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Biventricular pacing optimization by means of the dyssynchrony parameter
Jurák, Pavel; Leinveber, P.; Halámek, Josef; Plešinger, Filip; Postránecká, T.; Lipoldová, J.; Novák, M.
2016 - anglický
To improve Cardiac Resynchronization Therapy (CRT), different interventricular delay (VVD) settings can be used. However, relatively small VVD induced hemodynamic changes cannot be measured by standard echocardiographic methods. The QRS complex duration (QRSd) is mostly the main criterion. Here we introduce a new dyssynchrony parameter (DYS) that is able to more accurately detect improved electrical synchrony. Methods: 12-lead 5 kHz ECG during 3-10 minute rest period was measured in 46 patients with CRT OFF and CRT ON with VVD 0 ms (CRT0) and -20 ms (CRT20). We detected QRSd and the dyssynchrony parameter DYS as the time difference between 500-1000 Hz averaged envelopes positions in the V1 and V6 leads in the QRS complex region. Results: 32 of 46 patients had a positive CRT response manifested by QRSd shortening and a DYS decrease. 28 of 32 patients had a positive LV pre-excitation effect: additional QRSd shortening of 4.7+/-.9 ms and a DYS decrease of 12.6+/-7.5 ms. The correlation coefficient of QRSd and DYS changes (CRT 0 vs CRT 20) was 0.23 and indicates information diversity. The DYS parameter differs from QRSd and provides a significantly higher response to VVdelay changes (p <; 0.001).
Klíčová slova:
cathode ray tubes; optimization; electrocardiography; cardiology; medical treatment; hemodynamics
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Biventricular pacing optimization by means of the dyssynchrony parameter
To improve Cardiac Resynchronization Therapy (CRT), different interventricular delay (VVD) settings can be used. However, relatively small VVD induced hemodynamic changes cannot be measured by ...
Very low energy STEM/TOF system
Daniel, Benjamin; Radlička, Tomáš; Piňos, Jakub; Frank, Luděk; Müllerová, Ilona
2016 - anglický
Scanning low energy electron microscopes (SLEEMs) have been built at ISI for over 20 years, either by modification of commercially available SEMs with a cathode lens or completely self-built in case of a dedicated ultra-high vacuum scanning low energy electron microscope (UHV SLEEM). Recently, the range of detection methods has been extended\nby a detector for electrons transmitted through ultrathin films and 2D crystals like graphene. For a better understanding of interaction between low energy electrons and solids in general, and the image contrast mechanism in particular, it was considered useful to measure the energy of transmitted electrons. This allows a better comparison with simulations, which suffer from increasing complexity due to a stronger interaction of electrons with the density of states at low energies.
Klíčová slova:
elecvtron microscopy; SLEEM; UHV SLEEM
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Very low energy STEM/TOF system
Scanning low energy electron microscopes (SLEEMs) have been built at ISI for over 20 years, either by modification of commercially available SEMs with a cathode lens or completely self-built in case ...
Bandpass filter for secondary electrons in SEM - simulations
Konvalina, Ivo; Mika, Filip; Krátký, Stanislav; Müllerová, Ilona
2016 - anglický
Scanning electron microscope (SEM) is commonly equipped with a through-the-lens secondary electron detector (TLD). The TLD detector in Magellan 400 FEG SEM works as a bandpass filter for the special setup of potentials of electrodes inside the objective lens, the positive potential on the specimen regulates the energy window of the filter. An energy filtered image contains additional information to that of an unfiltered one. The contrast of the filtered image is changed and new information about the topography and the material can be observed.\nTo understand image contrast formation with TLD detector we traced SEs and BSEs through the three-dimensional (3D) model of included 3D distribution of the electrostatic and magnetic fields. The properties of the bandpass filter were simulated for a working distance (WD) in the range of 1 mm to 3 mm and a primary beam energy (EP) from 1 keV to 10 keV.\nThe 3D electrostatic field of the system was calculated by Simion, magnetic field and raytracing were done using EOD program.
Klíčová slova:
scanning electron microscope; TLD detector
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Bandpass filter for secondary electrons in SEM - simulations
Scanning electron microscope (SEM) is commonly equipped with a through-the-lens secondary electron detector (TLD). The TLD detector in Magellan 400 FEG SEM works as a bandpass filter for the special ...
