La formule chromosomique chez cinq espèces de Chiroptères

Summary Five species ofChiroptera were studied and the following numbers were found:Rhinolophus hipposideros Bechst.N=27;Barbastella barbastellus Schr.N=16;Plecotus auritus L.N=16;Myotis myotis Bork.N=21;Miniopterus schreibersii Kuhl,N=23. Centric fusions occur in the chromosomal evolution ofChiroptera. Sex-chromosomes ofX-Y type.     

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.     

Synthesis of eledoisin

Résumé LeL-pyroglutamyl-L-prolyl-L-séryl--N-carbotert.-butoxy-L-lysyl azide et leL-aspartyl-L-alanyl-L-phénylalanyl-L-isoleucyl-glycyl-L-leucyl-L-méthioninamide ont été synthétisés, puis condensés enL-pyroglutamyl-L-prolyl-L-séryl--N-carbo-tert. butoxy-L-lysyl-L-aspartyl-L-alanyl-L-phénylalanyl-L-isoleucyl-glycyl-L-leucyl-L-méthioninamide. Après traitement par l'acide trifluoroacétique, ce dernier a donné l'endécapeptide,L-pyroglutamyl-L-prolyl-L-séryl-L-lysyl-L-aspartyl-L-analyl-L-phénylalanyl-L-isoleucyl-glycyl-L-leucyl-L-méthioninamide, qui s'est montré doué des mêmes propriétés chimiques, physiques et biologiques que l'élédoisine naturelle.     

Simple integrated rate equations for reversible bimolecular reactions

Summary If the complete rate equations for reversible, one-step, bimolecular reactions are written withP _e–P as the concentration variable (whereP _e is the equilibrium, andP is the instantaneous, product concentration), the 3 possible stoichiometries can be reduced to a single straightforward differential equation. This can be solved very economically. For each stoichiometry, weret is time,k ₁ is the forward rate constant,K _e is the equilibrium constant, and P isP–P _o. The termsP _c–P _o andD+P _c–P _o are the physically possible and physically impossible roots of the quadratic equation forP _e–P _o in terms of the initial concentrations andK _c.D is the discriminant in this equation. All 3 quantities can be calculated if the equilibrium constant is known. A plot oft against ln{[1–P/(D+P _c–P _o)]/[1–P/(P _c–P _o)]} should be a straight line for any second order reaction. For each stoichiometry,P _c–P _o approachesA _o, the initial concentration of the first reactant, as the equilibrium constant increases. When a second reactant is present,D+P _e–P _o approachesB _o. The limiting equation is then that of an irreversible bimolecular reaction. For AP+Q,D approaches –K _e as the equilibrium constant becomes large, and the value of the second logarithmic term in the integrated equation approaches zero. The limiting equation is that of an irreversible, unimolecular reaction.Acknowledgments. I thank Dr. Athel Cornish-Bowden for many helpful discussions. This work was partially supported by a grant from Utah State University.     

Differenzierendes Kaulquappen-Fressen durch Molche

Summary Differential predation on tadpoles by newts (Triturus). 4 EuropeanTriturus species (T. alpestris, T. cristatus, T. helveticus, T. vulgaris) feed upon the tadpoles of the following Anura species which occur in sympatry with the newts:Rana esculenta, R. temporaria andBombina variegata. OnlyTriturus cristatus prey also upon the tadpoles ofBufo bufo andB. calamita. Triturus alpestris, T. helveticus andT. vulgaris do not eat anyBufo tadpoles. Even larvae ofTriturus alpestris prey upon tadpoles ofRana esculenta, R. ridibunda andBombina variegata but avoid tadpoles ofBufo calamita.

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Mit Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung.     

Chromosome numbers in five species of pentatomidae reut (Hemiptera - Heteroptera)

Zusammenfassung Die 5 SchildwanzenartenCoptosoma scutellatum Geoffr.,Elasmucha grisea L.,Legnotus picipes Fall.,Phimodera lapponica Zett. undEurygaster testudinaria Geoffr. wurden während der Spermatogenese karyologisch geprüft. Mit Ausnahme vonLegnotus picipes Fall. wurde die diploide Chromosomenzahl mit 2M+8A+X+Y bestimmt.     

