring and Evaluation includes support: for operational and administrative costs associated with implementing a sector-wide approach to the state's medium-term sector program.
In the present work, a framework is proposed for studying autonomous agents which interact locally yet effect a globally coherent behavior. This problem of locally induced organization is ubiquitous in decentralized multi-robot environments and various micro- and macroscopic biological contexts (e.g., cellular chemotaxis, avian flocking). In analogy with the local equations of motion which arise in various elastic rod and vorticity theories, we pursue this question in a continuum setting where agents are uniquely associated with material points of a virtual filament. The governing dynamics for this filament are chosen so that an established set of control objectives is achieved. The appropriate configuration space of continua is shown to be an infinite dimensional Hilbert Lie group admitting a separable topology. A class of filament models is studied in a Lagrangian formalism on this manifold, leading to a natural curvature feedback law.
Economic and social cohesion between the EU Member States is one of the explicitly stated goals in the Treaty on European Union. The EU's Structural Funds as a part of the Union's regional policies are a mechanism of conditional grants that provides co-financing for growth enhancing investments. Evidence on the effectiveness of the Structural Funds is mixed. While Boldrin and Canova (2001) find no sign of a catch-up effect of regions receiving aid for the period of 1980-1996, Beugelsdijk and Eijffinger (2005) find a positive relationship between (lagged) Structural Funds expenditure and GDP growth at the national level covering 1995-2001. De La Fuente (2002) points to the fact that the inclusion of conditioning variables might also play a crucial role for the results. Ederveen, deGroot and Nahuis (2002) find that Structural Funds themselves have a negative impact on growth. However, the impact turns out to be significantly positive, when interacting variables measuring institutional quality are taken into account. Similarly, Esposti (2005) shows that additional policy measures (spending on CAP) can have significant counter-effects on the effectiveness of Structural Funds expenditure. So far the federal structure of the EU Member States did not attract much attention when the effectiveness of the Structural Funds is considered. Although the EU Commission requires the inclusion of regional authorities and stakeholders in the planning and implementation procedure of programs funded by Structural Funds, one should expect that the performance is better, where the sub-national authorities are more accustomed to pursuing economic policy and implementing programs. This should be the case in states with a higher degree of sub-national autonomy. Using panel-data for a sample of 13 EU Member States from 1960-1995 the effects of Structural Funds on growth are analysed. Then a decentralization index by Stegarescu (2004) is introduced as an interacting variable in order to measure the degree of sub-national autonomy. This paper shows that increasing sub-national autonomy has a significantly positive impact on the effectiveness of the Union's Structural Funds expenditure.
Recently, M. Sekhar gave a digital signature scheme with message recovery, where only a specific verifier can directly check the validity of the signature. A third party can distinguish a valid signature through a zero-knowledge proof protocol. However we find that the proposed scheme is insecure. A forgery attack strategy on M. Sekhar's scheme has been designed; anyone who has a valid signature can forge a signature on an arbitrary message. An improved signature scheme, which can resist the forgery attack and a zero-knowledge proof protocol with which a third party can distinguish a valid signature are presented. Also, the security of the improved scheme is analyzed
We prove a lifting theorem (from any characteristic p to characteristic zero) for holomorphic Picard modular forms of any weight and level. The proof makes use of the knowledge of the geometry of the toroidal compactification of the Picard modular surface.
ABSTRACT The study of household finance is challenging because household behavior is difficult to measure, and households face constraints not captured by textbook models. Evidence on participation, diversification, and mortgage refinancing suggests that many households invest effectively, but a minority make significant mistakes. This minority appears to be poorer and less well educated than the majority of more successful investors. There is some evidence that households understand their own limitations and avoid financial strategies for which they feel unqualified. Some financial products involve a cross‐subsidy from naive to sophisticated households, and this can inhibit welfare‐improving financial innovation.
Rahul Jain, Alexandra Kolla, Gatis Midrijānis, Ben W. Reichardt
Let L be a language decided by a constant-round quantum Arthur-Merlin (QAM)\nprotocol with negligible soundness error and all but possibly the last message\nbeing classical. We prove that if this protocol is zero knowledge with a\nblack-box, quantum simulator S, then L in BQP. Our result also applies to any\nlanguage having a three-round quantum interactive proof (QIP), with all but\npossibly the last message being classical, with negligible soundness error and\na black-box quantum simulator.\n These results in particular make it unlikely that certain protocols can be\ncomposed in parallel in order to reduce soundness error, while maintaining zero\nknowledge with a black-box quantum simulator. They generalize analogous\nclassical results of Goldreich and Krawczyk (1990).\n Our proof goes via a reduction to quantum black-box search. We show that the\nexistence of a black-box quantum simulator for such protocols when L notin BQP\nwould imply an impossibly-good quantum search algorithm.\n
Amy Q. Shen, B. D. Hamlington, Michael Knoblauch, Winfried S. Peters · 5 authors
With the discovery in plants of the proteinaceous forisome crystalloid (Knoblauch, et al. 2003), a novel, non-living, ATP-independent biological material became available to the designer of smart materials for advanced actuating and sensing. The in vitro studies of Knoblauch, et al. show that forisomes (2-4 micron wide and 10-40 micron long) can be repeatedly stimulated to contract and expand anisotropically by shifting either the ambient pH or the ambient calcium ion concentration. Because of their unique abilities to develop and reverse strains greater than 20% in time periods less than one second, forisomes have the potential to outperform current smart materials as advanced, biomimetic, multi-functional, smart sensors or actuators. Probing forisome material properties is an immediate need to lay the foundation for synthesizing forisomebased smart materials for health monitoring of structural integrity in civil infrastructure and for aerospace hardware. Microfluidics is a growing, vibrant technology with increasingly diverse applications. Here, we use microfluidics to study the surface interaction between forisome and substrate and the conformational dynamics of forisomes within a confined geometry to lay the foundation for forisome-based smart materials synthesis in controlled and repeatable environment.
