Quantum Attack-Resistent Certificateless Multi-Receiver Signcryption Scheme

The existing certificateless signcryption schemes were designed mainly based on the traditional public key cryptography, in which the security relies on the hard problems, such as factor decomposition and discrete logarithm. However, these problems will be easily solved by the quantum computing. So the existing certificateless signcryption schemes are vulnerable to the quantum attack. Multivariate public key cryptography (MPKC), which can resist the quantum attack, is one of the alternative solutions to guarantee the security of communications in the post-quantum age. Motivated by these concerns, we proposed a new construction of the certificateless multi-receiver signcryption scheme (CLMSC) based on MPKC. The new scheme inherits the security of MPKC, which can withstand the quantum attack. Multivariate quadratic polynomial operations, which have lower computation complexity than bilinear pairing operations, are employed in signcrypting a message for a certain number of receivers in our scheme. Security analysis shows that our scheme is a secure MPKC-based scheme. We proved its security under the hardness of the Multivariate Quadratic (MQ) problem and its unforgeability under the Isomorphism of Polynomials (IP) assumption in the random oracle model. The analysis results show that our scheme also has the security properties of non-repudiation, perfect forward secrecy, perfect backward secrecy and public verifiability. Compared with the existing schemes in terms of computation complexity and ciphertext length, our scheme is more efficient, which makes it suitable for terminals with low computation capacity like smart cards.     

Application of Central Upwind Scheme for Solving Special Relativistic Hydrodynamic Equations

The accurate modeling of various features in high energy astrophysical scenarios requires the solution of the Einstein equations together with those of special relativistic hydrodynamics (SRHD). Such models are more complicated than the non-relativistic ones due to the nonlinear relations between the conserved and state variables. A high-resolution shock-capturing central upwind scheme is implemented to solve the given set of equations. The proposed technique uses the precise information of local propagation speeds to avoid the excessive numerical diffusion. The second order accuracy of the scheme is obtained with the use of MUSCL-type initial reconstruction and Runge-Kutta time stepping method. After a discussion of the equations solved and of the techniques employed, a series of one and two-dimensional test problems are carried out. To validate the method and assess its accuracy, the staggered central and the kinetic flux-vector splitting schemes are also applied to the same model. The scheme is robust and efficient. Its results are comparable to those obtained from the sophisticated algorithms, even in the case of highly relativistic two-dimensional test problems.     

The Yorkshire slide exchange external quality assessment (EQA) scheme

A slide circulation scheme measuring cervical screening performance of individual cytologists in 15 laboratories in Yorkshire Regional Health Authority is described. The advantages and disadvantages are compared with the current National Proficiency Testing (NPT) scheme. The results indicate that a slide circulation scheme can be successfully used in cervical cytology external quality assessment (EQA). Levels of participation are better than those currently achieved by regional variations of the NPT scheme, and the use of laboratory consensus in the selection of scoring slides appears to be no less valid than the use of a pre‐selected slide pool assembled by an expert panel. The volume of data accumulated in one round is considerably greater than that achieved by proficiency testing and the educational value is regarded as high. However, the scheme is very time consuming for participants and consequently expensive for laboratories. The lack of external supervision increases the risk of unfair practices within individual laboratories. Because of these problems, Yorkshire has now switched to an NPT scheme.     

Error-tolerant pooling designs with inhibitors.

Pooling designs are used in clone library screening to efficiently distinguish positive clones from negative clones. Mathematically, a pooling design is just a nonadaptive group testing scheme which has been extensively studied in the literature. In some applications, there is a third category of clones called "inhibitors" whose effect is to neutralize positives. Specifically, the presence of an inhibitor in a pool dictates a negative outcome even though positives are present. Sequential group testing schemes, which can be modified to three-stage schemes, have been proposed for the inhibitor model, but it is unknown whether a pooling design (a one-stage scheme) exists. Another open question raised in the literature is whether the inhibitor model can treat unreliable pool outcomes. In this paper, we answer both open problems by giving a pooling design, as well as a two-stage scheme, for the inhibitor model with unreliable outcomes. The number of pools required by our schemes are quite comparable to the three-stage scheme.     

