On a Simple Procedure of Inclusion Probability Proportional to Sizes (IPPS) Sampling

A simple method of inclusion probability proportional to sizes is proposed for samples of size three units. It is shown that the variance of the HORVITZ -THOMPSON estimator based on the proposed sampling scheme is uniformly smaller than that of the customary estimator used in the probability proportional to sizes with replacement sampling. Further, its performance over RAO -HARTLEY -COCHRAN and SAMPFORD sampling schemes has been studied empirically for some of the natural populations.     

Sampling Schemes for Studying Growth of Children

Efficiency of linked cross-sectional scheme has been compared with pure longitudinal schemes for generalised estimation of norm relaxing the condition of constancy of variances. The relevant theory of estimation has been developed and the expression for the optimum estimators alongwith their variances have been derived. The percentage gain in efficiency has been calculated. It has been observed that for higher values of Q, percentage gain in efficiency of proposed scheme over cross-sectional is very high.     

Associated LAH Numbers,Factorial Series Distributions and Unbiased Estimation of a Size Parameter

A finite population consists of kN individuals of N different categories with k individuals each. It is required to estimate the unknown parameter N, the number of different classes in the population. A sequential sampling scheme is considered in which individuals are sampled until a preassigned number of repetitions of already observed categories occur in the sample. Corresponding fixed sample size schemes were considered by Charalambides (1981). The sequential sampling scheme has the advantage of always allowing unbiased estimation of the size parameter N. It is shown that relative to Charalambides' fixed sample size scheme only minor adjustments are required to account for the sequential scheme. In particular, MVU estimators of parametric functions are expressible in terms of the C-numbers introduced by Charalambides.     

Monotonic and non-monotonic single channel open time distributions with two sequential open states

Some conditions under which kinetic schemes including two sequential open states of identical conductance will display a non-monotonic (i.e. with a deficit of short open times and a maximum at t>0) distribution of single channel open times are described theoretically. Neither a closed cyclic scheme nor exclusively irreversible transitions between states are required for non-monotonic distributions. A required condition for the schemes considered here is that all openings are to a state from which closing is not possible. It is the presence of a precursor process to channel closing that produces the non-monotonic distribution. Following each channel opening some time is required for a transition into the second open state from which all closings proceed. Simple schemes of this sort cannot provide the basis of any experimental reports of non-monotonic distributions.     

African Negro

Abstract

Roger L. Stevens is Chairman of the Board of Trustees at the John F. Kennedy Center for the Performing Arts in Washington, D.C., which he championed and funded in its infant stage. Successful in the real estate business (he sold the Empire State Building at a fair profit) Mr. Stevens segued into the theatre, producing such Broadway shows as A Man For All Seasons, Tea and Sympathy, Annie and Deathtrap. He came to Washington as assistant to Lyndon B. Johnson and stayed to build the Kennedy Center and to develop a program which continues to be strong and diverse. Design's Executive Editor Jack Morrison, president of the American Theatre Association, recently interviewed Roger Stevens for our readers.     

Application of Partially Balanced Block Designs to Factorial Experiments

In this paper we present partially balanced block designs with F_p and C_p association schemes. These designs play a great role in the experimental theory since they can be applied to factorial experiments. A particular stress is put on the formulation of association schemes _p and C_p, presentation of exemplary constructions of these designs and their analysis of variance. The presented considerations are abundantly illustrated with examples.     

Fair Scheduling for Input Buffered Switches

Input buffered switch architecture has become attractive for implementing high performance switches for workstation clusters. It is challenging to provide a scheduling technique that is both highly efficient and fair in resource allocation. In this paper, we first introduce an iterative Fair Scheduling (iFS) scheme for input buffered switches that supports fair bandwidth distribution among the flows and achieves asymptotically 100% throughput. We then apply the idea of fair scheduling to switches with multicasting capability and propose an mFS scheme which allocates bandwidth to various flows according to their reservations. We show that mFS produces throughput comparable to the existing schemes while distributing the bandwidth as per the given reservations. Extensive simulation results are presented to validate the effectiveness of our proposed schemes.     