3D Printing in Biomedical Research
Electrowetting and Microfluidic Technologies
Microfluidic and Capillary Electrophoresis Applications
As Jennifer Adams notes in her paper, a number of studies within the U.S., as well as some studies in China and other low- and middle-income countries, have begun to address the ways that communities impact schooling outcomes. The potential role played by communities in local education has strengthened with the shift toward administrative and fiscal decentralization in many developed and developing countries. Often, fiscal decentralization results in a greater reliance on community financing of schooling, which, in turn, strengthens the association between where students live and the quality of educational services they receive (Bray, 1996a, 1996b).
The following provides a review, discussion, and description of how sediment transport pathways are obtained. It excludes the details of the mathematical proof, demonstrating the changes in grain size distributions that occur with transport as contained in McLaren and Bowles (1985). Sediment trend analysis (STA) requires for its data the grain size distributions of sediments collected on regular grid spacing over the aquatic site of interest. The sampled sediments are described in statistical terms (by the moment measures of mean, sorting, and skewness), and the basic underlying assumption is that processes causing sediment transport will affect the statistics of the sediments in a predictable way. For this purpose, a grain size distribution defines for any size class the probability of the sediment being found in that size class. Size classes are defined in terms of the well-known ϕ (phi) unit, where d is the effective diameter (diameter of the sphere with equivalent volume) of the grain in millimeters. Given that the grain size distribution g(s), where s is the grain size in phi units, is a probability distribution, then In practice, grain size distributions do not extend over the full range of s and are not continuous functions of s. Instead, discretized versions of g(s) with estimates of g(s) in finitesized bins of 0.5ϕ widths are used. Selection of the bin width is largely empirically derived. An increase in width can result in losing information contained in the distribution, whereas a decrease in width can produce an increasingly noisy distribution (a discussion of this dilemma is found in Bowles and McLaren [1985]). Three parameters related to the first 3 central moments of the grain size distribution are of fundamental importance in STA. They are defined here, both for a continuous g(s) and for its discretized approximation with N size classes. The 1st parameter is the mean grain size (m), defined as The 2nd parameter is sorting (s), which is equivalent to the variance of the distribution, defined as Finally, the coefficient of skewness (k) is defined as With the removal of r(s) from g(s), the remaining sediment (a lag) has a new distribution denoted by l(s) (Figure A1) where The function t(s) is defined as a sediment transfer function and is described in exactly the same manner as a grain size probability function except that it is not normalized. It can be thought of as a function that incorporates all sedimentary and dynamic processes that result in initial movement and transport of particular grain sizes. Data from flume experiments show that distributions of transfer functions change from having a high negative skewness to being nearly symmetrical (although still negatively skewed) as the energy of the eroding/transporting process increases. These 2 extremes in the shape of t(s) are termed low-energy and high-energy transfer functions, respectively (Figure A2). The shape of t(s) is also dependent not only on changing energy levels of the process involved in erosion and transport, but also on the initial distribution of the original bed material, g(s) (Figure A1). The coarser g(s) is, the less likely it is to be acted on by a high-energy transfer function. Conversely, the finer g(s) is, the easier it becomes for a high-energy transfer function to operate on it. In other words, the same process can be represented by a high-energy transfer function when acting on fine sediments and by a low-energy transfer function when acting on coarse sediments. The terms high and low energy are, therefore, relative to the distribution of g(s) rather than to the actual process responsible for erosion and transport. Sediment transport model to develop a lag deposit (see the text for a definition of terms). That t(s) appears to be mainly a negatively skewed function results in r(s), the sediment in transport, always becoming finer and more negatively skewed than g(s). The function 1 — t(s) (Figure A1) is, therefore, positively skewed, with the result that l(s), the lag remaining after r(s) has been removed, will always be coarser and more positively skewed than the original source sediment. McLaren and Bowles (1985) provide the mathematical proof for these statements. If t(s) is applied to g(s) many times (i.e., n times, where n is large), then the variance of both g(s) and l(s) will approach zero (i.e., sorting will become better). Depending on the initial distribution of g(s), it is mathematically possible for variance to become greater before eventually decreasing. In reality, an increase in variance in the direction of transport is rarely observed. Given 2 sediments whose distributions are, d1(s) and d2(s), and d2(s) is coarser, better sorted, and more positively skewed than d1(s), it might be possible to infer that d2(s) is a lag of d1(s) and that the 2 distributions were originally the same (Table A1, case A). Consider a sequence of deposits d1(s), d2(s), d3(s), … dn(s) that follows the direction of net sediment transport (Figure A3). Each deposit is derived from its corresponding sediment in transport according to the 3-box model shown in Figure A1. Each dn(s) can be considered a lag of each rn(s). Thus, dn(s) will be coarser, better sorted, and more positively skewed than rn(s). Similarly, each rn(s) is acted on by its corresponding tn(s), with the result that the sediment in transport becomes progressively finer, better sorted, and more negatively skewed. Any 2 sequential deposits (e.g., d1[s] and d2[s]) can be related to each other by a function X(s) (Eqn. 9). As illustrated in Figure A3, d2(s) can also be related to d1(s) by The function X(s) combines the effects of 2 transfer functions, t1(s) and t2(s) (Eqn. 10b). It could also be considered a transfer function in that it provides the statistical relationship between the 2 deposits and it incorporates all of the processes responsible for sediment erosion, transport, and deposition. The distribution of deposit d2(s) will, therefore, change relative to d1(s) according to the shape of X(s), which in turn is derived from the combination of t1(s) and t2(s) as expressed in Equation 10b. It is important to note that X(s) can be derived from the distributions of the deposits d1(s) and d2(s) (Eqn. 10a), and it provides the relative probability of any particular sized grain being eroded from d1, transported, and deposited at d2. With the use of empirically derived t(s) functions, it can be shown that when the energy level of the transporting process decreases in the direction of transport (i.e., t2[si] < t1[si]) and both are low-energy functions, then X(s) is always a negatively skewed distribution (Figure A4). This will result in d2(s) becoming finer, better sorted, and more negatively skewed than d1(s). Therefore, given 2 sediments (d1 and d2), where d2(s) is finer, better sorted, and more negatively skewed than d1(s), it might be possible to infer that the direction of sediment transport is from d1 to d2 (Table A1). Diagram showing the extremes in the shape of transfer functions t(s). In the event that t1(s) is a high-energy function and t2(si) > t1(si) (i.e., energy is decreasing in the direction of transport), the result of Equation 10b will produce a positively skewed X(s) distribution (Figure A4). Therefore, d2(s) will become coarser, better sorted, and more positively skewed than d1(s) in the direction of transport. When these changes occur between 2 deposits, it might be possible to infer that the direction of transport is from d1 to d2 (Table A1). Sediment coarsening along a transport path will be limited by the ability of t1(s) to remain a high-energy function. As the deposits become coarser, it will be less and less likely that the