THE PRACTICAL ASPECTS OF IMPLEMENTING A CONTROLLED BURNING SCHEME IN THE KIDEPO VALLEY NATIONAL PARK

A controlled burning scheme, in conjunction with experimental plots, was necessary in order to investigate the effects of fire on tree regeneration in an area which otherwise suffers frequent uncontrolled fires and where an important tree species, Acacia gerrardii, was failing to regenerate. The proposed programme, the methods of putting in firebreaks and carrying out burns, and the first year's results, are described. Although during this first year of operation the scheme was only partially successful in excluding uncontrolled fires, valuable experience was gained regarding various aspects and problems associated with the operation of such a scheme.     

Stochastic multitype epidemics in a community of households: estimation and form of optimal vaccination schemes

This paper treats a stochastic model for an SIR (susceptible-->infective-->removed) multitype household epidemic. The community is assumed to be closed, individuals are of different types and each individual belongs to a household. Previously obtained probabilistic and inferential results for the model are used to derive the optimal vaccination scheme. By this is meant the scheme that vaccinates the fewest among all vaccination schemes that reduce the threshold parameter below 1. This is done for the situation where all model parameters are known and also for the case where parameters are estimated from an outbreak in the community prior to vaccination. It is shown that the algorithm which chooses vaccines sequentially, at each step selecting the individual which reduces the threshold parameter the most, is not in general an optimal scheme. As a consequence, explicit characterisation of the optimal scheme is only possible in certain special cases. Two different types of vaccine responses, leaky and all-or-nothing, are considered and compared for the problems mentioned above. The methods are illustrated with some numerical examples.     

Genetic algorithm with alphabet optimization

 In recent years the genetic algorithm (GA) was used successfully to solve many optimization problems. One of the most difficult questions of applying GA to a particular problem is that of coding. In this paper a scheme is derived to optimize one aspect of the coding in an automatic fashion. This is done by using a high cardinality alphabet and optimizing the meaning of the letters. The scheme is especially well suited in cases where a number of similar problems need to be solved. The use of the scheme is demonstrated with such a group of problems: the simplified problem of navigating a ‘robot’ in a ‘room.’ It is shown that for the sample problem family the proposed algorithm is superior to the canonical GA. Received: 26 August 1994/Accepted in revised form: 13 January 1995     

Genetically programmed cell death (apoptosis)

Extensively and successfully studied problems of programmed cell death are considered. Recent evidence on apoptosis genes is presented, including the bcl-2 family and other genes with similar functions. A scheme of pathways of the main apoptosis mechanism is constructed. Examples of associations of apoptosis and diseases are presented in a special section.     

P-16DEFAULT FROM CYTOLOGICAL SURVEILLANCE OF LOW-GRADE SMEARS: LEVELS OF DEFAULT AND CHARACTERISTICS OF DEFAULTERS IN THE TRIAL OF MANAGEMENT OF BORDERLINE AND OTHER LOW-GRADE ABNORMAL SMEARS (TOMBOLA)

The problems encountered with a glass slide circulation are legion but timely circulation is a major problem and is an inherent deficiency of our Non-gynaecological EQA scheme. This applies not only to consultants but also to specialist registrars (SpRs) and technical staff that are not formally included in the circulation list. In 2005 only 7 technical staff and 4 out of 47 SpRs took part on a formal basis, their participation being dependant on access to slides during their cytology attachment. The results for the 2005 circulation have been analysed and despite the small numbers of participating technical staff and SpRs their answers concur with the consultant body. To address the issues of timeliness and circulation problems a pilot teaching set has been developed by SlidePath into a virtual microscope web based circulation and sent to all SpRs in our region. They have recorded their answers and been given immediate access to the consensus consultant opinion with illustrations of follow up histology. A questionnaire was completed to evaluate the scheme. The facility of immediate feedback of consultant consensus is particularly pertinent to the educational element of the scheme and use of virtual microscopy addresses the issue of timely circulation. If further funding was made available technical staff could also be given the opportunity to try this web-based circulation.     

