Search results for "Oak"
showing 10 items of 181 documents
Adaptive plasticity of blue tits(Parus caeruleus)and great tits(Parus major)breeding in natural and semi‐natural insular habitats
2004
The breeding performance and foraging of blue and great tits, and the abundance of arthropods living on the trees of an oak-wood and of a coniferous reafforestation were studied in Sicily, in order to: 1) compare breeding parameters in natural and semi-natural habitats within the same area; 2) estimate the degree of overlap in peak resource and peak demand of young tits, and the overlap of nestling diet of the two species in the two habitats. Both species had earlier laying dates, laid more eggs and raised more fledglings in the oakwood than in the reafforestation; they achieved the same fledging success within the same habitat type. These differences are probably due to the earlier and hig…
Pozitīvas uzvedības atbalsta stratēģijas 8. klasē
2021
Diplomdarbā autore nodarbojas ar pozitīvas uzvedības stratēģijām, to būtību, pieejām un metodēm. Autore uzskata, ka skolēni var sasniegt labākus rezultātus un uzlabot savu uzvedību, kad skolotāji klasē izmanto pozitīvas uzvedības stratēģijas. Šī pētījuma mērķis ir izpētīt kā pozitīvas uzvedības stratēģijas ietekmē studentu uzvedību un sekmes. Pozitīvā disciplīna ir mācību modelis, kas iesaka izmantot stratēģijas, lai palīdzētu skolotājiem tikt galā ar skolēnu aktivitātēm un attieksmi, kas traucē produktīvam mācību procesam. Autore ir pārliecināta, ka, ieviešot pozitīvas uzvedības stratēģijas, skolotāji spēj izaicinājumus pārvērst par savu stundu iespējām tādā nozīmē, ka klase kļūst par pozi…
Dzīvsudraba akumulācija asara Perca fluviatilis audos Rīgas līča piekrastē
2019
Dzīvsudraba akumulācija asara Perca fluviatilis audos Rīgas līča piekrastē. Darbā tika kvantitatīvi noteikts Hg saturs asara audos noskaidrojot Hg atkarību no asaru izmēra, masas, vecuma un sezonas, kā arī izpētīta barības bāzes ietekme uz Hg saturu asaros. Hg izpēte ir aktuāla, jo ūdens ekosistēmās Hg biomagnificējas augstāko koncentrāciju sasniedzot zivīs, pēc to veselības ir iespējams spriest par ūdens vides ekoloģisko stāvokli. Samazinot Hg slodzes, tā saturs jūras ūdenī ir zems, bieži zem noteikšanas robežas, tomēr atsevišķām zivju sugām novērota augsta Hg bioakumulācija. Eksperimentālajā daļā tika ievākti 642 asari 8-30 cm. Tika konstatēts, ka visi paraugi bija piesārņoti ar Hg diapaz…
Spectral theory of a Neumann-Poincare-type operator and analysis of cloaking due to anomalous localized resonance
2011
The aim of this paper is to give a mathematical justification of cloaking due to anomalous localized resonance (CALR). We consider the dielectric problem with a source term in a structure with a layer of plasmonic material. Using layer potentials and symmetrization techniques, we give a necessary and sufficient condition on the fixed source term for electromagnetic power dissipation to blow up as the loss parameter of the plasmonic material goes to zero. This condition is written in terms of the Newtonian potential of the source term. In the case of concentric disks, we make the condition even more explicit. Using the condition, we are able to show that for any source supported outside a cr…
Crotofolane Diterpenoids and Other Constituents Isolated from Croton kilwae
2023
Six new crotofolane diterpenoids (1-6) and 13 known compounds (7-19) were isolated from the MeOH- CH2Cl2 (1:1, v/v) extracts of the leaves and stem bark of Croton kilwae. The structures of the new compounds were elucidated by extensive analysis of spectroscopic and mass spectrometric data. The structure of crotokilwaepoxide A (1) was confirmed by single -crystal X-ray diffraction, allowing for the determination of its absolute configuration. The crude extracts and the isolated compounds were investigated for antiviral activity against respiratory syncytial virus (RSV) and human rhinovirus type-2 (HRV-2) in HEp-2 and HeLa cells, respectively, for antibacterial activity against the Gram-posit…
Modified ent-Abietane Diterpenoids from the Leaves of Suregada zanzibariensis
2022
The leaf extract of Suregada zanzibariensis gave two new modified ent-abietane diterpenoids, zanzibariolides A (1) and B (2), and two known triterpenoids, simiarenol (3) and β-amyrin (4). The structures of the isolated compounds were elucidated based on NMR and MS data analysis. Single-crystal X-ray diffraction was used to establish the absolute configurations of compounds 1 and 2. The crude leaf extract inhibited the infectivity of herpes simplex virus 2 (HSV-2, IC50 11.5 μg/mL) and showed toxicity on African green monkey kidney (GMK AH1) cells at CC50 52 μg/mL. The isolated compounds 1–3 showed no anti-HSV-2 activity and exhibited insignificant toxicity against GMK AH1 cells at ≥100 μM. p…
High-multiplicity neutron events registered by NEMESIS experiment
2021
Neutron-induced interactions contribute to the signal-mimicking background in deep-underground searches for exotic phenomena such as Dark Matter, neutrino-less double beta decay, proton decay, etc. Apart from radioactive decay, the primary source of neutrons underground are high-energy muons from cosmic showers. While the maximum number of fission neutrons is around six and energies around one MeV, muon-induced interactions may generate hundreds of neutrons, also with high energies. Furthermore, these processes are not yet reproduced in numerical simulations with sufficient reliability. The main goal of the NEMESIS experiment is to improve our knowledge and understanding of cosmic muon-indu…
Tunable scattering cancellation of light using anisotropic cylindrical cavities
2016
Engineered core-shell cylinders are good candidates for applications in invisibility and cloaking.In particular, hyperbolic nanotubes demonstrate tunable ultra-low scattering cross section in the visible spectral range. In this work we investigate the limits of validity of the condition for invisibility, which was shown to rely on reaching an epsilon near zero in one of the components of the effective permittivity tensor of the anisotropic metamaterial cavity. For incident light polarized perpendicularly to the scatterer axis, critical deviations are found in low-birefringent arrangements and also with high-index cores. We demonstrate that the ability of anisotropic metallodielectric nanoca…
Three-dimensional axisymmetric cloak based on the cancellation of acoustic scattering from a sphere.
2013
This Letter presents the design, fabrication, and experimental characterization of a directional threedimensional acoustic cloak for airborne sound. The cloak consists of 60 concentric acoustically rigid tori surrounding the cloaked object, a sphere of radius 4 cm. The major radii and positions of the tori along the symmetry axis are determined using the condition of complete cancellation of the acoustic field scattered from the sphere. They are obtained through an optimization technique that combines genetic algorithm and simulated annealing. The scattering cross section of the sphere with the cloak, which is the magnitude that is minimized, is calculated using the method of fundamental so…
Nuclear Energy Density Optimization: UNEDF2
2014
The parameters of the UNEDF2 nuclear energy density functional (EDF) model were obtained in an optimization to experimental data consisting of nuclear binding energies, proton radii, odd-even mass staggering data, fission-isomer excitation energies, and single particle energies. In addition to parameter optimization, sensitivity analysis was done to obtain parameter uncertainties and correlations. The resulting UNEDF2 is an all-around EDF. However, the sensitivity analysis also demonstrated that the limits of current Skyrme-like EDFs have been reached and that novel approaches are called for.