transport processes will maintain high-energy characteristics. With coarsening, the transfer function will eventually revert to its low-energy shape (Figure A2), with the result that the sediment must become finer again. Cases A and C produce identical grain size changes between d1 and d2 (Table A1). Generally, however, the geological interpretation of the environments being sampled will differentiate between the 2 cases. The above model indicates that grain size distributions of sedimentary deposits will change in the direction of net sediment transport according to either case B or case C (Table A1 and Figure A5). Thus, if any 2 samples (d1 and d2) are compared sequentially (i.e., at 2 locations within a sedimentary facies) and their distributions are found to change in the described manner, the direction of net sediment transport can be inferred. Sediment transport model relating deposits in the direction of transport. Summary diagram of t1 and t2 and corresponding X distribution (Eqn. 10b) for cases B and C (Table A1). Changes in grain size descriptors along transport paths. In reality, perfect sequential changes along a transport path as determined by the model and summarized in Figure A5 are rarely observed. This is because of a variety of uncertainties that can be introduced in sampling, in the analytical technique to obtain grain size distributions, in the assumptions of the transport model, and in the statistics used in describing the grain size distributions. These uncertainties are discussed in further detail (see Uncertainties section). One approach that appears to be successful in minimizing uncertainty is a simple statistical method whereby the case (Table A1) is determined among all possible sample pairs contained in a specified sequence. Given a sequence of n samples, (n2 - n)/2 directionally orientated pairs can exhibit a transport trend in one direction and an equal number of pairs in the opposite direction. When any 2 samples are compared with respect to their distributions, the mean can become finer (F) or coarser (C), the sorting can become better (B) or poorer (P), and the skewness can become more positive (+) or more negative (-). These 3 parameters provide 8 possible combinations (Table A2). In STA, if it is postulated that a certain relationship exists among the set of n samples and that this relationship is evidenced by particular changes in sediment size descriptors between pairs of samples, then the number of pairs for which the trend relationship occurs should exceed the number of pairs that would be expected to occur at random by a sufficient amount to state confidently that the trend relationship exists. Suppose that the probability of any trend existing between any pair of samples, if the trend relationships were established randomly, is p. Since there are 8 possible trend relationships among 3 sediment descriptors, and it is assumed that each of these is equally likely to occur, the p value is set to 0.125. To determine whether the number of occurrences of a particular case exceeding the random probability of 0.125, the following 2 hypotheses are tested: H0: p > 0.125 with no preferred direction H1: p < 0.125 and transport occurs in the preferred direction. The Z statistic is considered valid for N < 30 (i.e., a large sample). Thus, for this application, a suite of 8 or 9 samples is the minimum required to evaluate a transport direction. To assess the validity of any transport line, we use the Z score and an additional statistic, the linear correlation coefficient R2, defined as The value of R2 can range from 0 to 1. The definition of R2 is based on the use of a model to relate a dependent parameter y to 1 or more independent parameters (x1, x2, …). In this case, the model used is linear, which can be written as The data (y, x1, x2) are grain size distribution statistics, and the parameters (a0, a1, a2) are from the data with a The dependent parameter is defined as the and the independent parameters are the mean size and the An assumption is that distributions from samples along a transport if in in Figure would to be along a The of the line, which are the would on the of transport or there is no to a linear relationship among the 3 descriptors, there is also no any other of according to the of the relationship for the not to be except from a in of R2 with a high value of the Z score provide in the validity of the transport A low R2 can occur, when the Z score statistic is the of the of many sediment trend from many it appears that low R2 can result when sediments on an assumed transport path are, in reality, from and valid trend statistics the sediments are from a but the sequence is only a approximation of the actual transport and sediments been introduced the transport as in the case of R2, therefore, is and can provide information on the sediment transport The Z score and R2 statistics for each of the sample (Figure used to determine the sediment transport in the are in The McLaren and Bowles (1985) model requires that the grain size distributions of the sampled sediments be described in statistical terms (by the moment measures of mean, sorting, and The basic underlying assumption is that sequential deposits following the of net sediment transport will affect the statistics of the size distributions of the sediments in a predictable way. from this the size distributions of the sediments provide the data with which to for of net sediment transport. in the transport method is used to requires a model of the sediment transport The model is based on the assumption that are more than (i.e., the probability of transport, on a phi as grain size this it can be shown that erosion and of sediments will change the moments of their size distributions in a predictable in the direction of transport. as in transfer functions from sediment data in flume this assumption might not always be the transfer function over only a of the grain before to contained within the assumption is a further assumption that the probability of transport of 1 particular grain size must be independent of the transport of other grain sizes. as whereby the of can the transport of an increase in the of the finer or a decrease in the ability of the process to additional with all that the transport process is a function related to the sediment distribution and the of the erosion Thus, the of the the that the probability of transport must increase over a large range of in the deposits to produce the As and the technique to determine net transport pathways in a variety of and environments has been empirically the use of that an assumption be size distribution of a particular can be the result of sediment from and at It is assumed that is sampled is the of all the sediment derived from an number of The transport direction might not to that for a with a transport In STA, it is assumed that a sample provides a of a sediment facies) with no the to which the sample any that the sample in the for a of many Each might a particular transport and event at a might be from that of the transport as a The can be determined by the in a that a sufficient number of are the sample to the assumption that the sample an of the The distribution of all the the can be compared with a sample on the To provide d1 might be a sample an over whereas d2 of deposition. The trend analysis whether a possible sediment transport relationship or between the 2 deposits exists. might be to transport With between sample locations an of sediments by transport. in further detail in the indicates that to a continuous with samples, the must be sampled at the contained in the This would that for STA, sample could only transport over a in the of or over less than would as or could transport pathways the process of In practice, of a sample spacing must the number of environments likely to affect the the of the sediment and the shape and of the and samples will be by random These can in the the effects of and a sediment and random Sediment trend analysis is, in many to In the information is to a where a is that both the information as as The must be of the information from the noisy In sedimentary the information is the transport direction and the is the sediment The of is to the information from the noisy In the information can be by the from the an approach that in because the of the information and the are both This however, will be in because the of the information the is A large of analytical has been to in These 2 and