Parallel evolution of multiple sex-chromosome systems in the phyllostomatid bats,Carollia andChoeroniscus

Resumen Se describen los cariotipos deCarollia perspicillata, C. brevicauda, yC. castanea de Costa Rica y del Perú, y deChoeroniscus godmani de Costa Rica. La sistema de multiple cromosomas sexuales de machosXY ₁ Y ₂/hembrasXX reportado por investigadores anteriores se encontraba en todos individuos con la excepcion deC. castanea del Perú yChoeroniscus godmani de Costa Rica. Estas poblaciones se consideran de haberse mantenido la sistema primitiva de cromosomas sexualesXX/XY.     

Sopra un caso particolare della superficie F 4 (3) di M. Noether

Summary The Noetherian surfaceF ₄ ⁽³⁾ , which is represented on a plane by a linear ³ system ofC ₉(A ₁ ³ A ₂ ³ A ₃ ³ A ₄ ³ A ₅ ³ A ₆ ³ A ₇ ³ A ₈ ³ A ₉ ² A ₁₀), possesses generally only one linear pencil of elliptic cubics. IfA _i (i=1, 2, , 9) are the basis points of aHalphen pencil ofC ₉,A ₁₀ is infinitely near toA ₉, and in this caseF ₄ ⁽³⁾ is a not trivial example of such a surface with two pencils of elliptic cubics.     

Unstable genetic system inDrosophila melanogaster: I. Instability at theCinnabar locus

Summary A mutant strain containing acinnabar allele (cn ^rbr ,rojo brillante) is reported, that produces wild-type revertants at thecinnabar (cn) locus. Incn ^rbr /cn heterozygotes the rate of mutation is highly increased. The presence of a mutator agent acting premeiotically is indicated.D.L. Lindsley and E.H. Grell, Genetic variations ofDrosophila melanogaster. Carnegie Institution of Washington, Washington, 1968; Publication No. 627.     

Zur Stratigraphie der säugetierführenden Schichten von Java

Summary According to recent geological and paleontological investigations thePithecanthropus-beds of Java are pleistocene in age. The examinations of the fossil mammalian faunæ of the island are of utmost importance for this age-determination and the following faunæ can be recognized:Tji Djolang-fauna: Middle Pliocene.Kali Glagah-fauna: Upper Pliocene.Djetis-fauna withPithecanthropus: Lower Pleistocene.Trinil-fauna withPithecanthropus: Middle Pleistocene.Ngandong-fauna withHomo neanderthalensis soloensis: Upper Pleistocene.Sampoeng-fauna with a primitive type of the Wedda-Dravida-Australoid group: Subrecent. — Micropaleontological examinations of smallerForaminifera from marine equivalents of thePithecanthropus-beds confirm the age-determinations based on mammalia. — Recent field investigations prove that the lower and middle pleistocenePithecanthropus-beds are distinctlyfolded by a post-middle-pleistocene movement; the upper pleistocene Ngandong-terraces are not folded at all.     

Chemical and tactile communication between the root aphid parasitoidParalipsis enervis and trophobiotic ants: consequences for parasitoid survival

Females of the aphid parasitoidParalipsis enervis received liquid food by regurgitation (trophallaxis) from workers of the ant speciesLasius niger, but were not fed by workers ofMyrmica laevinodis andTetramorium caespitum. WhileP. enervis was not treated aggressively by workers of any of these species,Lasius flavus workers killed the parasitoid. This different ant behaviour resulted in a different parasitoid longevity. WhileP. enervis survived for only 10 min in the presence ofL. flavus (due to ant aggression) or for approximately one day in the presence ofT. caespitum andM. laevinodis (due to lack of trophallaxis), survival increased significantly to more than five days in the presence ofL. niger, which provided food regularly to the parasitoids. Our study suggests thatP. enervis mimics behavioural signals ofL. niger, as well as odor cues of its host aphidAnoecia corni, to avoid aggression byL. niger.     

