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1.
Summary 4 of the 5 species ofLimnodynastes of theperoni group show 2n=24. Onlysalmini has 2n=22, thus resembling the species ofPlatyplectron (thedorsalis andornatus complexes) which all show 22 chromosomes. This 2nd group also includes species (ornatus) with very low DNA amounts. From a karyological point of view, the species of thePlatyplectron (plus eventuallysalmini) group appear more differentiated than the species of theperoni group, from which they have probably arisen.Research partly supported by a contribution from C.N.R., Rome.  相似文献   

2.
Summary The chromosomes of three species ofPachybrachis and nine ofCryptocephalus chrysomelids were analyzed. The male meiotic bivalent formula ofP. azureus Suffr.,P. catalonicus Burl. andP. petitpierrei Daccordi is 7II+Xyr.Cryptocephalus sexmaculatus Ol. andC. vittula Suffr. have 13II+Xyp,C. bipunctatus L. 14II+Xyr,C. ochroleucus Steph. andC. ocellatus Drap. 14II+Xyp,C. crassus 01. 15II+Xyr,C. sulphureus 01. 15II+Xyp, the same number as inC. fulvus Goeze with 2n=32 chromosomes, whileC. primarius Har. has 19II+Xyp. The modal chromosome number inCryptocephalus is 2n=30 (about 60% of spp.), and most species are characterized their small chromosomes. The low variation found in the karyotypes of Cryptocephalinae along with their possible interrelationships with allied chrysomelid subfamilies are also discussed.  相似文献   

3.
This paper analyses the revival of Pliny's Naturalis historia within the scientific culture of the late eighteenth and early nineteenth centuries, focusing on a French effort to produce an edition with annotations by scientists and scholars. Between the Renaissance and the early eighteenth century, the Naturalis historia had declined in scientific importance. Increasingly, it was relegated to the humanities, as we demonstrate with a review of editions. For a variety of reasons, however, scientific interest in the Naturalis historia grew in the second half of the eighteenth century. Epitomizing this interest was a plan for a scientifically annotated, Latin-French edition of the Naturalis historia. Initially coordinated by the French governmental minister Malesherbes in the 1750s, the edition was imperfectly realized by Poinsinet a few decades later. It was intended to rival two of the period's other distinguished multi-volume books of knowledge, Diderot and D'Alembert's Encyclopédie and Buffon's Histoire naturelle, to which we compare it. Besides narrating the scientific revival of the Historia naturalis during this period, we examine its causes and the factors contributing to its end in the first half of the nineteenth century.  相似文献   

4.
Alexis Fontaine des Bertins (1704–1771) was the first French mathematician to introduce what we would now regard as results in the calculus of several variables. One example is Fontaine's theorem nF = (?F/?x)x + (?F/?y)y of 1737 for homogeneous expressions F of degree n in x and y. Many years later Fontaine indicated this particular result to have been ‘a continuation of the method of solution’ introduced by him in 1734 to solve the problem of the tautochrones. It is tempting to disregard this announcement, since the method applied to the tautochrones was a method of variations and not manifestly an exercise in the calculus of several variables. Do we have just another case of a mathematician's confusion about the origins of his earlier work? In this paper I describe Fontaine's possible intentions in his remarks.  相似文献   

5.
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 ri (over time i=1, 2, ..., n) for the ith day be given and the investor has to make investment decision di on the ith day with di=1 representing a ‘long' position and di=0 a ‘neutral' position. The investment return is given by rni=1ridicΣn+1i=1didi−1∣, where c is the transaction cost. The mathematical programming problem of choosing d1, ..., dn 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.  相似文献   

6.
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: pa> pb, pa> pc where pa 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.  相似文献   

7.
Summary The thyroid glands of transgenic mice (TM) expressing the genes for human (h) and bovine (b) growth hormone (GH) were studied. The percentages of larger follicles inhGH TM of either sex were significantly greater than in the corresponding normal littermates, and follicles ranging up to 350 m in diameter were present in malehGH TM. In contrast, thyroid follicles were only slightly enlarged in malebGH TM, and were unchanged in femalebGH TM. The serum concentrations of T4 were significantly decreased in malebGH TM and not altered in the other groups. Serum concentrations of T3 were slightly, but significantly increased in femalehGH TM and femalebGH TM, but were unaffected in male TM of either type. Since the principal difference between these foreign GHs in rodents is the additional lactogenic activity of human GH, these results may indicate that the effects of prolactin can influence the development of the thyroid.  相似文献   