For in the is as a a the all other than the The then for the to the original the the level of the to the to be the it easier to because of of the It is important to note that is being for is of importance in the would not be sufficient to the In STA, with no to the other of might to the in is with the use of that the level for the range of the If these of the the will the of the and the can be that increase the to The in is not as because the is not and the of the is only In this by can be because the can however, statistical might be to the In a sedimentary can be considered in 2 sample and in a sediment samples can be by One to this would be to many samples in and to produce a method that to this is For there has been on the use of a to sediments because it appears to provide a to many deposits and to the of STA, it has been shown that parameters of the distribution should change in the of erosion or and It that erosion and the parameters of the distribution to in particular when on the shape of the distribution and all however, are that distributions provide information (e.g., and and McLaren whether or is based on the assumption that sediments distributions. a to the sedimentary it is assumed that that do not on the are and are In this if in sediments do to the If do then the process as as a could be more noisy than the original In the approach of STA, the of are because only the data of each sediment grain size distribution are used from which the moments are sediment is over a can be To this of of samples could be used. of the by are, in reality, to in this manner (i.e., the Z as described or the of and These of of samples, which is not If the of the and the information is not the of samples can the information more than it the is to random by a number of samples from the same to a better distribution of that In STA, the assumption is that is and to the trend as the after these might in might provide more and In it is to the from the (i.e., a that over to the which the of the (i.e., the amount of the that is by all of the this is with a which the its the an is to the to the In sediment the rather than but exactly the same analysis can be In this case, the data grain size distributions of the sediment can be represented as a of with a the is a of the sedimentary deposits that how over For 1 would the of changes over a over a that the sample as discussed will set as to can be the in this the to be how is it is In the information is it it would be if not to in a simple analysis of the sedimentary data (e.g., the in the mean grain it is that a transport direction would be To the it is to an assumption as to is being It is then possible to the data to this and whether in a corresponding to the assumption is For a transport process that would produce the of sediments over a To this a can be and all with of less than could be An of the data would then over the The important of this approach in the approach discussed is the use of many sample to the transport direction. This the level of The however, is that it is to because the number of possible transport in a given can be large to The of a transport direction be and can only be to a level and information from other (e.g., In the Z score statistic, however, a transport trend can be determined whereby all possible pairs in a sample sequence are compared with each When either a case B or case C trend random probability within the sample the direction of net sediment transport can be inferred. As the grid spacing must be with the and the number of environments likely to be the shape of the and the statistical of the For it has been found for in sample spacing should not exceed 1 in spacing can be to For (e.g., to determine the transport for a sample spacing will be that a minimum number of samples can be to has also shown that samples should be over of (e.g., and in which the regular grid is to (e.g., and the direction of transport over an many sample this the sediment that should at the sample the with the Z score statistic from the grain size distributions of the and the assumed direction and the the is from the when a and of transport pathways is that or nearly of the samples, the assumption that information transport is contained in the grain size has been the to all the uncertainties that might be It must be that the actual processes responsible for the transport of along the derived pathways are They might in one be in a in the and in still the effects of one of the in the transport is to assess the processes that are likely to The shape of the X distribution is important in the of transport of the along a the of X is Consider a transport N X is then defined as in Equation d2 in one pair is d1 in and of d2 and d1 are with Equation that X is not defined as the of the mean value of d2 by the mean value of d1, the results of the 2 are For of d1, and X are before in there is no to that the of the X distribution should be X(s) can be thought of as a function that the relative probability of each being from d1 and deposited at d2. of X distributions from a large number of environments has shown that basic are when compared with the distributions of the deposits d1(s) and d2(s) (Figure 1. shape of the X distributions d1(s) and The relative probability of being transported, therefore, is a distribution to the actual Thus, the probability of a particular sized grain in the deposit is equal to the probability of its transport and (i.e., there must be a along the transport The bed is and is, therefore, in dynamic An X distribution dynamic can be found in either case B or case C transport, a fine between erosion and when environments are both case B and case C can be along the sample sequence. This is to as a and when this it is that the transport is also a state of dynamic of the 3 distributions are but the of X is finer than the of d1(s) and The of X can be thought of as the size that is the the of the deposits are coarser than these are more deposited than The therefore, must be in a state of net can only be in case B transport. Summary of the given to the of X distributions relative to the d1 and d2 the of the 3 distributions are but the of X is coarser than of d1(s) and This is the of net the size is coarser than the As a the deposits are erosion along the transport erosion can only be in case C transport. of the of d1(s) and d2(s), the X distribution more or less over the size range of the Sediment must fine in the direction of transport however, the bed is no it is a of sediment that with from transport The of is to sediments. X only in fine sediments when the mean grain size is a fine or the X distribution can be sediments are found from their and the of the X distribution that their is no related to size In other words, all an equal probability of being This of the X distribution 1st in the deposits of a and is described in McLaren the occur in fine in which any changes in the distributions are X distributions can be found in both case B and case C R2 is the correlation coefficient derived from the mean, sorting, and skewness of each sample pair a This is a relative of how the samples are related by transport. becoming finer, better sorted, and more negatively skewed in the direction of transport. becoming coarser, better sorted, and more positively skewed in the direction of transport. N is the number of possible pairs in the of X is the number of pairs a particular trend in a direction. Z is the Z score at the level are indicates transport in the direction. indicates transport in the direction. defines the dynamic of the sediments the of samples (i.e., 1 for a
H. Imai, Kirill Morozov, Anderson C. A. Nascimento, Andreas Winter
Bit commitment is an important tool for constructing zero-knowledge proofs and multi-party computation. Unconditionally secure bit commitment can be based, in particular, on noisy channel or correlation where noise considered a valuable resource. Recently, Winter, Nascimento and Imai introduced the concept of commitment capacity, the maximal ratio between the length of a string which the sender commits to and the number of times the noisy channel/correlation is used. They also proved that for any discrete memoryless channel there exists a secure protocol achieving its commitment capacity however, no particular construction was given. Solving their open question, we provide an efficient protocol for achieving the commitment capacity of discrete memoryless systems (noisy channels and correlations).