P‐15COMPARISON OF RESULTS FOR A NON‐GYNAECOLOGICAL CYTOLOGY EQA SCHEME

The problems encountered with a glass slide circulation are legion but timely circulation is a major problem and is an inherent deficiency of our Non‐gynaecological EQA scheme. This applies not only to consultants but also to specialist registrars (SpRs) and technical staff that are not formally included in the circulation list. In 2005 only 7 technical staff and 4 out of 47 SpRs took part on a formal basis, their participation being dependant on access to slides during their cytology attachment. The results for the 2005 circulation have been analysed and despite the small numbers of participating technical staff and SpRs their answers concur with the consultant body. To address the issues of timeliness and circulation problems a pilot teaching set has been developed by SlidePath into a virtual microscope web based circulation and sent to all SpRs in our region. They have recorded their answers and been given immediate access to the consensus consultant opinion with illustrations of follow up histology. A questionnaire was completed to evaluate the scheme. The facility of immediate feedback of consultant consensus is particularly pertinent to the educational element of the scheme and use of virtual microscopy addresses the issue of timely circulation. If further funding was made available technical staff could also be given the opportunity to try this web‐based circulation.     

Apoptosis: Genetically Programmed Cell Death

Extensively and successfully studied problems of programmed cell death are considered. Recent evidence on apoptosis genes is presented, including the bcl-2 family and other genes with similar functions. A scheme of pathways of the main apoptosis mechanism is constructed. Examples of associations of apoptosis and diseases are presented in a special section.     

Cervical cytology EQA – the Northern experience

The experience of the Northern region using the 1995 draft National Gynaecological Cervical Cytology External Quality Assurance (EQA) Scheme is given. Over three rounds, 390 staff reporting Cervical Cytology took part, and using a cumulative non-numeric marking scheme, five participants were deemed "unacceptable" at the end of three rounds. A total of 3450 responses were given to the 40 test slides used, with an overall false-positive rate of 5.9% and a false-negative rate of 1.4%. Grading was assessed for pathologists, and many appeared to perform badly by accumulating discrepancies for non-clinically-significant grading differences. The problems of slide selection/staining and grading consistency/accuracy are highlighted. This EQA scheme serves its dual function of education and identifying poor performance. It must be seen as a viable EQA scheme, although other options must be considered, given advances in technology.     

Implicit-explicit methods for reaction-diffusion problems in pattern formation

Reaction-diffusion mechanisms have been used to explain pattern formation in developmental biology and in experimental chemical systems. To approximate the corresponding spatially discretized models, an explicit scheme can be used for the reaction term and an implicit scheme for the diffusion term. Such implicit-explicit (IMEX) schemes have been widely used, especially in conjunction with spectral methods in fluid flow problems.In this work, we analyze the performance of several of the best known linear multistep IMEX schemes for reaction-diffusion problems in pattern formation. For the linearized two chemical system, the growth properties exhibited by IMEX schemes are examined. Schemes which accurately represent the growth of the linearized problem for large time steps are identified. Numerical experiments show that first order accurate schemes, as well as schemes which produce only a weak decay of high frequency spatial error may yield plausible results which are nonetheless qualitatively incorrect. For such schemes, computations using refinements in the time step are likely to produce essentially the same (erroneous) results. Higher order schemes which produce a strong decay of high frequency errors are proposed instead.Our findings are demonstrated on several examples.The work of the author was partially supported by an NSERC Postgraduate Scholarship     

IN DEFENCE OF PRIORITY REVIEW VOUCHERS

Infectious and parasitic diseases cause enormous health problems in the developing world whereas they leave the developed one relatively unscathed. Research and development (R&D) of drugs for diseases that mainly affect people in developing countries is limited. The problem that relatively few drugs are available for diseases that cause an enormous burden of disease in the developing world is called the 'availability problem'. In recent years, the availability problem has received quite a bit of attention. A number of proposals have been fielded as to how this problem might be minimized. Wild-card patent extensions, advance market commitments, cash prizes and the Health Impact Fund are prominent examples of such proposals. These proposals can be thought of as pull-mechanisms for R&D of drugs for neglected diseases. What has been coined a 'priority review voucher' is another pull-mechanism. This paper is a critical discussion of this pull-mechanism. First, the original priority review voucher scheme, as proposed by Ridley et al. (2006), is described. A number of objections to this scheme are thereafter presented. A few amendments to the original scheme are then suggested, and it is argued that with these amendments in place, the priority review voucher scheme constitutes an attractive way of stimulating R&D of drugs for neglected diseases.     