Bandpass filter for secondary electrons in SEM - experiments
Mika, Filip; Konvalina, Ivo; Krátký, Stanislav; Müllerová, Ilona
2016 - anglický
Bandpass energy filtering using a through-the-lens secondary electron (TLD) detector in a field emission gun SEM (FEG-SEM) has been known over a decade. During energy filtering, image contrast is changed and new information about the material can be observed. Our motivation for this study was to compare theoretical calculations with the experimental data\nof the SE bandpass energy filter in Magellan 400 FEG SEM. The TLD detector works as a bandpass energy filter for the special setup of electrode potentials inside the objective lens, with the positive potential on the specimen regulating the energy window.
Klíčová slova:
electron microscopy; TLD
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Bandpass filter for secondary electrons in SEM - experiments
Bandpass energy filtering using a through-the-lens secondary electron (TLD) detector in a field emission gun SEM (FEG-SEM) has been known over a decade. During energy filtering, image contrast is ...
Scanning very low energy electron microscopy for the characterization of polycrystalline metal samples
Pokorná, Zuzana; Knápek, Alexandr
2016 - anglický
We explored the possibility of a Scanning Electron Microscopy technique for the determination of crystallographic orientation, based on the measurement of the reflectivity of very low energy electrons. Our experiments are based on the concept that in the incident electron energy range 0–30 eV, electron reflectivity can be correlated with the electronic structure of the material, which varies with the local crystallographic orientation of the specimen.\nThe motivation for the development of this technique was to achieve a quick and highresolution means for determining the crystallographic orientation of very small grains in a polycrystalline material. The key limiting factor was the cleanliness of the sample surface and also the geometrical setup of the experiment.
Klíčová slova:
electron microscopy; SEM; crystallographic orientation
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Scanning very low energy electron microscopy for the characterization of polycrystalline metal samples
We explored the possibility of a Scanning Electron Microscopy technique for the determination of crystallographic orientation, based on the measurement of the reflectivity of very low energy ...
Using GPGPU in MR Data Processing
Mikulka, J.; Slíž, J.; Bartušek, Karel
2016 - anglický
The main tissue parameters targeted by MR tomography include, among others, relaxation times T-1 and T-2. This paper focuses on the computation of the relaxation time T-2 measured with the Spin Echo method. The maxima of measured echoes must be interleaved with an exponential function to compute the T2 relaxation. As this procedure needs to be repeated for each pixel of the scanned tissue, the processing of large images then becomes very intensive. This paper introduces the results provided by accelerated computation based on parallelization and carried out with a graphics card. By using the simple method of linear regression, we obtain a processing time of less than 36 ms. In the case of the Levenberg-Marquardt algorithm, the reconstruction was done in 96 ms. This period is at least 900 times shorter than that achievable with professional software.
Klíčová slova:
GPGPU; data processing
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Using GPGPU in MR Data Processing
The main tissue parameters targeted by MR tomography include, among others, relaxation times T-1 and T-2. This paper focuses on the computation of the relaxation time T-2 measured with the Spin Echo ...
New detectors for low-energy BSE
Lalinský, Ondřej; Schauer, Petr; Kučera, M.; Hanuš, M.; Lučeničová, Z.
2016 - anglický
Backscattered electrons (BSE) are mostly used to study the specimen’s topography. Nowadays, low energy (units of keV) electron beam imaging is often necessary for example for the research of nanomaterials, biomaterials or semiconductors. Because BSE detectors are mostly non-accelerating or low-accelerating, electrons with approximately the same energy as primary beam (PB) have to be detected. Therefore, BSE detectors need to become optimized for such low-energy electrons. For the scintillation detectors, the biggest problem probably lies in the scintillator. Semiconductor detectors aren’t studied in this work. Cerium activated bulk single crystals of yttrium aluminium garnet (YAG:Ce)Ce(X):Y(3-X)Al(5)O(12) are widely used as scintillators for the detection of high-energy backscattered electrons (BSE). However, commonly used YAG:Ce single crystal strongly loses its light yield (LY) with the decrease of the PB energy. As possible available alternatives for this application, bulk single crystals of yttrium aluminium perovskite (YAP:Ce) Ce(x)Y(1-X)AlO(3) and CRY018 can be predicted. However, similar LY drop can be expected also with these scintillators.