“It is inconceivable that we should allow so great a possibility for service, for news, for entertainment, for education, to be drowned in advertising chatter.” So spoke Secretary of Commerce Herbert Hoover in 1922 commenting upon the uses to which the new broadcasting medium radio might be put. Today computer-mediated communication similarly is in its early stages of development and much the same thing is being said by early users of the Internet, that global interconnection of networks that offers great promise for the future. The onslaught of commercial activity threatens the vitality and nature of this new mode of communication. Given the momentum behind such commercialization, and the enormous public benefits at risk, the implications of current and future commercialization demand immediate exploration. The way a new communication medium develops and evolves is a complex process that includes technological, social, economic, and regulatory forces. These forces interact, pushing and pulling an innovation into obsolescence or maturity. In the United States, this interaction is strongly influenced by a media philosophy which favors private ownership and commercial exploitation. The development of U.S. media, therefore, is not completely unpredictable, as the process is controlled by profit-driven entities with predictable objectives and desires. Although individual media are unique and their fate not ultimately predetermined, this reliance upon commercialization and privatization helps direct U.S. media down a very specific path. Computer-mediated communication is the latest communication medium to enter this process of development. In the United States, the Internet is no longer the sole domain of an elite group of researchers and scientists. The Internet has attracted great interest in the private sector. It is now widely employed by profit-driven organizations as yet another tool of commerce. The commercial applications of the Internet continue to multiply as corporations and individuals in the pursuit of profits have found new ways to sell, market, promote and advertise goods and services via the Internet. Given the rapid expansion and significance of this recent commercialization, there are some important issues that require immediate exploration: What might be the effect of this growing commercialization? How will it impact the development and direction of the Internet? Can the Internet be protected against the possible negative effects of excessive commercialization? Will computer-mediated communication follow the well-traveled path of previous media or is it somehow inherently or fundamentally different? If overcommercialization refers to a situation where the primary usage of a medium heavily favors the private interests of profit-driven corporations, to what degree will that situation obtain for the Internet? This article addresses these questions and finds both reason for concern and cause for action. If proactive measures are taken fairly soon, many of the negative consequences of over-commercialization may be avoided. This essay concludes with a set of suggested policies and safeguards which would alleviate some of the negative impacts. These safeguards would serve to protect the integrity of the online communications, and help ensure that unprofitable yet important and beneficial uses of this new form of communication do not get “drowned in advertising chatter.” Unlike many nations, the media philosophy in the United States reflects a long standing belief that “the media” and “the government” should remain distinct. Moreover, private ownership of media outlets is reflective of an economic philosophy favoring free enterprise. Although there exists a system of public broadcasting, it is fragile, constantly under attack, and increasingly dependent upon private-sector funding. Thus media in the United States are almost exclusively privately owned and controlled. This reliance upon private ownership and free enterprise is also based upon a belief that competition in the media industries will produce a diversity of resources and information – a marketplace of ideas. This objective is frequently compromised, however, as media organizations tend to eliminate competition through consolidation and mergers to achieve greater economic efficiency. When a medium is young, there are many small, independent players. As it matures, there is increasing consolidation. Historically, such concentration has been followed by government antitrust action aimed at stemming such monopolization or oligopolization. (For example: the Motion Pictures Patent Corporation or “the Trust” case, the Paramount decision, the splitting up of NBC and of the creation of ABC, the Modified Final Judgment and the split up of AT&T.) Recently, concentration of ownership has increased with considerable consolidation within and across media industries. Through horizontal and vertical integration, mergers, joint ventures, and buyouts, media behemoths are growing to unprecedented proportions not merely in the United States but worldwide. Ironically, while consolidation has been on the rise, antitrust intervention has receded. There has been a shift toward encouraging competition on a global rather than a national scale, and toward promoting large, strong and secure U.S.-based companies. As the Internet represents new unconquered territory for these expanding entities, corporate consolidation and government deregulation are important contextual factors that promise to have a major influence on the development of the Internet within the U.S. and elsewhere. Big or small, owners of U.S. media for the most part are permitted to employ whatever strategy they choose to generate revenue. The sale of “space and time” to other companies for advertising purposes has proven to be an effective means of generating generous profit margins for owners. Though not all U.S. media are supported by advertising, many are. Indeed, the line between those few media that are and those that are not has become blurred. Even the book publishing industry has sometimes resorted to an occasional advertising insert. The motion picture industry has also turned to nontraditional ways of supplementing the revenue generated by individual ticket sales. Commercials have made their way into U.S. theaters; on occasion they precede a feature released on a videotape. Indirectly, they appear in the subtle guise of take-home toys accompanying children's fast food. The history of U.S. media illustrates a parallel growth and increasing interdependence of the media and advertising industries. Newspapers in early Colonial America were produced by printers, not journalists, and many even acknowledged the predominance of advertising by including the word in their names. (Hiebert, Ungurait, and Bohn, 1991, pp. 220-221) Even the text of the Declaration of Independence, published in the July 6, 1776 edition of the Pennsylvania Evening Post, appeared alongside advertisements. (Hiebert, Ungurait, and Bohn, 1991, p. 185). The Penny Press in the 1830s, an idea that made newspapers an affordable mass medium, was driven by the then innovative strategy to increase circulation to attract sufficient advertising dollars to replace the money lost through the lower individual sales costs. In the early days of broadcasting, the radio industry relied