Thesis abstracts

The ecology of Rattus lutreolus lutreolus (Gray) on Nadgee River Flat Daniel Lunney Lichens on mangroves along the east coast of Australia G. Nell Stevens The ecology and evolution of Rattus lutreolus Richard W. Braithwaite     

Selection for uniformity in livestock by exploiting genetic heterogeneity of residual variance

In some situations, it is worthwhile to change not only the mean, but also the variability of traits by selection. Genetic variation in residual variance may be utilised to improve uniformity in livestock populations by selection. The objective was to investigate the effects of genetic parameters, breeding goal, number of progeny per sire and breeding scheme on selection responses in mean and variance when applying index selection. Genetic parameters were obtained from the literature. Economic values for the mean and variance were derived for some standard non-linear profit equations, e.g. for traits with an intermediate optimum. The economic value of variance was in most situations negative, indicating that selection for reduced variance increases profit. Predicted responses in residual variance after one generation of selection were large, in some cases when the number of progeny per sire was at least 50, by more than 10% of the current residual variance. Progeny testing schemes were more efficient than sib-testing schemes in decreasing residual variance. With optimum traits, selection pressure shifts gradually from the mean to the variance when approaching the optimum. Genetic improvement of uniformity is particularly interesting for traits where the current population mean is near an intermediate optimum.     

Variance of Stratified Survey Estimators With Probability of Detection Adjustments

Abstract: Estimates of wildlife population sizes are frequently constructed by combining counts of observed animals from a stratified survey of aerial sampling units with an estimated probability of detecting animals. Unlike traditional stratified survey designs, stratum-specific estimates of population size will be correlated if a common detection model is used to adjust counts for undetected animals in all strata. We illustrate this concept in the context of aerial surveys, considering 2 cases: 1) a single-detection parameter is estimated under the assumption of constant detection probabilities, and 2) a logistic-regression model is used to estimate heterogeneous detection probabilities. Naïve estimates of variance formed by summing stratum-specific estimates of variance may result in significant bias, particularly if there are a large number of strata, if detection probabilities are small, or if estimates of detection probabilities are imprecise. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):837–844; 2008)     

Cryptic dioecy in Mammea (Clusiaceae)

The flowers of Mammea (Clusiaceae) have been reported to be androdioecious, a rare condition in the angiosperms. Pollen from eight taxa from most of the geographic range of the genus was examined to clarify the type of flowers, and thus the breeding system, of the genus. In six of these taxa pollen from both morphologically perfect and male flowers was examined, while in the other two, only pollen from the perfect flowers was used. In all cases pollen from perfect flowers was inaperturate, while that from the staminate flowers was aperturate. Since the inaperturate pollen probably cannot germinate, it is concluded that the perfect flowers are functionally female. Therefore, Mammea has a cryptic dioecious breeding system.The author would like to thank Peter Endress, Michael Hesse, Toby Kellogg, P. Mick Richardson, and Peter F. Stevens for editorial comments and advice. Andrew Doust, Sara Fuentes and Ken Hiser helped on the SEM. Much thanks goes to Peter F. Stevens for his helpful support throughout this project.     

Zeatin-induced one-step in vitro cloning affects the vegetative growth of cranberry (<Emphasis Type="Italic">Vaccinium macrocarpon</Emphasis> Ait.) micropropagules over stem cuttings

Shoot proliferation and rooting of three cranberry (Vaccinium macrocarpon Ait.) cultivars Bergman, Pilgrim, and Stevens were obtained in vitro on a modified nutrient medium containing zeatin following a one-step procedure. Bergman and Stevens differed in terms of shoot height, leaf number per shoot, rooting frequency, root number per explant, and root length; this was manifested with various concentrations of zeatin. Shoots proliferated and roots developed best when nodal segments were cultured in the medium supplemented with very low concentration of zeatin (2–4 μM). Such zeatin-induced tissue culture (TC) shoots of Bergman, Pilgrim, and Stevens were rooted ex vitro and compared with those propagated by conventional softwood cuttings (SC) for growth and morphology over four growth seasons. Significant interactions for leaf number per upright were observed among the treatments. The cultivars differed in terms of runner number per plant, upright length, number of leaves per upright, and shoot vigor. The propagation method had an effect on morphology of cranberry plants. The TC plants produced more runners and uprights with more leaves per upright than the conventional cuttings. This increase in vegetative growth of in vitro-derived plants over stem cuttings varied among genotypes. In vitro culture on zeatin-containing nutrient medium apparently induces the juvenile branching characteristics that favored enhanced vegetative growth with more shoots and leaf production.     