Klíčová slova:
BSE detector; cathodoluminescence; low-energy electron; scintillator
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
New detectors for low-energy BSE
Backscattered electrons (BSE) are mostly used to study the specimen’s topography. Nowadays, low energy (units of keV) electron beam imaging is often necessary for example for the research of ...
The information depth of backscattered electron imaging
Piňos, Jakub; Mikmeková, Šárka; Frank, Luděk
2016 - anglický
Of the conventional imaging signals in the scanning electron microscope (SEM), the secondary electrons generally reflect surface properties of the sample, while the backscattered electrons (BSE) are capable of providing information about complex properties of the target down to a certain subsurface depth. Contrast mechanisms are combined according to the energy of incident electrons and energy and angular acceptance of BSE detection. In all cases, a question arises concerning the information depth of this mode. No applicable answer provides a definition declaring this depth as that from which we still obtain useful information about the object. We can employ software simulating the electron scattering in solids,\nwhile experimental approaches are also possible. Moreover, two analytic formulas can be found in the literature.
Klíčová slova:
electron microscopy; SEM; BSE
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
The information depth of backscattered electron imaging
Of the conventional imaging signals in the scanning electron microscope (SEM), the secondary electrons generally reflect surface properties of the sample, while the backscattered electrons (BSE) are ...
Secondary electron spectroscopy and energy selective imaging for the engineering of carbon based materials
Rodenburg, C.; Masters, R.; Lidzey, D.; Unčovský, M.; Vystavěl, Tomáš; Mika, Filip
2016 - anglický
That the fine structure of secondary electron emission spectra (SES) from carbon fibres is effected by fibre crystallinity and molecular orientation and linked to engineering materials properties such as modulus was reported over three decades ago. In spite of this\nlongstanding knowledge SES are not yet widely exploited for materials engineering of carbon based materials, probably due to a lack of instrumentation that is suitable to collect SES from beam sensitive materials and also has the capability to visualise, local variation based on SES shape. Thanks to rapid advances in low voltage SEM that offer energy selective imaging, it was recently demonstrated that differences in SES for different carbon based materials can be used to map chemical variations with sub-nanometer resolution when only SE 8 < eV were\nselected to form the SEM images. Such high resolution is not surprising as the implementation of energy filtering in SEMs to improve image resolutions was previously advocated. To fully exploit energy selective imaging for materials engineering the nature of the features in the SES must be determined.
Klíčová slova:
emission spectroscopy; SES
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Secondary electron spectroscopy and energy selective imaging for the engineering of carbon based materials
That the fine structure of secondary electron emission spectra (SES) from carbon fibres is effected by fibre crystallinity and molecular orientation and linked to engineering materials properties such ...
Golden nanoparticle in optical tweezers: influence of shape and orientation on optical trapping
Šiler, Martin; Brzobohatý, Oto; Chvátal, Lukáš; Karásek, Vítězslav; Paták, Aleš; Pokorná, Zuzana; Mika, Filip; Zemánek, Pavel
2016 - anglický
Noble metal nanoparticles (NPs) have attracted increased attention in recent years due to various applications of resonant collective oscillations of free electrons excited with light (plasmon resonance). In contrast to bulk metal materials, where this plasmon resonance frequency depends only on the free electron number density, the optical response of gold and silver NPs can be tuned over the visible and near-infrared spectral region by the size and shape of the NP. Precise and remote placement and orientation of NPs inside cells or tissue would provide another degree of control for these applications. A single focused laser beam – optical tweezers – represents the most frequently used arrangement which provides threedimensional (3D) contact-less manipulation with dielectric objects or living cells ranging in size from tens of nanometers to tens of micrometers. It was believed that larger metal NPs behave as tiny mirrors that are pushed by the light beam radiative force along the direction of beam propagation, without a chance to be confined. However, recently several groups have reported successful optical trapping of gold and silver particles as large as 250 nm. We\noffer an explanation based on the fact that metal nanoparticles naturally occur in various nonspherical\nshapes, and their optical properties differ significantly due to changes in localized plasmon excitation.
Klíčová slova:
NPs; plasmon resonance
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Golden nanoparticle in optical tweezers: influence of shape and orientation on optical trapping
Noble metal nanoparticles (NPs) have attracted increased attention in recent years due to various applications of resonant collective oscillations of free electrons excited with light (plasmon ...
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