upon sales of radio receivers as a primary source of revenue. As receiver penetration levels increased, this source of revenue began to dissipate. At the same time, audiences became more discerning, leading to increased production costs. The debate over radio advertising alluded to in the opening passage was short-lived. Advertising quickly became the accepted means of financial support for radio stations and networks. By the time television arrived, broadcasting had been heavily commercialized and the same organizations that had profited handsomely in radio quickly moved into television, bringing with them their established system of commercial support. The pervasive commercial interruption became a staple of broadcasting content. The rhetoric that surrounded the expansion of cable television in the 1970's promised a transformation of television, and was based upon the belief that it would provide an electronic forum that was both diverse and open to the public. Such optimism proved to be unwarranted. Public access channels have sat underfunded, underutilized, and generally unwatched, and the new channel capacity did more to increase the quantity of television than it did to improve the quality. From an advertising perspective, however, cable offered a clear advantage: it delivered targeted and prepackaged audiences. How has this reliance upon advertising revenue affected the direction, development and uses of existing media? Though it would be impossible to answer this question precisely, several broad generalizations can be offered. It should be conceded that advertising has affected U.S. media in several positive ways. For example, the sale of advertising time and space has helped to lower or eliminate the direct cost of information and entertainment to the consumer. By subsidizing costs, advertising has helped make the media more accessible. For example, “free” (advertiser-supported television) is universally available to all who own a television set. The U.S. system of advertising also supports an economic system which is based upon the promotion of competing goods in a marketplace. The money generated by advertising revenues has also benefited the media by enabling the production of high quality content. Ironically, it can also be argued that the increasing reliance upon advertising has lowered the quality of media-delivered information and entertainment in several ways. In a hierarchy of artistic value, media that are dependent upon advertising are placed several notches below those that are not advertising-dependent, i.e., film and literature. With most advertiser-supported media, the emphasis traditionally has been placed on quantity of audience rather than quality of product, and these two do not always go hand-in-hand. In serving two sets of masters, advertisers and consumers, media organizations often have placed their own interest in profits over the public interest. By providing a supportive environment conducive to the insertion of sales pitches, owners repeatedly have compromised the quality of media content. Perhaps the most concise and compelling summation was offered by Gloria Steinem in explaining the decision to hike the individual copy costs of MS. magazine and publish sans advertisements (Steinem, 1990). In sum, the optimism that has surrounded the early years of all U.S. media has been quashed by the negative influence of commercialism. The origins of the Internet have been recorded in many places by many people. (See, for example, Gopher://gopher.isoc.org/11/internet/history) These historical of a that began as a system by and for a group of early as a to and information for and it was not long applications were found for this new of It is to the very time the Internet was to a or commercial as of Internet In two and a advertising their services for the U.S. government the The is a of electronic It is available through the Internet, sometimes with the Internet but merely an on the Internet. Though this commercial activity was not it as a to many users and an followed and there was no immediate onslaught of commercial on the Internet. The of the had for and the early was not Recently, however, the growth of the has an enormous increase in commercial The companies with a and it has also attracted new users to the Internet. of the of the the Internet has As of there were an on the Internet. (For a more commercial applications of the have both and and direct sales are but a few of the more of commercial the commercial applications of the have found the to be and for example, at the future impact of this growing commercialization, to the nature of the Internet Such an will help the degree to which it is or by The of offered by offers a set of the Internet the of this will be Internet is The word “free” has several The most are and and who the as have their access For example, many can their of the source of to for their their are they their that it is not an free of even advertising, is but with costs, it is not free of the information is available for but this will as for their In of and the Internet has been but this is in the of The the most of such Internet is For on the Internet and For many of the same of that in are in might to with who the same of and online as they do in interaction for to the is not available in of or The are and are even more on the Internet is generally For example, networks have helped to and In of many now horizontal over vertical do not and universally they do This is of the of that can at the same thing but at Internet is a means of the of the that the Internet be to access for and the became more in in the form of and Such is now being by a of enormous of is by large, organizations and is by a group of The as a form of but it is also a and it as a is Internet is The Internet, all media, is users even a strong to radio of the current on the of the Internet are great of this is being driven by private interests who commercial on their This will also make the more other media in of the it can therefore, a more for commercial is At the time, there is no of the Internet. not to information on the Internet and there is no government however, an access who and for users its as public concern over such of and as corporations to over this new media the nature of the Internet will be is an Although the Internet a and free in many even those who the word by also on to – a form of As more users and more money the will as in for example, the by and Commerce in the in this In these a and of the Internet in its form and an even of what the Internet will in the future. have been offered to the Internet other have that the Internet is unique it is a applications or places the are This of has helped the for example, is a and are a forum for there are often more than In other is to specific is to channel via the and most of the future activity on the will of this The Internet is fast other media, a where most of the information is by and by The Internet is also as unique it is global in The Internet national providing a enabling users to and and across national This is unique and the for some for the however, it should be that a great of other media television is by and by by many media are global The that the Internet is and by has the of another Such a online communication not as a but as an What lost in the of this