Variance to mean ratio and the spatial distribution of animals

Summary Biological and statistical aspects of the application of variance to mean ratio to describe spatial distribution of animals are discussed. It is shown that the parameterb inTaylor's power laws ²=a m ^b shows intra-specific variation depending on the distribution of the constituent units of the population.a andb are only parameters of a very empirical way of describing the relation between variance and mean, which itself is an indicator for spatial distribution. Hence,a andb depend on the distribution behaviour of the animals, and not vice versa.Acknowledgments: The work was developed whilst I was at the Department of Entomology, University of Nairobi. I am grateful to ProfessorT. R. Odhiambo for his interest. I thank the referee for comments.     

Occurrence of biopterin in the wings ofMorpho butterflies

A blue fluorescent compound was isolated fromMorpho butterfly wings. Based on thin layer chromatographic, UV and CD-spectrophotometric and HPLC analyses, the blue fluorescent compound was identified as L-erythro biopterin. Biopterin is a major component of blue fluorescent pteridines in bothM. sulkowskyi andM. adonis. Pterin and isoxanthopterin can also be detected as minor components in these species. This paper is the first to report the presence of biopterin in butterfly wings.     

Testing and forecasting the degree of integration in the US inflation rate

In this article we model the log of the US inflation rate by means of fractionally integrated processes. We use the tests of Robinson (1994) for testing this type of hypothesis, which include, as particular cases, the I(0) and I(1) specifications, and which also, unusually, have standard null and local limit distributions. A model selection criterion is established to determine which may be the best model specification of the series, and the forecasting properties of the selected models are also examined. The results vary substantially depending on how we specify the disturbances. Thus, if they are white noise, the series is I(d) with d fluctuating around 0.25; however, imposing autoregressive disturbances, the log of the US inflation rate seems to be anti‐persistent, with an order of integration smaller than zero. Looking at the forecasting properties, those models based on autocorrelated disturbances (with d < 0) predict better over a short horizon, while those based on white noise disturbances (with d > 0) seem to predict better over longer periods of time. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of ACTH on the zona reticularis of the rat adrenal cortex: An ultrastructural stereologic study

Summary The effects of ACTH on the rat adrenalzona reticularis were investigated by stereologic methods. It was found that thezona reticularis cell responsiveness to ACTH is similar to that of thezona fasciculata elements. This excludes that thezona reticularis of the adult rat can only function as the site of destruction of worn-out elements migrating from the adrenal outer zones.Acknowledgment. We wish to thank Mr.G. Gottardo for his skilled technical assistance. This work was partly supported by a contract with the CNR No. C.T.73.00663.04.     

An immune response-dependent mechanism for the vertical transmission of an entomopathogen

Summary An exceptionally efficient mechanism for the vertical transmission of a parasitic gregarine is dependent on the insect host's immune response. Gametocysts ofAscogregarina chagasi on the genital accessory glands of adult female sand flies (Lutzomyia longipalpis) become encapsulated through hemocyte-mediated immune reactions. Oocysts ofA. chagasi, ejected into the lumen of the glands owing to pressure exerted by this capsule, become glued to eggshells and are subsequently ingested by larvae. InL. longipalpis with an experimentally suppressed encapsulation reaction, fewer accessory glands contained oocysts ofA. chagasi.     

Ammotragus lervia: Progenitor of the domesticated sheep or specialized offshoot of caprine evolution?

Summary Data on haemoglobin do not support suggestions that the aoudadAmmotragus lervia is close to a hypothetical ancestor to the genusOvis in general or to the domesticated sheepOvis aries in particular.Ammotragus haemoglobin is more like that from the domestic goatCapra hircus than that from the domestic sheepOvis aries, but also shows some unique characteristics, perhaps more specialized than primitive.     

Gonyauline: A novel endogenous substance shortening the period of the circadian clock of a unicellular alga

Summary The circadian clock in the unicellular algaGonyaulax polyedra is accelerated by a substance in extracts from the cells themselves. The extracts have been fractionated using the circadian rhythm of bioluminescence as bioassay. The active substance, termed gonyauline, has been isolated and characterized as a novel low molecular weight cyclopropanecarboxylic acid (S-methyl-cis-2-(methylthio) cyclopropanecarboxylic acid). Synthetic gonyauline has a similar shortening effect on the period of the circadian clock.     