Genetic integrity and individual identification-based population size estimate of the endangered long-tailed goral,Naemorhedus caudatus from Seoraksan National Park in South Korea,based on a non-invasive genetic approach

ABSTRACT

The long-tailed goral (also called the Amur goral) Naemorhedus caudatus (subfamily Caprinae), a vulnerable and protected species designated by IUCN and CITES, has sharply been declining in the population size and is now becoming critically endangered in South Korea. This species has been conserved as a natural monument by the Korean Cultural Heritage Administration since 1968. In this study, using 78 fecal DNA samples with a non-invasive genetic approach, we assessed the genetic integrity and individual identification-based population size for the goral population from Seoraksan National Park representing the largest wild population in Korea. Using the successfully isolated 38 fecal DNA, phylogeographic and population genetic analyses were performed with mitochondrial DNA control region (CR) sequences and nine microsatellite loci. We found seven CR haplotypes, of which five were unique to the Seoraksan population, considering previously determined haplotypes in Korean populations. The Seoraksan population showed higher haplotype diversity (0.777?±?0.062) and mean number of alleles (4.67?±?1.563) relative to southern populations in Korea reported from previous studies, with no signal of a population bottleneck. Microsatellite-based individual identification estimate based on probability of identity (PID) indicated a population size of ≥30 in this population. Altogether, we suggest that for future management efforts of this species in the Seoraksan National Park, conserving its genetic integrity as an ‘endemic’ lineage, and curbing a decrease in its number through mitigating habitat destruction might be key to secure the population for the long term.     

Aggregated Multicast – A Comparative Study

Though IP multicast is resource efficient in delivering data to a group of members simultaneously, it suffers from scalability problem with the number of concurrently active multicast groups because it requires a router to keep forwarding state for every multicast tree passing through it. To solve this state scalability problem, we proposed a scheme, called aggregated multicast. The key idea is that multiple groups are forced to share a single delivery tree. In our earlier work, we introduced the basic concept of aggregated multicast and presented some initial results to show that multicast state can be reduced. In this paper, we develop a more quantitative assessment of the cost/benefit trade-offs. We propose an algorithm to assign multicast groups to delivery trees with controllable cost and introduce metrics to measure multicast state and tree management overhead for multicast schemes. We then compare aggregated multicast with conventional multicast schemes, such as source specific tree scheme and shared tree scheme. Our extensive simulations show that aggregated multicast can achieve significant routing state and tree management overhead reduction while containing the expense of extra resources (bandwidth waste and tunnelling overhead). We conclude that aggregated multicast is a very cost-effective and promising direction for scalable transit domain multicast provisioning.     

Computer simulation of family selection schemes suitable for kale (Brassica oleracea L.), involving half-sib,full-sib and selfed families

Summary Three recurrent selection schemes suitable for kale (Brassica oleracea L.), involving half-sib (HS), full-sib (FS) and selfed (S) families, were compared by computer simulation. All combinations of 6, 12 and 24 families selected, out of 120 and 240 assessed, were investigated for a range of genetical models. Selection was simulated for 20 generations from an initial allele frequency of 0.05 and for 16 generations from an initial frequency of 0.20. With an initial frequency of 0.05 there was a serious loss of desired alleles ranging from 0.31 out of 20 for the HS scheme with 24 out of 240 families selected to 9.19 for the S scheme with 6 out of 120 families selected. It was concluded that if as many as 20 cultivars were included in the initial population the selection scheme should be chosen to minimise the loss. With an initial frequency of 0.20 there were no losses with 12 and 24 families selected in the HS and FS schemes respectively, and the highest loss was 2.88 for the S scheme with 6 out of 120 families selected. It was concluded that if as few as five cultivars were included in the initial population a compromise between the initial response to selection and the loss of desired alleles should be sought. Selecting 6, 12 and 24 families for the HS, FS and S schemes respectively, resulted in average relative responses per generation of 2.28, 2.74 and 2.76, respectively for the first five generations, and losses of 0.22, 0.13 and 0.35, respectively after 16 generations. Practical considerations favour the FS scheme over the S scheme.     

Cryptanalysis and Improvement of a Biometric-Based Multi-Server Authentication and Key Agreement Scheme

With the security requirements of networks, biometrics authenticated schemes which are applied in the multi-server environment come to be more crucial and widely deployed. In this paper, we propose a novel biometric-based multi-server authentication and key agreement scheme which is based on the cryptanalysis of Mishra et al.’s scheme. The informal and formal security analysis of our scheme are given, which demonstrate that our scheme satisfies the desirable security requirements. The presented scheme provides a variety of significant functionalities, in which some features are not considered in the most of existing authentication schemes, such as, user revocation or re-registration and biometric information protection. Compared with several related schemes, our scheme has more secure properties and lower computation cost. It is obviously more appropriate for practical applications in the remote distributed networks.     