8.
Summary Traps containing a mixture of attractants forIps typographus also caught other species of bark beetles. The numbers ofPityogenes chalcographus, Pityogenes conjunctus, andTrypodendron lineatum were too high to be interpreted as accidental captures. The males of the polygamousP. chalcographus were specifically attracted, indicating that theI. typographus pheromone or one of its components acts as a kairomone and primary attractant for the pioneering males ofP. chalcographus.  相似文献   

9.
Zusammenfassung Es wurde die Überspannung vonWasserstoff anEisen in Gegenwart verschiedenerKorrosionsinhibitoren gemessen. Es zeigt sich, daß dieÜberspannung bei der Gegenwart derInhibitoren vergrößert ist. Hieraus wird Folgendes geschlossen: Die Erschwerung der Korrosion durch den Inhibitor ist auf Erhöhung der Überspannung zurückzuführen. Sie beruht nicht auf der Bildung einer schützenden Schicht von adsorbierter Inhibitorsubstanz auf der Eisenprobe.  相似文献   

10.
Summary Estrogen receptors are found in the rat uterine and in the eosinophil-rich human blood leukocyte 24,000g fractions, but not in the low-eosinophil count human blood leukocyte 24,000g fraction. The total number of binding sites per blood eosinophil leukocyte is 7,400 sites per cell, and theK d =5.6×10–10 M.Acknowledgments. This work was supported in part by funds from the Unité de Recherches sur le Métabolisme Moléculaire et la Physio-Pathologie des Stéroïdes de l'INSERM, Hôpital de Bicetre, France, and by grant No. 2015 from the Oficina Técnica de Desarrollo Científico y Creación Artística of the University of Chile.  相似文献   

11.
Summary Allozyme electrophoresis was used to determine the hybrid parentage of the triploid parthenogenetic speciesCnemidophorus exsanguis. 19 of 33 loci were polymorphic inC. exsanguis and/or the 7 potential bisexual progenitors. It was determined from allele distributions thatC. exsanguis containes genomes form 3 different species, probablyC. costatus, C. inornatus andC. septemvittatus.Acknowledgments. We thank R.L. Bezy, W.M. Brown, A.E. Greer, C.S. Lieb, J.L. Patton and K.L. Wright for assistance in the field; the Departments of Game and Fish of Arizona and New Mexico and the Direccion General de la Fauna Silvestre, Mexico for providing collecting permits; and R.L. Bezy, H.W. Greene and D.B. Wake for discussions and criticisms. This research was supported in part by NSF Grants DEB 76-20599 and DEB 81-05615 and by a Research Fellowship in Herpetology from the Natural History Museum of Los Angeles County to DAG.  相似文献   

12.
A 430-bp cDNA encoding the insect antimicrobial peptide defensin was cloned from the housefly, and designated Musca domestica defensin (Mdde). The open reading frame of the cDNA encoded a 92-amino acid peptide with an N-terminal signal sequence followed by a propeptide that is processed by cleavage to a 40-amino acid mature peptide. Northern analysis and in situ hybridization identified the corresponding mRNA in the fat body of bacterially challenged houseflies and in the epidermis of the body wall of naive and challenged houseflies. The Gram-negative bacterium (Escherichia coli) is a strong inducer of the gene. By RT-PCR, Mdde mRNA was also detected in naive and challenged insects. These findings suggest that the defensin gene is constitutively expressed in the epidermis of the housefly body wall. The predicted mature form of Mdde was expressed as a recombinant peptide in E. coli and Pichia pastoris. The recombinant Mdde expressed in Pichia was active against Gram-positive and some Gram-negative bacteria. Received 20 June 2006; received after revision 3 October 2006; accepted 30 October 2006  相似文献   

13.
Zusammenfassung Eine neue Methode der Extrahierung von «Antifertilizin» aus den Samenzellen von Seeigeln,Paracentrotus lividus undArbacia lixula, wurde beschrieben. Der Extrakt zeigte folgende Wirkungen: Neutralisierung des Fertilizins, nicht umkehrbare Agglutinierung der Samenfäden und der Eier bei beiden Seeigelarten.  相似文献   

14.
Zusammenfassung Es wird der Beweis erbracht, dass photoreaktivierungsfähige Sektoren von Zellen einen zusätzlichen Affinitätsparameter zwischer Hefen der GattungenHansenula undPichia bilden und vielleicht wertvolle Daten für die endgültige Erschliessung der intragenerischen Phylogenie derPichia liefern.