Forecasting for the generation of trading signals in financial markets

In this paper we show that optimal trading results can be achieved if we can forecast a key summary statistic of future prices. Consider the following optimization problem. Let the return r_i (over time i=1, 2, ..., n) for the ith day be given and the investor has to make investment decision d_i on the ith day with d_i=1 representing a ‘long' position and d_i=0 a ‘neutral' position. The investment return is given by r=Σⁿ_i=1r_id_i−cΣⁿ⁺¹_i=1∣d_i−d_i−1∣, where c is the transaction cost. The mathematical programming problem of choosing d₁, ..., d_n to maximize r under a given transaction cost c is shown to have an analytic solution, which is a function of a key summary statistic called the largest change before reversal. The largest change before reversal is recommended to be used as an output in a neural network for the generation of trading signals. When neural network forecasting is applied to a dataset of Hang Seng Index Futures Contract traded in Hong Kong, it is shown that forecasting the largest change before reversal outperforms the k‐step‐ahead forecast in achieving higher trading profits. Copyright © 2000 John Wiley & Sons, Ltd.     

Application of the linear partial information model to forecasting the Swiss timber market

Most often, statistical analyses only provide partial information about the appropriateness of different models, structures and parameters which may underlie the dynamic process that has generated a time series. Linear partial information (LPI), in particular, consists of linear restrictions such as LPI: p_a> p_b, p_a> p_c where p_a denotes the probability that structure a holds. Fuzzy information of this type can be put to use for decision-making by LPI analysis. In this paper, LPI analysis is applied to answer the question of whether subsidizing price, given an abnormal disturbance on the timber market, would contribute to continuous forest management, a stated goal of Swiss environmental policy.     

Estimating and forecasting the long‐memory parameter in the presence of periodicity

We consider one parametric and five semiparametric approaches to estimate D in SARFIMA (0, D, 0)_s processes, that is, when the process is a fractionally integrated ARMA model with seasonality s. We also consider h‐step‐ahead forecasting for these processes. We present the proof of some features of this model and also a study based on a Monte Carlo simulation for different sample sizes and different seasonal periods. We compare the different estimation procedures analyzing the bias, the mean squared error values, and the confidence intervals for the estimators. We also consider three different methods to choose the total number of regressors in the regression analysis for the semiparametric class of estimation procedures. We apply the methodology to the Nile River flow monthly data, and also to a simulated seasonal fractionally integrated time series. Copyright © 2007 John Wiley & Sons, Ltd.     

Master Georg Dörffel and the rise of cometary astronomy

This paper examines the purport of epact tables encountered on scientific instruments, and explains their use. The epact is a valuable chronological aid for calculating the age of the moon. In handbooks of chronology, usually two types of epacts are distinguished: the epact used in medieval times, and the so-called Lilian epact used after 1582 in the Gregorian perpetual calendar. By examining the rules for calculating the age of the moon, it turns out that the Julian and Gregorian epacts encountered on instruments must be distinguished from the medieval and Lilian epacts. It is shown that the Julian epact was already in use in 1478, and that, by adjusting for the shift of ten days in the date of the vernal equinox, the Gregorian epact was derived from it in 1582. The common association of the latter with the Lilian epact employed in the Gregorian perpetual calendar is incorrect. It is further shown that in contrast to the medieval and Lilian epacts, which served purely ecclesiastical purposes, the Julian and Gregorian epacts were mainly used to calculate the true age and zodiacal position of the moon. This knowledge was applied to secular interests such as ‘lunar astrology’, tidal computations, and the conversion of lunar into solar time.     

Intertidal habitat: does the shore level affect the nutritional condition of the shanny (Lipophrys pholis,Teleostei, Blenniidae)?

The nutritional condition of the shanny (Lipophrys pholis, Teleostei, Blenniidae), an intertidal fish, is affected by the shore level on whihc it dwells. Depending on the altitude within the intertidal, zone access to food is restricted for a certain time. A progressive decrease in the feeding time for an individual remaining on an increasingly higher shore level leads to a poorer nutritional condition compared to an individual staying at a lower shore level. Trade-off mechanisms between the feeding time and competition for space and/or predation pressure seem to be responsible for the still high abundance ofL. pholis on the upper shore. Possible consequences for growth and reproduction as well as distribution patterns are discussed.     

Interaction ofRhizobium loti strain and host on the biosynthesis of unusual amino acids in leguminous plants

Summary The effect of differentRhizobium loti strains on the biosynthesis of 2,3-diamino-butanoic acid and 2,4-diamino-3-methyl-butanoic acid in root nodules ofLotus tenuis, Anthyllis vulneraria andLupinus densiflorus has been investigated. Results suggest that biosynthesis isRhizobium strain dependent, that the bacteroid is the site of synthesis of the compounds and that their biosynthesis is confined to the symbiosis.     

