42 research outputs found
Intrinsic Regular Surfaces of low codimension in Heisenberg groups
No full textIn this paper we study intrinsic regular submanifolds of , of low co-dimension in relation with the regularity of their intrinsic parametrization. We extend some results proved for one co-dimensional -regular surfaces, characterizing uniformly intrinsic differentiable functions acting between two complementary subgroups of the Heisenberg group , with target space horizontal of dimension , with , in terms of the Euclidean regularity of its components with respect to a family of non linear vector fields . Moreover, we show how the area of the intrinsic graph of can be computed through the component of the matrix identifying the intrinsic differential of
A reverse coarea-type inequality in Carnot groups
No full textWe prove a coarea-type inequality for a continuously Pansu differentiable
function acting between two Carnot groups endowed with homogeneous distances.
We assume that the level sets of the function are uniformly lower Ahlfors
regular and that the Pansu differential is everywhere surjective
The Fractional Powers of the Sub-Laplacian in Carnot Groups Through an Analytic Continuation
No full textIn this paper we construct the fractional powers of the sub-Laplacian in Carnot groups through an analytic continuation approach. In addition, we characterize the powers of the fractional sub-Laplacian in the Heisenberg group, and as a byproduct we compute the k-th order momenta with respect to the heat kernel
Area formula for regular submanifolds of low codimension in Heisenberg groups
No full textWe establish an area formula for the spherical measure of intrinsically regular submanifolds of low codimension in Heisenberg groups. The spherical measure is constructed by an arbitrary homogeneous distance. Among the arguments of the proof, we point out the differentiability properties of intrinsic graphs and a chain rule for intrinsically differentiable functions
Role of the electronic properties of azurin active site in the electron-transfer process
No full textElectron transfer proteins, such as azurin (a blue copper protein), are promising candidates for the implementation of biomolecular nanoelectronic devices. To understand the details of electron transfer in redox active azurin molecules, we performed plane-wave pseudo-potential density functional theory (DFT) calculations of the protein active site in the two possible oxidation states Cu(I) and Cu(II). The ab initio results are used to discuss how the electronic spectrum and wavefunctions may mediate the shuttling of electrons through the copper ion. We find that the Cu-ligand hybridization is very similar in the two charge states of the metal center, but the energy spectrum changes substantially. This result might indicate important effects of electronic correlations in the redox activity and consequent electron transfer through the Cu site
Large angle convergent beam electron diffraction strain measurements in high dose helium implanted silicon
No full textLarge angle convergent beam electron diffraction (LACBED) technique has been applied to TEM cross section of silicon samples implanted with 2x1016 cm-2 He ions at an energy of 20 KeV in order to evaluate the stress/strain field in the implanted layer. The stress/strain field depends on the mismatch between the lattice of the silicon substrate and the one of the defective layer which contains clusters of point defects and small He bubbles. Lattice mismatch causes changes in the spacing and inclination of diffraction planes producing a shift and a rotation of diffraction intensity lines (Bragg contours (BC)) visible in LACBED patterns. In particular, when the electron beam is parallel to the rotation axis, the BC simply rotate. This is the case of mismatches observed with (333) BC when the electron beam is incident on the sample along a direction close to zone axis. Measurements show a peak of the stress/strain field (intensity 1.5 GPa) at a depth close to the helium projected range, where small bubbles occasionally form aggregate oriented along direction
NOTA MORFO-BIOLOGICA SULL' EULECANIUM CORNI (BOUCHÈ) SSP. APULIAE NOV.
