| 1. |
- Andrijauskas, T., et al.
(författare)
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Thomas-Fermi and Poisson modeling of gate electrostatics in graphene nanoribbon
- 2012
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Ingår i: Lithuanian Journal of Physics. - : Lithuanian Physical Society. - 1648-8504. ; 52:1, s. 63-69
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Tidskriftsartikel (refereegranskat)abstract
- We describe a simple graphene nanoribbon and bottom gate system and present numerical algorithms for solving Poissons and Thomas-Fermi equations for electrons in the graphene nanoribbon. The Poissons equation is solved using finite difference and finite element methods. Using the Poisson and Thomas-Fermi equations we calculate an electrostatic potential and surface electron density in the graphene nanoribbon. Finally, the Poisson-Thomas-Fermi model for the graphene nanoribbon is compared to a tight-binding Hartree model. The results show a good correspondence with the tight-binding model. The developed solver of the Poissons equation can be used in the future calculations of more complex graphene and gate systems.
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| 2. |
- Gegzna, V., et al.
(författare)
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Methods for autofluorescence analysis of uterine cavity washings
- 2015
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Ingår i: Lithuanian Journal of Physics. - : Lithuanian Academy of Sciences. - 1648-8504. ; 55:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- The diagnostics of endometrial pathology can be done by obtaining information at the molecular level, e. g. using the autofluorescence-based technique. Thus, for the first time an experimental study was performed on waste material of uterine cavity washing specimens to evaluate suitability of the technique for diagnostics. The specimens were obtained from 32 patients who had a conventional uterine hydrosonography procedure. A portable Nd:YAG 355 nm microlaser was used to excite autofluorescence at the point of care. Various algorithms of multivariate curve resolution and artificial neural networks were utilized for spectra analysis. The spectra were classified according to histological and ultrasound diagnosis. Receiver operating characteristic (ROC) curve analysis was used to make statistical decisions. The results showed that it was possible to distinguish all compared groups: pathologic vs non-pathologic endometrium (sensitivity 97.3 +/- 5.2%, specificity 91.7 +/- 7%, AUC (area under the ROC curve) 0.96 +/- 0.04), malignant endometrium vs endometrial polyps (sensitivity 100 +/- 0%, specificity 92.0 +/- 10.6%, AUG = 0.98 +/- 0.07), and secretory menstrual cycle phase vs proliferative phase (sensitivity 87.5 +/- 13.2%, specificity 94.4 +/- 7.4%, AUG = 0.88 +/- 0.10). To conclude, uterine cavity washing specimens could be used for endometrial pathology recognition using the autofluorescence-based technique in clinical setting. It will possibly speed up the treatment decision making for endometrial pathology.
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| 3. |
- Marcinkevičius, Saulius, et al.
(författare)
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Multimode scanning near-field photoluminescence spectroscopy and its application for studies of ingan epitaxial layers and quantum wells
- 2018
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Ingår i: Lithuanian Journal of Physics. - : Lithuanian Academy of Sciences. - 1648-8504 .- 2424-3647. ; 58:1, s. 76-89
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Tidskriftsartikel (refereegranskat)abstract
- The paper reviews our recent achievements in developing a multimode scanning near-field optical microscopy (SNOM) technique. The multimode SNOM apparatus allows us to simultaneously measure spatial variations of photoluminescence spectra in the illumination and illumination-collection modes, their transients and sample surface morphology. The potential of this technique has been demonstrated on a polar InGaN epitaxial layer and nonpolar InGaN/GaN quantum wells. SNOM measurements have allowed revealing a number of phenomena, such as the band potential fluctuations and their correlation to the surface morphology, spatial nonuniformity of the radiative and nonradiative lifetimes, as well as the extended band nature of localized states. The combination of different modes enabled measurements of the ambipolar carrier diffusion and its anisotropy.
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| 4. |
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| 5. |
- Pasiskevicius, Valdas, et al.
(författare)
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Spatial and Temporal Coherence in Optical Parametric Devices Pumped with Multimode Beams
- 2018
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Ingår i: Lithuanian Journal of Physics. - : Lithuanian Physical Soc. - 1648-8504 .- 2424-3647. ; 58:1, s. 62-75
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the emergence of spatial and temporal coherence for the fields in the noncritical nondegenerate parametric second-order down-conversion process pumped with low spatial and temporal coherence beams. It is shown that in this scenario, which is of considerable practical importance, the parametric gain in the near field breaks down into an ensemble of mutually incoherent beamlets containing parametric waves. The field generated in a single beamlet is fully spatially coherent. The size of such coherent parametric gain regions is governed by the near-field spatial coherence radius of the pump, which also acts as a parameter, restraining the linear diffraction of the parametric waves generated in the nonlinear interaction. Furthermore, we experimentally demonstrate how the spatial and temporal coherence can be substantially enhanced by manipulating the spatial field correlation of the multilongitudinal and multi-transversal mode pump.
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| 6. |
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| 7. |
- Ruseckas, J., et al.
(författare)
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Electron transmission through graphene monolayer-bilayer junction : An analytical approach
- 2012
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Ingår i: Lithuanian Journal of Physics. - : Lithuanian Physical Society. - 1648-8504. ; 52:1, s. 70-80
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Tidskriftsartikel (refereegranskat)abstract
- A junction of monolayer and bilayer graphene nanoribbons is investigated using the tight-binding approximation. An external potential is applied on the bilayer graphene layers to control the electronic transport properties of the junction. The reflection and transmission probabilities for an incident electron at the junction are analytically calculated. The dependence of the reflection probability on the external potential, the wave vector of the incident electron and the width of the nanoribbon are evaluated.
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| 8. |
- Tamuliene, J., et al.
(författare)
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Investigations of neutral radical molecules suitable for quantum information processing
- 2007
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Ingår i: Lithuanian Journal of Physics. - : Lithuanian Academy of Sciences. - 1648-8504. ; 47:2, s. 137-142
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Tidskriftsartikel (refereegranskat)abstract
- Neutral radical molecules as qubit systems for quantum information processing are described and the application of quantum chemistry methods in search of suitable radicals is outlined. An exemplifying calculation of the relevant magnetic properties of neutral radicals is presented and the suitability of these compounds as building blocks for a quantum computing device based on self-assembled monolayer of radicals is assessed.
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