These studies were aided in part by a contract No. AT (11-1)-1772 with the U.S. Atomic Energy Commission.  相似文献   

15.
Summary Comparison of the contents of the postpharyngeal gland and cuticular hydrocarbons of five species of ant have shown them to contain the same compounds and to be characteristic of the species. For four species (Formica selysi, Camponotus lateralis, Camponotus vagus andManica rubida), quantitative similarity was very close, but more divergent in the fifth (Myrmica rubra). Glands and cuticle ofM. rubra queens were shown to be closely similar to those of workers, except the glands of queens are larger, but the cuticle of larvae was different from that of adult cuticle and postpharyngeal glands.  相似文献   

16.
Zusammenfassung Der Autor hat bereits früher über den teratogenen Effekt von Thymidin beiD. melanogaster berichtet. Die vorliegende Arbeit befasst sich mit demselben Phänomen bei anderenDrosophila-Arten undMegaselia scalaris (Phoridae). Während der teratogene Effekt beiD. simulans, D. mercatorum undD. funebris der gleiche wie beiD. melanogaster ist, tritt beiD. subobscura andMegaselia scalaris keine teratogene Wirkung auf. Die für die genannten Arten verwendete Thymidinkonzentration erweist sich fürD. hydei als stark toxisch und verhindert die Verpuppung vollkommen. Das Ergebnis zeigt, dass verschiedene genetische Systeme sehr unterschiedlich auf ein und dieselbe chemische Substanz reagieren können.

This work was done in the Institute of Biology of the University of Vienna (Head: Prof. Dr. F.Mainx) and the author is thankful for guidance and laboratory facilities.  相似文献   

17.
Résumé La composition de l'amine acide libre dans les deux espèces deTubularia a été examinée au moyen de la chromatographie. Les tissus d'hydranthe deT. crocea avaient 21 amines acides libres dont 18 ont été identifiées dans les hydrocauli et dans les hydranthes régénérés deT. crocea, 19 dans les hydranthes deT. spectabilis et 14 dans les hydrocauli deT. spectabilis. La différence principale entre les hydranthes et les hydrocauli réside dans la distribution de certaines taches non-identifiées qui apparurent dans les chromatogrammes developpés avec la ninhydrine et les réactifs pour les groupes des imidazoles, guanidines, ou sulfhydriles.

Part of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Florida State University. Aided by a National Science Foundation Predoctoral Fellowship and a National Science Foundation Grant to Dr. C. B.Metz, Contribution number 122 from the Oceanographic Institute, Florida State University.  相似文献   

18.
This paper extends the ‘remarkable property’ of Breusch (Journal of Econometrics 1987; 36 : 383–389) and Baltagi and Li (Journal of Econometrics 1992; 53 : 45–51) to the three‐way random components framework. Indeed, like its one‐way and two‐way counterparts, the three‐way random effects model maximum likelihood estimation can be obtained as an iterated generalized least squares procedure through an appropriate algorithm of monotonic sequences of some variance components ratios, θi (i = 2, 3, 4). More specifically, a search over θiwhile iterating on the regression coefficients estimates β and the other θjwill guard against the possibility of multiple local maxima of the likelihood function. In addition, the derivations of related prediction functions are obtained based on complete as well as incomplete panels. Finally, an application to international trade issues modeling is presented. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

19.
20.
Summary Sticky traps containing (+)-lineatin, the pheromone of the ambrosia beetle,Trypodendron lineatum, attracted the predatorThanasimus formicarius to about the same extent as traps baited with ipslure, the pheromone blend used for mass-trappingIps typographus. The results indicate thatT. lineatum is an important prey forT. formicarius early in the season before the main prey becomes active. Addition ofexo-brevicomin to ipslure and ethanol and/or -pinene to (+)-lineatin did not significantly influence the catches of the predator.  相似文献   

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