Pathogenesis of Plasmodium falciparum malaria: the roles of parasite adhesion and antigenic variation

Malaria results in up to 2.5 million deaths annually, with young children and pregnant women at greatest risk. The great majority of severe disease is caused by Plasmodium falciparum. A characteristic feature of infection with P. falciparum is the accumulation or sequestration of parasite-infected red blood cells (RBCs) in various organs, such as the brain, lung and placenta, and together with other factors is important in the pathogenesis of severe forms of malaria. Sequestration results from adhesive interactions between parasite-derived proteins expressed on the surface of infected RBCs and a number of host molecules on the surface of endothelial cells, placental cells and uninfected RBCs. Some receptors for parasite adhesion have been implicated in particular malaria syndromes, such as intercellular adhesion molecule 1 in cerebral malaria and chondroitin sulfate A and hyaluronic acid in placental infection. The principal parasite ligand and antigen on the RBC surface, P. falciparum erythrocyte membrane protein 1 encoded by a multigene family termed var, is clonally variant, enabling evasion of specific immune responses. An understanding of these host-parasite interactions in the context of clinical disease and immunity may reveal potential targets to prevent or treat severe forms of malaria. Received 25 June 2001; received after revision 22 August 2001; accepted 24 August 2001     

Exponential smoothing: Behavior of the ex-post sum of squares near 0 and 1

When using simple exponential smoothing on a given time series the nature of the relationship between the optimal smoothing constant and the autocorrelation structure of the series remains an unresolved question. Although numerical search routines can easily be used to find optimal values of the smoothing constant, they offer little insight into the nature of the relationship between the estimated smoothing constant and the structure of the underlying time series. We suggest that renewed investigations of the ex-post sum of squares function may prove helpful in this pursuit. Results are presented that illustrate how the optimal smoothing constant depends upon the value used to initialize the smoothing and upon the sample autocorrelation coefficients of the observed series. These results are based on a new formula for the derivative of the ex-post sum of squares function. In particular, the derivative is examined near 0 and 1, where great simplifications occur in its form, thereby facilitating investigations near these points. A necessary and sufficient condition is stated for when the ex-post sum of squares must have a positive derivative at 0 and the autocorrelation coefficients of the differenced series are shown to affect the sign of the derivative near 1. Based on these results, a general algorithm is presented as an alternative to grid search routines for minimizing the ex-post sum of squares.     

Genetic analysis of the kinome and phosphatome in cancer

Protein phosphorylation is a well-characterized biochemical process for reversible regulation of protein activity. Protein kinases and protein phosphatases are the key complementary players in this process, and through their coordinated activity cell homeostasis is tightly controlled. If these enzymes display aberrant activity, cells may undergo unrestrained growth, thus giving rise to complex diseases such as cancer. The technological platform gathered during the Human Genome Project recently allowed the systematic identifi cation of the genetic alterations present in the kinase (the kinome) and the phosphatase (the phosphatome) gene families. These studies suggest that most if not all human tumors carry genetic alterations in at least one phosphatase or kinase gene. Here we integrate the biochemical knowledge on the properties of these molecules with the information collected through their systematic genetic analysis in cancer. We also analyze why the molecular profi ling of the kinome and phosphatome in individual cancers is revolutionizing basic and clinical oncology.Received 13 May 2005; received after revision 30 May 2005; accepted 22 June 2005     

Newton and the classical theory of probability

Summary Probabilistic ideas and methods from Newton's writings are discussed in § 1: Newton's ideas pertaining to the definition of probability, his probabilistic method in chronology, his probabilistic ideas and method in the theory of errors and his probabilistic reasonings on the system of the world. Newton's predecessors and his influence upon subsequent scholars are dealt with in §2: beginning with his predecessors the discussion continues with his contemporaries Arbuthnot and De Moiver, then Bentley. The section ends with Laplace, whose determinism is seen as a development of the Newtonian determinism.An addendum is devoted to Lambert's reasoning on randomness and to the influence of Darwin on statistics. A synopsis is attached at the end of the article.Abbreviations PT abridged Philosophical Transactions of the Royal Society 1665–1800 abridged. London, 1809 - Todhunter I. Todhunter, History of the mathematical theory of probability, Cambridge, 1865 To the memory of my mother, Sophia Sheynin (1900–1970)