is that such within a specific be it the the the and within a specific Public concern over the of illustrates that online are not the When to other media, the Internet is an it is both and existing communication It is part it will many of the of and such a is such also it to it as a new The the way the users the Internet. of the Internet this medium as In the nature of online many users of the Internet have become the of For a more of what online communication it is to the electronic environment the of From their perspective, the Internet, and the offers a new and means of to other media, it has It is It can provide a direct between a and a in ways that the media can of information can be often prepackaged specific or they to the The is not the for and advertising, but it is to some In the the make it an and for advertisers and commercial Given the of users of the Internet to advertising and the for by commercial interests now to online in great there is a for that to be so that the of the might be while the of the new a is to its are a group process of debate based upon and offered by who serve as Thus there some specific with offered for There is a accompanying this for and which may be with There are that to be and protected by The addresses two of the most the possibility that commercial will public and the benefits of a much public and the possibility that commercialization will to an of the of It would be to to advertising and commercial activity on the Internet. Advertising and commercialization should not be to however, to the of The offers not it may be into – some where advertising and commercial is and some where it is not In the we have to set where advertising is or but have been and we have become increasingly of the of advertising into many public and private and ensure that the in the are more For we ensure that electronic do not become the of that have Though few to advertisers that it is an and proven means of a to In where to have their by the however, it is more than a are for that they did not and do not There is over the nature or the of commercial that may be delivered into a of over online clear and to be established electronic to commercial From a perspective, this is as it issues as as both an to the of this private space should be on is for some might to Such an might in help online access for individuals so For example, those who make their available to commercial do so in for however, should not have to to commercial be to action to not to The of has by the that the is to sales have been set by who have their own of and These on an of Internet in and (For more the of Internet at The of such and is not and such as the same their with magazine at is such be a to Such of have some will not it to The of such is fast as a greater of online and the who have established the may be by In the and targeted at may they might be as of the of the public will be in the support to as as to forces with users to for In such would be as and in a public they would on these rather than and the that p. in the and of advertisements in an may the of users for over their own while online The mode of advertising on the the a means of a commercial The information is by them the to so are to upon advertising as a way of free services for Advertising may appear the the the broadcasting sales may appear With more on the users may be with commercial be this The are for and for many advertisements appear is an even more than to where they will be will upon an and ultimately a through a process both users and As advertisers greater resources in online advertising as a to they will more information who is The medium is an for a means of and a of and and provide the most effective and audience tool What would be a for however, would a considerable for Such a for information threatens both and and to be in It is important to the to not information being it will be Perhaps some will to in on the economic of information and it for and online content. and are they will be effective they are a commercialization of online communication will Such to be a are of of government the government has the to As many government are and are Moreover, the of and the issues the of would make it impossible and for a government to all of the not all the would be and under government and to be in a private and entities be established online as a where be Such a with a but widely commercial would help the and by the of Such will help to the of or that will make such to and a activity be by this group and be to the government for action. Such will help make the more The online not be There can be a to may the of the would that is it is more in with the of they would to it would the of the the that there is no on commercialization, and by all users of what is and not with to commercial will make advertisers of the their and help them that commercial is not the of a few but the of of the commercial and they will be will be and we will to the support of access there is a great of competition in the we will a and consolidation in this which will make it to these players. of and should be in by users access to the Internet. This will also help to established established is an important part of the It will be as U.S. mass media, the major for information in U.S. are owned by private companies who have a future of the and who have traditionally those that commercial the Internet, it is to but the that exists it almost impossible to a of important information to the of the the debate over the of such would be public to generate of both the specific as as the behind what a is an information The word to the and refers to an open or where to their goods and to ideas. the existing media are effective at providing a for advertisers to they are effective as open and public Advertising dollars are As some of this money is to online the media may be even more to make to attract those lost dollars or they may more of the economic on individual by increasing their direct costs. to this the of public broadcasting and the and possible of the public and broadcasting as as the to allow the marketplace to and the situation to be than an effective public forum is not within the United States but worldwide. The to be to provide such a global In sum, computer-mediated communication is not a new It is a of as as a new and important means of As a global medium, however, it develops within national and is by and media and economic therefore, of its both within specific national as as on a global This article has on the Internet as it is within the United States of The of a is based upon a and diverse communication system which have the of the Internet as a public by forces. These have the benefits of but such an objective be providing access to the has that is toward There will always be some free information available on the but its may be The more and information will be to and The will and will be for but might to part of the to The of online communication is its of For example, to for sans for the supported and improve the and of the content. Advertising become an in promoting the and development of the but its to beneficial uses and be and its effects become that they are not of online information but also with for How the new will will upon answer the to action to the future in their public interest.