Karyotypic data for five species of anguid lizards

Zusammenfassung Die Chromosomensätze von 5 Eidechsenarten der Familie Aguidae, davon vier vom GenusGerrhonotus und eine vom GenusDiploglossus werden beschrieben.D. costatus ist 2n=36 mit 12 grossen metazentrischen Chromosomen und 24 Mikrochromosomen.G. multicarinatus ist 2n=48,G. paucicarinatus 2n=46 undG. coeruleus 2n=38. Diese 3 Arten haben einen identischen «nombre fondamentale» von 48 und alle haben 26 Mikrochromosomen.G. monticolus besitzt 2n=30. Die Anzahl der Mikrochromosomen ist auf 12 reduziert.     

On the usefulness of macroeconomic forecasts as inputs to forecasting models

A forecasting model for y_t based on its relationship to exogenous variables (e.g. x?_t) must use x?_t, the forecast of x?_t. An example is given where commercially available x?_t's are sufficiently inaccurate that a univariate model for y_t appears preferable. For a variety of types of models inclusion of an exogenous variable x?_t is shown to worsen the y_t forecasts whenever x?_t must itself be forecast by x?_t and MSE (x?_t) > Var (x?_t). Tests with forecasts from a variety of sources indicate that, with a few notable exceptions, MSE (x?_t) > Var (x?_t) is common for macroeconomic forecasts more than a quarter or two ahead. Thus, either:

• (a) available medium range forecasts for many macroeconomic variables (e.g. the GNP growth rate) are not an improvement over the sample mean (so that such variables are not useful explanatory variables in forecasting models), and/or
• (b) the suboptimization involved in directly replacing x?_t by x?_t is a luxury that we cannot afford.

     

Furan fatty acid steryl esters from the marine spongeDictyonella incisa which show inflammatory activity

Summary Three new furan fatty acids, (9Z, 19Z)-3, 6-epoxyhexacosa-3,5,19-tetraenoic acid (1a), (8Z, 11Z, 14Z, 17Z)-3, 6-epoxyeicosa-3,5,8,11,14,17-hexaenoic acid (2a), and (8Z, 11Z, 14Z, 17E)-3, 6-epoxyeicosa-3,5,8,11,14,17-hexaenoic acid (3a), and a new polyunsaturated fatty acid (5Z, 8Z, 11Z, 14Z, 17E)-eicosa-5,8,11,14,17-pentaenoic acid (6a), present in the spongeDictyonella incisa as the respective steryl esters, have been isolated as methyl esters and their structures have been determined by spectral and chemical analysis. The furan fatty acid esters have shown a high inflammatory activity, which suggests their potential role as feeding deterrents.     

The somatic chromosomes of 3 lizard species:Gekko gecko,Iguana iguana,andCrotaphytus collaris

Zusammenfassung Die somatischen Chromosomen der 3 EidechsenartenGekko gecko (2N=38),Iguana iguana (2N=34) undCrotophytus collaris (2N=36), werden dargestellt.G. gecko besitzt metazentrische, subteleozentrische und teleozentrische Elemente, aber keine Mikrochromosomen.I. iguana undC. collaris besitzen Makrochromosomen (6 Paare) und Mikrochromosomen. Bei den ArtenG. gecko undI. iguana waren in keinen von beiden Geschlechtern heteromorphische Chromosomenpaare nach zuweisen.

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Supported by Project No. 417 from the U.S. Children's Bureau and Grant No. 08737 from the National Cancer Institute.     

Communications préliminaires sur les chromosomes des Plécoptères

Summary The chromosomal sets of five species ofPerlodidæ (Plecoptera) are given in the present paper. The sexual chromosomes belong to three distinct types:X-O,X ₁-X ₂,X ₁-X ₂-X ₃. The author shows that these three types are likely derived from the most primitive patternX-Y, by translocation and inversion.     

