7,934 research outputs found
Undulation textures at the phase transitions of some alkyloxybenzoic acids
We observed undulated smectic textures for some compounds of the
4,n-alkyloxybenzoic (nOBAC) acid series, at transitions between the smectic and
the isotropic phase and between the smectic and nematic phase. Studied
compounds were 12OBAC, 16OBAC and a binary mixture of 12- and 16OBAC. The
undulations are dressing a usual Schlieren texture. In the case of the binary
mixture, an interesting fingerprint pattern is observed too
Do interactions between plant roots and the rhizosphere affect parasitoid behaviour?
Multitrophic interactions are powerful forces shaping the structure of living communities. Plants encounter a great diversity of organisms in their environment: some of these interactions are beneficial (e.g. symbiotic fungi and insect pollinators) while some are detrimental (e.g. herbivorous insects and pathogenic micro-organisms). Multitrophic interactions between below-ground and above-ground organisms are receiving increasing attention because they may influence plant defences against biotic and abiotic stresses. In this study we show that an arbuscular mycorrhizal symbiosis makes tomato plants significantly more resistant towards aphids, by enhancing both direct defences, both attractivity towards aphid parasitoids
Quantum mechanics with time-dependent parameters
Smooth composite bundles provide the adequate geometric description of
classical mechanics with time-dependent parameters. We show that the Berry's
phase phenomenon is described in terms of connections on composite Hilbert
space bundles.Comment: 7 pages, LaTe
Tettigoniidae (Orthoptera) ovipositing in old galls of Dryocosmus kuriphilus (Hymenoptera: Cynipidae)
Authors report some biological notes on two species of Orthoptera Tettigoniidae emerged from old spongy-woody galls of Dryocosmus kuriphilus Yasumatsu, 1951 collected in April 2015 from some areas of Sicily (Italy): Leptophyes sicula Kleukers, Od\ue9 et Fontana, 2010 (Phaneropterinae) and Cyrtaspis scutata (Charpentier, 1825) (Meconematinae). Between the end of April and the first days of May 30 neanids emerged from the galls, were reared and their cycle followed. While L. sicula laid eggs in groups, C. scutata laid single eggs inside the galls; both species have shown that in a few years they adapted in exploiting this new shelter for egg laying. No interaction with the gall inducing insect was noted
First GPS-tracking of Cory’s shearwater in the Mediterranean Sea.
The behaviour and the ecology of seabirds such as albatrosses, petrels and shearwaters have been subject of numerous studies, often employing the most recent technologies to track birds during their foraging trips. Until now, however, big oceanic species have been preferred for these studies because of the dimensions and weight of the devices. New light GPS loggers (<9g) were used to track foraging trips of a medium-sized species, the Cory’s shearwater, for the first time in the Mediterranean Sea. The tracks obtained in our study showed that Mediterranean Cory’s shearwaters alternatively used one of two different fishing areas. Various explanations could account for this difference; one of these could be that the two directions have a different relevance for the birds being for chick- and self-provisioning. This study provides new hypotheses concerning the behaviour of Cory’s shearwaters in the Mediterranean Sea, which is a different environment respect to previously studied oceans
Cepheid Masses: FUSE Observations of S Mus
S Mus is the Cepheid with the hottest known companion. The large ultraviolet
flux means that it is the only Cepheid companion for which the velocity
amplitude could be measured with the echelle mode of the HST GHRS.
Unfortunately, the high temperature is difficult to constrain at wavelengths
longer than 1200 \AA because of the degeneracy between temperature and
reddening. We have obtained a FUSE spectrum in order to improve the
determination of the temperature of the companion. Two regions which are
temperature sensitive near 16,000 K but relatively unaffected by H
absorption (940 \AA, and the Ly wings) have been identified. By
comparing FUSE spectra of S Mus B with spectra of standard stars, we have
determined a temperature of 17,000 500 K. The resultant Cepheid mass is
6.0 0.4 M. This mass is consistent with main sequence
evolutionary tracks with a moderate amount of convective overshoot.Comment: accepted to Ap
Andricus cydoniae Giraud, 1859 Junior Synonym of Cynips coni-fica Hartig, 1843, as Experimentally Demonstrated (Hymenoptera: Cynipidae: Cynipini)
We demonstrated the life cycle closure of Cynips conifica Hartig, 1843 (presently Andricus conifi-cus), previously supposed on the basis of molecular data, and the identity of the sexual genera-tion, through laboratory experiments. As a consequence, Andricus cydoniae Giraud, 1859 became a junior synonym of A. conificus (Hartig, 1843). We provide illustrations and a diagnosis for adults and galls, observations on biology, and information on distribution. Moreover, as sexual galls of A. conificus cannot be distinguished from those of Andricus multiplicatus, a detailed com-parison between sexual galls and adults of these two species is reported
Crystal bending in triple-Laue X-ray interferometry. Part II. Phase-contrast topography
In a previous paper [Sasso et al. (2023). J. Appl. Cryst. 56, 707-715], the operation of a triple-Laue X-ray interferometer having the splitting or recombining crystal cylindrically bent was studied. It was predicted that the phase-contrast topography of the interferometer detects the displacement field of the inner crystal surfaces. Therefore, opposite bendings result in the observation of opposite (compressive or tensile) strains. This paper reports on the experimental confirmation of this prediction, where opposite bendings were obtained by copper deposition on one or the other of the crystal sides
Crystal bending in triple-Laue X-ray interferometry. Part I. Theory
The measured value of the (220) lattice-plane spacing of silicon 28 using scanning X-ray interferometry is essential to realize the kilogram by counting Si-28 atoms. An assumption made is that the measured lattice spacing is the bulk value of an unstrained crystal forming the analyser of the interferometer. However, analytical and numerical studies of the X-ray propagation in bent crystals suggest that the measured lattice spacing might refer to the analyser surface. To confirm the result of these studies and to support experimental investigations of the matter by phase-contrast topography, a comprehensive analytical model is given of the operation of a triple-Laue interferometer having the splitting or recombining crystal bent
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