The use of information technologies and services – group-decision-support systems, electronic mail, electronic data interchange (EDI) and electronic information services such as videotex, audiotex and CD-ROM, has received considerable attention in recent research. Of particular current interest is the study of integration of these different services in “networks” such as the Internet and their use in organizations and by individual consumers. In this study, we will argue that the use of telecommunication technologies and services will have its major impact on the coordination mechanisms of how organizations deal with their outside world (that is, the organizational environment). Our main question, therefore, is: How do telecommunication networks and services contribute to the development and maintenance of inter-organizational coordination? This question can be interpreted in two ways. First, what kind of benefits can be expected from the use of telecommunication networks and services for the development and maintenance of inter-organizational coordination? This question will be answered by presenting a theoretical framework in which the concept of networks is used to describe both organizations and telecommunications and to show how these concepts are interrelated. We will argue that the traditional dichotomy between (electronic) markets and hierarchies will be nuanced by offering a third option, the development of network-organizations. Secondly, we ask how telecommunication networks can be developed in order to facilitate the development and maintenance of inter-organizational coordination. We suggest that the way telecommunication networks and services are implemented will have significant impact on the way these networks are used. We will do so by focusing on the participating actors in the implementation phase of network development, and especially the role of system integrators in this process. Case studies have been done in the Dutch sectors of music retail, construction, agriculture and the hotel industry. Relationships between organizations develop on the basis of certain common interests and dependencies. An organization can be defined as a specific solution created by more or less autonomous actors to achieve common goals (Van de Vlist, 1988). Between organizations, relationships are developed for the exchange of goods, resources, information and so on. The inter-organizational relationships are most manifest in commercial transactions, in which goods or services are exchanged from one organization to another. Williamson (1975) has stated that transaction costs will rise when the unpredictability and uncertainty of events increases, and/or when transactions require very specific investments, and/or when the risk of opportunistic behavior of other organizations is high. Williamson argues the higher transaction costs are, the more likely transactions will take place within hierarchically organized firms. That is, when transaction costs are high, firms tend to choose vertical integration in order to control the transaction process. If transaction costs are low, that is; are straightforward, non- repetitive and require no transaction-specific investments, then the market is the optimal choice. Transaction costs thus depend upon the coordination mechanism being used. Markets are mainly coordinated by a price mechanism in which independent actors are searching for the best bargain. Firms are mainly coordinated by supervision in which actors who are involved in power-dependent relationships act according to routines. Powell (1990) has suggested that an alternative coordination structure is emerging: networks. Networks are groups of organizational actors who participate in a general pattern of interaction (Kreps, 1990). Networks can be groups of organizations, but also groups within organizations. Network-organizations stress the interdependence between organizational actors and thus pay a lot of attention to the development and maintenance of (communicative) relationships. At the same time, the different organizational actors have their own particular interests, and can be allied to different network-organizations. Thus, network-relationships can always be characterized by a tension between autonomy and interdependence, between team loyalty and individuality, between competition and cooperation. Traditionally, these networks are considered to be a hybrid form of market and hierarchies but Powell argues that this is “historically inaccurate, overly static, and it detracts from our ability to explain many forms of collaboration that are viable means of exchange.” (Powell, 1990, p. 298). That is, network forms of exchange have completely different modes of coordination that is neither price nor supervision, but mutual interest and interdependence (see Table 1). In line with Powell, we argue that network organizations are not equal to markets, since “central to the conceptualizations of the electronic marketplace is the ability of any buyer or seller to interconnect with a network to offer wares or shop for goods and services. Hence, ubiquity is by definition a prerequisite” (Steinfield, Plummer & Kraut, 1995). Ubiquity is - again, by definition - not a feature of a network organization, since interdependence has to exist; network organizations are built around general patterns of interaction. It is the relationship that counts: A relationship that is dependent on clear communication patterns in order to achieve a mutual understanding. Information and communication can determine whether these autonomous actors (individuals, groups or organizations as a whole) are able to work together. “Communication is defined as a process in which the participants create and share information with one another in order to reach a mutual understanding (….). In other words, communication always implies relationships” (Rogers & Kincaid, 1981). All inter-organizational relationships are characterized both by autonomy and interdependency, self-interest and team-spirit, competition and cooperation. These relationships are often described as value-added partnerships, that is, a set of independent organizations who cooperate to manage (information about) the flow of products and services in the value chain. The partnerships or inter-organizational networks can be either based on horizontal, vertical or symbiotic relationships. Within horizontal relationships, the organizations are one another's competitors. in vertical relationships other in a value and the symbiotic relationships is that the different organizations offer services and products to the The of these partnerships is to achieve - - in to outside this has that structure the of any of the between the of the of products and the of and the of partnerships are, on one the means to any between these different - by means of between and - on the other means to the of the network organization in to organizations not to this In order for network organizations to be - and thus to - depend on relationships based on a network the of to the networks can be as as the of and the system of networks coordination firms and can a for We argue that telecommunication networks and services can the and maintenance of these value-added partnerships facilitate the way organizations as the concept of relationships is in to achieve it is for telecommunication use of any telecommunications implies two the to be to the network from the to and to between actors networks and services can relationships within a value-added communication is or a more exchange of information These services to information by other organizations, or information with of other organizations. a information be to the network of inter-organizational relationships. information be by electronic or will and will and offer a for the of the that can be on the basis of This (see Table impact of telecommunications in of and the of the structure of organizational relationships The are optimal of optimal of and of more goals by products and/or services or by The of the and an of organizations can achieve when telecommunication In information and telecommunications are firms to of coordination and control and thus to inter-organizational relationships, especially and these technologies can be used to create and electronic markets, as can be on the Internet with electronic such as and electronic hierarchies is the with most the main of these technologies in the development and maintenance of network organizations. organizations have more of the in and communication communication is the clear coordination mechanism to these organizations, it is that the use of can these communication of the main of network organizations is that are to and information & as Powell (1990) has information networks is information in the market the price mechanism to information as a and thus to it as as and in a information is not as The be that network organizations the of vertical integration such as control and coordination of actors one is dependent upon and of and with the of independent - 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In this paper we propose a two-round authenticated key agreement protocol using non-interactive zero-knowledge (NIZK) proofs. Essentially, a NIZK proof allows a prover to convince a verifier about the correctness of a statement without interaction. An obvious application of this is in a two-round key agreement protocol where each participant proves non-interactively the knowledge of the private key and a shared secret. Our key agreement protocol is based on this idea and is secure assuming the hardness of the Diffie-Hellman problem (DHP) and another related problem in bilinear maps.
This work addresses the subject of mathematics education at secondary schools from a current and stimulating point of view intimately related to computational science. Cryptology is a captivating way of introducing into the classroom different mathematical subjects such as functions, matrices, modular arithmetic, combinatorics, equations, statistics and proofs, which usually are recognized as difficult for many students. Special attention is paid here to the concepts of proof and verification through the definition of zero-knowledge cryptographic protocols. Many other different cryptographic and cryptanalytic activities (building and breaking ciphers, respectively) and modern cryptographic applications such as secret-sharing protocols are also proposed as resources for motivating mathematics learning and for achieving a significant improvement in student understanding of several algebraic, analytical and statistical concepts.