Vorgänge bei pH-Änderung und bei Belichtung eines Anthocyanidins

Summary The anthocyanidin investigated here exists below pH 4 as a cationAH ₂ ⁺ (wave length of absorption maximum _max=459 mµ), between pH 5 and 7 in the neutral formAH ( _max=492 mµ) and above pH 8 as an anionA ^– ( _max=537 mµ). At pH 5 the freshly dissolved substance is partially converted into a colourless formBH ( _max=372 mµ) and a chemical equilibrium betweenAH andBH is reached within 1 h. A kinetic study of the process of formation ofBH shows that an intermediate productZ is formed. This process can be reversed by light exposure. It can be concluded from a kinetic investigation by using flash light thatBH is transformed by the absorbing light into a new substanceL ( _max 275 mµ and 225 mµ), andL changes partially intoBH, partially intoZ, which itself is transformed partially intoAH ₂ ⁺ ,AH,A ^–, partially intoBH. The reactionZ AH,AH ₂ ⁺ ,A ^– is proportional to the concentration of protons [H ⁺], the reactionZ BH independent of [H ⁺]. Thus a photochemical production ofAH ₂ ⁺ ,AH,A ^– fromBH is readily obtained in the presence ofH ⁺ and not obtained in the absence ofH ⁺.     

Further studies on free amino-acids and peptides in eggs and embryos of different sea-urchin species and hybrids

Zusammenfassung Als Fortsetzung früherer Untersuchungen der freien Aminosäuren und Peptiden in Eiern und Embryonen verschiedener Seeigelarten, wurde das Muster der Ninhydrin-positiven Stoffe vonEchinocardium cordatum, Psammechinus microtuberculatus undGenocidaris maculata papierchromatographisch untersucht. DieEchinocardium-Eier zeichnen sich durch ihre hohe Konzentration an Valin (Fig. 1A, Fleck 16) und Leucin (Fleck 9) aus, welche bei allen übrigen von uns untersuchten Arten nur in sehr geringer Menge auftreten. Ferner sind sie durch das Vorkommen eines spezifischen Stoffes charakterisiert, der nur beiArbacia lixula nachgewiesen wurde (Fleck 17).Psammechinus microtuberculatus undGenocidaris maculata unterscheiden sich in den Peptiden. DiePsammechinus-Eier enthalten einen Stoff, der wahrscheinlich mit dem Tripeptid vonSphaerechinus granularis identisch ist (Fig. 1B, Fleck Nr. 23). InGenocidaris-Eiern wurde ein Peptid registriert, das auch beiParacentrotus lividus vorkommt (Fig. 1C, Fleck Nr. 21).Es wurden ferner Messungen von Eivolumen, Total-stickstoff und Totalmenge der freien Ninhydrin-positiven Substanzen des unbefruchteten Eies durchgeführt. Das Eivolumen und der Gesamtstickstoffgehalt sind beiEchinocardium cordatum am grössten, beiArbacia lixula am geringsten. DieEchinocardium-Eier sind durch ihren hohen Gehalt an freien Aminosäuren gekennzeichnet. Sie enthalten rund 7mal mehr solche Stoffe pro Ei als dieArbacia-Eier; zwischenParacentrotus lividus undSphaerechinus granularis zeigen die Messwerte keinen deutlichen Unterschied.     

Multiple phosphoglucomutase alleles in two species ofMansonia mosquito

Summary Multiple phosphoglucomutase (E.C.2.7.5.1) alleles are found in the mosquitoesMansonia crassipes andM. uniformis. The present study reveals 4Pgm alleles, of whichPgm ^B andPgm ^C are common to both species whilePgm ^A is present only inM. crassipes andPgm ^D only inM. uniformis. The frequencies in both species accord well with Hardy-Weinberg expectations. The most frequent allele is that controlling a phenotype with an intermediate electrophoretic mobility, viz.Pgm ^B inM. crassipes andPgm ^C inM. uniformis.This work is supported in part by a University of Malaya research grant to the senior author.