Numerical Solution to Generalized Burgers'-Fisher Equation Using Exp-Function Method Hybridized with Heuristic Computation

In this paper, a new heuristic scheme for the approximate solution of the generalized Burgers''-Fisher equation is proposed. The scheme is based on the hybridization of Exp-function method with nature inspired algorithm. The given nonlinear partial differential equation (NPDE) through substitution is converted into a nonlinear ordinary differential equation (NODE). The travelling wave solution is approximated by the Exp-function method with unknown parameters. The unknown parameters are estimated by transforming the NODE into an equivalent global error minimization problem by using a fitness function. The popular genetic algorithm (GA) is used to solve the minimization problem, and to achieve the unknown parameters. The proposed scheme is successfully implemented to solve the generalized Burgers''-Fisher equation. The comparison of numerical results with the exact solutions, and the solutions obtained using some traditional methods, including adomian decomposition method (ADM), homotopy perturbation method (HPM), and optimal homotopy asymptotic method (OHAM), show that the suggested scheme is fairly accurate and viable for solving such problems.     

The identification of nonlinear biological systems: LNL cascade models

Systems that can be represented by a cascade of a dynamic linear (L), a static nonlinear (N) and a dynamic linear (L) subsystem are considered. Various identification schemes that have been proposed for these LNL systems are critically reviewed with reference to the special problems that arise in the identification of nonlinear biological systems. A simulated LNL system is identified from limited duration input-output data using an iterative identification scheme.     

Efficient push-based packet scheduling for Peer-to-Peer live streaming

Content scheduling is a key component of Peer-to-Peer (P2P) networks. The problem is how to schedule the content delivery to the children peers with multiple parents to improve the overall performance of the systems. The challenge is to design a scheme with low delay and low bandwidth utilization. Most of recent works propose pull-based schemes, whose processes for periodically advertising and requesting on per-packet basic lead to long delay. However, long playback delay is undesirable for live streaming and TV shows. In this paper, we formulate the scheduling problems as to minimize the playback delay due to scheduling. To solve the problem and address the packet redundancy and disorder packet arrival issues, we propose a novel push-based scheme. In our scheme, parents push packets to their children in a given interval pattern as soon as the packets are received, and children feed back network condition changes with an interval pattern when necessary. The scheme eliminates the processes of buffer advertising and packet requesting, and reduces control traffic, delivery delay and playback delay much more than the pull-based schemes. We provide an efficient scheduling algorithm and its implementation for simulation. The simulation results show that our scheme outperforms other pull-based schemes significantly.     

THE PRACTICAL ASPECTS OF IMPLEMENTING A CONTROLLED BURNING SCHEME IN THE KIDEPO VALLEY NATIONAL PARK (SECOND YEAR OF OPERATION)

A controlled burning scheme, in conjunction with experimental plots, was necessary in order to investigate the effects of fire on tree regeneration in an area which otherwise suffers frequent uncontrolled fires and where an important tree species, Acacia gerrardii Benth.var. gerrardii, was failing to regenerate. The second year's results are described. The scheme was not successful in excluding uncontrolled fires. However, further experience, indicating yet more problems, was gained.     

Application of Different Variants of the BEM in Numerical Modeling of Bioheat Transfer Problems

Heat transfer processes proceeding in the living organisms are described by the different mathematical models. In particular, the typical continuous model of bioheat transfer bases on the most popular Pennes equation, but the Cattaneo-Vernotte equation and the dual phase lag equation are also used. It should be pointed out that in parallel are also examined the vascular models, and then for the large blood vessels and tissue domain the energy equations are formulated separately. In the paper the different variants of the boundary element method as a tool of numerical solution of bioheat transfer problems are discussed. For the steady state problems and the vascular models the classical BEM algorithm and also the multiple reciprocity BEM are presented. For the transient problems connected with the heating of tissue, the various tissue models are considered for which the 1st scheme of the BEM, the BEM using discretization in time and the general BEM are applied. Examples of computations illustrate the possibilities of practical applications of boundary element method in the scope of bioheat transfer problems.     

The identification of nonlinear biological systems: Wiener and Hammerstein cascade models

Systems that can be represented by a cascade of a dynamic linear subsystem preceded (Hammerstein cascade model) or followed (Wiener cascade model) by a static nonlinearity are considered. Various identification schemes that have been proposed for the Hammerstein and Wiener systems are critically reviewed with reference to the special problems that arise in the identification of nonlinear biological systems. Examples of Wiener and Hammerstein systems are identified from limited duration input-output data using an iterative identification scheme.