Generalized gradient schemes for the measurement of two-dimensional image motion

This paper describes a procedure for recovering the global velocity of an image by incorporating spatial filtering, and, optionally, temporal filtering, into a scheme that employs a generalized version of the gradient algorithm of motion detection. Motion within a patch is analysed by six parallel channels, each incorporating a different spatiotemporal filter. Advantageous features of this scheme are: (a) global velocity is derived directly, without first computing local velocity at a number of image locations; (b) the filters compute first derivatives rather than second derivatives, making the scheme potentially more resistant to noise than certain other schemes; (c) two of the six filters can be chosen almost completely arbitrarily, and can therefore be tailored to maximize signal reliability, and (d) the measurement of velocity can be made as local or as global as desired by altering the size of the patch that is viewed by the filters. An analogous scheme is derived for the measurement of rotation, as well as expansion or contraction of the image.     

Assessing the impact of Entry Level Stewardship on lowland farmland birds in England

Agri‐environment schemes (AES) are central to the conservation of Europe’s farmland biodiversity. The UK Government’s Public Service Agreement target seeks to reverse the decline of farmland birds in England by 2020 through the use of AES. The Entry Level Stewardship (ELS) scheme, introduced in 2005, is the first non‐competitive, broad‐uptake stewardship scheme designed to deliver simple but effective environmental management on farms throughout England. Approximately 5 million hectares of farmland are currently entered into Environmental Stewardship (ES) agreements, and given the scale of this investment it is important to verify the efficacy of ELS as a mechanism for delivering biodiversity benefits. We used spatially referenced ES agreement data to assess the influence of specific management options and combinations of options on farmland bird population changes between 2005 and 2008 derived from standardized surveys carried out on over 2000 lowland farmland 1‐km squares in England. The results showed only limited evidence for short‐term effects of ES. Only Corn Bunting Emberiza calandra and Common Starling Sturnus vulgaris showed some landscape‐specific positive associations with area under ELS management. There was also limited evidence for positive associations between specific management options and the population changes of the species at which they were aimed. The current pattern of option uptake may be limiting benefits of ELS, with boundary management accounting for over 50% of scheme compensation value. However, the time required for option maturation and the time lags in bird population responses to environmental change mean that it is too early to reach definitive conclusions about the success or failure of the scheme. The findings of this study will assist in the development of ELS by feeding into the 5‐year review scheduled for 2010 and have implications for the development of similar schemes elsewhere in Europe.     

Effective stomatal and boundary-layer resistances of heterogeneous surfaces

In nature surfaces are rarely uniform, so terms such as ‘surface’, ‘stomatal’ or ‘canopy’ resistance usually indicate some kind of average over a population of sub-areas, each with its own separate resistance. Questions then arise as to how gross measurements of these resistances should be interpreted in terms of the components, or how components should be aggregated into representative single values. Aggregation schemes have been published by Raupach (1991, Vegetatio 91, 105–120) and Lhomme (1992, Agriculture and Forest Meteorology 61, 11–21), but these are different for reasons that were not explained. This paper develops the idea that averaging schemes should be designed to serve particular purposes, and that they can be varied to suit these purposes. It is shown that the ‘effective’ resistances defined by Raupach and Lhomme preserve different quantities. A further averaging scheme is developed which preserves both correct transpiration rate and CO₂ flux when used in the Penman-Monteith equation and an equation describing assimilation. All of these schemes are fairly complex, so the work provides a warning against naive use of effective variables.     

Indexing European bird population trends using results of national monitoring schemes: a trial of a new method

Many European countries have annual breeding bird monitoring schemes based on nationwide samples; most are in northern and western Europe. We have developed a method to produce yearly population indices of bird species across countries by combining the results of existing national schemes. The method takes into account the differences in population sizes per country, as well as the differences in field methods, and the numbers of sites and years covered by the national schemes. In order to test the method, we collected raw data from a number of countries and applied an index method to produce scheme results per country. Data were collected for five farmland species (Lapwing Vanellus vanellus, Linnet Carduelis cannabina, Skylark Alauda arvensis, Whitethroat Sylvia communis and Yellowhammer Emberiza citrinella), from seven countries (UK, Netherlands, Denmark, Germany, Finland, Latvia and Estonia) for a 20-year period (1978–97). The trial demonstrated that it was possible to combine national indices to provide supra-national yearly totals and their standard errors; the results were similar to those produced when the raw data were used. Thus, yearly European indices can be produced by exchanging only limited amounts of information, that is the national yearly indices of each species or, preferably, the yearly population numbers and their standard errors. At a European scale, the populations of the five species selected have changed considerably. In western Europe (UK, Netherlands, Denmark and former West Germany combined), Linnet, Skylark and Yellowhammer have declined and Whitethroat has increased. Most changes occurred during the first ten-year period (1978–88). The changes in eastern Europe (the remaining countries) were less clear, in part because the statistical power of the national schemes is as yet limited.