No full textL'Autore studia la morfologia dei vari stadi di sviluppo dell'E. corni e, nella forma vivente sul susino e sulla vite in Puglia, trova delle differenze tra gli individui da lui esaminati e quelli descritti dagli altri Autori (SILVESTRI, CUSCIANNA, MARCHAL, ecc.): sia la neanide della II età, sia la femmina adulta presentano un numero differente di sbocchi delle glandole dorsali submarginali a doppio cerchio; per questo motivo si è ritenuto di distinguere questa popolazione costituendo la nuova sottospecie « apuliae ». La biologia di questa cocciniglia sulla varietà di vite Ohannez differisce anche dalla biologia studiata su altre piante in altre zone d'Italia. Sverna la neanide della IIetà tra le screpolature dei tralci vecchi e, negli stessi ricoveri invernali, questa diviene adulta e compie una generazione primaverile che si conclude entro maggio. Le neanidi in giugno si diffondono sulle foglie e sulle parti verdi della pianta dove, durante l'estate, diventano adulte e ovodepongono. Questa generazione estiva si compie entro agosto-settembre; vi possono essere femmine in ovodeposizione anche in ottobre ed eccezionalmente in novembre. Le neanidi nate dall'agosto fino all'autunno più o meno inoltrato si nutrono sulle foglie sino all'approssimarsi della loro caduta, quindi si ritirano sui tralci per trascorrere l'inverno. In Puglia il Lecanino è presente un po' ovunque, ma solo in qualche zona produce danni economici al viticoltore. L'E. corni è combattuto dalla Scutellista cyanea Mots. e dal Coccophagus lycimnia Walk. (Imenotteri Calcididi), che rivestono una certa importanza solo nella generazione estiva in quanto mai sono stati osservati in primavera. Viene studiato l'effetto del Parathion sia sul fitofago che sulla Scutellista. La lotta artificiale può essere attuata sia con trattamenti invernali con olii minerali, sia con esteri fosforici, nel mese di giugno. The author refers on morphology and bionomics of Eulecanium corni (Bouché) apuliae ssp. n. (Homoptera, Coccoidea, Lecaniidae). Larvae and adults characters of taxonomic value have been examined. The 2nd instar larva dorsally shows (in the sub-margina area) l0-13 glandular openings, which have a double ridge and an internai tube: 67% of the specimens examined have 12 glandular openings. These are very important characters for distinguish the Eulecanium species. The observations here reported differ from those of other precedent authors (CUSCIANNA, LEONARDI, MARCHAL, SILVESTRI, etc.) for E. corni collected in other european countries. Bionomics of E. corni has been studied on vines (Ohannez cultivar) near Stornara (Foggia, Apulia). 2nd instar larva hibernante on the vinestocks, and here they do last moult in springtime. Adult femal layis eggs, from the end of Aprii up to May. The new hatched larvae scatter on the leaves and green parts of the plants, where they develop and moult twice. Here they also settle definitively and in August-September (become adults) thety lay eggs once again. Larvae hatched in this period stay on the leaves until these are near to fall down; the larvae once moult on leaves and then they retire on vine-branches, where they hibernate in the cracks. Sex ration is 10 in springtime generation; no one male has been observed in summer generation. E. corni apuliae injuried plants with direct and indirect damages (by feeding and with its sugary escrements on with develop parasitic fungy). Natural enemis of E. corni apuliae are in Apulia two Hymenoptera: Scutellista cyanea Mots. and Coccophagus lycimnia (Walk.). A Parathion application on leaves for controlling E. corni apuliae larvae in August-Settember causes death of many adults of Scutellista cyanea under the body of the host females. 2nd instar larvae may be controlled in June on the laves by organophosphoric compounds treatments
Within-plant distribution of Parthenolecanium corni (Bouché) (Hemiptera: Coccidae) on grapevine
No full textThe European fruit lecanium, Parthenolecanium corni (Bouché) (Hemiptera: Coccomorpha: Coccidae), is an important grapevine pest in all grape production regions. Due to its hidden way of life, knowing which vine parts to sample when monitoring is important for early infestation detection. Within-plant distribution of this pest was studied throughout the whole vegetative season, in a three-year field trial carried out in Neštin, Serbia. Grapevine trunk and cane were each divided in three equal sections. Reference point was the merging spot of trunk and cane. Canopy was divided in nine equal quadrants. The number of P. corni individuals in each part was estimated. It was recorded that P. corni adult females and nymphs prefer certain grapevine parts for their settlement. A significant difference between the number of adult females recorded on different grapevine woody parts was observed, with the highest number recorded on the first third of cane. The nymphs, which infest canopy, were unevenly distributed. Their number was highest on the leaves nearby preferred adult female settlement spots (first third of cane) throughout the whole season. The number of adult females and nymphs showed a decreasing trend with the increase of distance from the reference point. The information gathered during this research can be useful for early detection and monitoring of P. corni infestations in the vineyards. © 2023, The Author(s), under exclusive licence to Springer Nature B.V
Evolution of vacancy-like defects in He-implanted (100) Si studied by thermal desorption spectrometry
No full texthermal desorption spectrometry (TDS) has been applied to investigate the thermal evolution of vacancy-like defects in helium-implanted (100) silicon samples with a dose of 2x1016 cm-2 at 20 keV. The measured spectra present features which can be interpreted as fingerprints of the modifications occurring in the sample. The defects that are recognized which affect the desorption are: thermally unstable helium-vacancy complexes, pressurized gas bubbles organized in planar structures (cracks) and thermally stable cavities. The attribution is supported by the results obtained by complementary techniques, such elastic recoil detection, channeling Rutherford backscattering spectrometry, cross sectional transmission electron microscopy and positron annihilation spectroscopy which have been employed on isothermally pre-annealed samples in the range 100-800o
