804 research outputs found
VIRUSES OF SOME GARLIC ECOTYPES IN CROATIA
Recent, there is increasing demand for autochthonous ecotypes of garlic (Allium sativum L.) in Croatia. Many local ecotypes of garlic are developed due to specific environmental conditions and producer's selection. However, the average yield of garlic is not in the European average range, since the classical vegetative propagation from cloves usually results with virus infections that cause significant yield reduction. Viruses are considered significant garlic’s pathogens. The research was set up to determine infection rate in plant material of different garlic ecotypes grown from cloves in different regions. Plants were collected from commercial fields in Zadar County (coastal part of Croatia) and Vukovar-Srijem County (eastern Croatia) and were tested by enzyme-linked immunosorbent assay (ELISA) on the presence of three viruses: Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV) and Garlic common latent virus (GCLV). As a potential source ofantigen leaf tissue was used and tests were conducted according to manufacturer’s instructions (Bioreba AG, Switzerland). In plants from Zadar County dominant was OYDV, followed by GCLV and LYSV. All tested plants originating from Vukovar-Srijem County were infected with three tested viruses. Out of 316 analyzed plants only 4 (1.3%) showed to be free from viruses included in survey. Plants infected with OYDV showed symptoms of leaf yellowing and reduced growth, while those infected with LYSV expressed yellow stripes. Symptoms were most evident at the beginning of vegetation. Due to high infection rate, deteriorated sanitary status, and increased interest in use and production of local garlic ecotypes, work on sanitary selection will be important part of revitalization program
Evidence for field-induced excitations in low-temperature thermal conductivity of Bi_2Sr_2CaCu_2O_8
The thermal conductivity ,, of Bi_2Sr_2CaCu_2O_8 was studied as a
function of magnetic field. Above 5 K, after an initial decrease,
presents a kink followed by a plateau, as recently reported by Krishana et al..
By contrast, below 1K, the thermal conductivity was found to \emph{increase}
with increasing field. This behavior is indicative of a finite density of
states and is not compatible with the existence of a field-induced fully gapped
state which was recently proposed to describe the
plateau regime. Our low-temperature results are in agreement with recent works
predicting a field-induced enhancement of thermal conductivity by Doppler shift
of quasi-particle spectrum.Comment: 4 pages including 4 eps figures, submitted to Phys. Rev. Let
Conceptual study of non-cylindrical tank for gaseous fuels
The work has been supported by the grant project NCK TN02000009/13 H2C
Structure inhomogeneities, shallow defects, and charge transport in the series of thermoelectric materials K2Bi8−xSbxSe13
The charge transport properties of the low-dimensional thermoelectric materials K2Bi8-xSbxSe13 (02Bi8-xSbxSe13 was analyzed on the basis of the classical semiconductor theory and discussed in the context of recent band calculations. The results suggest that the K2Bi8-xSbxSe13 materials possess coexisting domains with semimetallic and semiconducting characters whose ratio is influenced by the value of x and by local defects. The extent and relative distribution of these domains control the charge transport properties. Electron diffraction experiments performed on samples of K2Bi8-xSbxSe13 with x=1.6 show evidence for such domains by indicating regions with long range ordering of K+/Bi3+ atoms and regions with increased disorder. The semiconducting behavior is enhanced with increasing x (i.e., Sb/Bi ratio) in the composition through a decrease of the semimetallic fraction
Resistivity, Hall effect and Shubnikov-de Haas oscillations in CeNiSn
The resistivity and Hall effect in CeNiSn are measured at temperatures down
to 35 mK and in magnetic fields up to 20 T with the current applied along the
{\it b} axis. The resistivity at zero field exhibits quadratic temperature
dependence below 0.16 K with a huge coefficient of the term (54
cm/K). The resistivity as a function of field shows an
anomalous maximum and dip, the positions of which vary with field directions.
Shubnikov-de Haas (SdH) oscillations with a frequency {\it F} of 100 T
are observed for a wide range of field directions in the {\it ac} and {\it bc}
planes, and the quasiparticle mass is determined to be 10-20 {\it m}.
The carrier density is estimated to be electron/Ce. In a narrow
range of field directions in the {\it ac} plane, where the
magnetoresistance-dip anomaly manifests itself clearer than in other field
directions, a higher-frequency () SdH oscillation is
found at high fields above the anomaly. This observation is discussed in terms
of possible field-induced changes in the electronic structure.Comment: 15 pages, 5 figures, to appear in Phys. Rev. B (15 Sept. 2002 issue
Separation of Quasiparticle and Phononic Heat Currents in YBCO
Measurements of the transverse (k_{xy}) and longitudinal (k_{xx}) thermal
conductivity in high magnetic fields are used to separate the quasiparticle
thermal conductivity (k_{xx}^{el}) of the CuO_2-planes from the phononic
thermal conductivity in YBa_2Cu_3O_{7-\delta}. k_{xx}^{el} is found to display
a pronounced maximum below T_c. Our data analysis reveals distinct transport
(\tau) and Hall (\tau_H) relaxation times below T_c: Whereas \tau is strongly
enhanced, \tau_H follows the same temperature dependence as above T_c
Temperature-dependent anisotropy in MgB as inferred from measurements on polycrystals
We present data on temperature-dependent anisotropy of the upper critical
field of MgB obtained from the analysis of measurements on high purity, low
resistivity polycrystals. The anisotropy decreases in a monotonic fashion with
increase of temperature
Optimization Methods in Emotion Recognition System
Emotions play big role in our everyday communication and contain important information. This work describes a novel method of automatic emotion recognition from textual data. The method is based on well-known data mining techniques, novel approach based on parallel run of SVM (Support Vector Machine) classifiers, text preprocessing and 3 optimization methods: sequential elimination of attributes, parameter optimization based on token groups, and method of extending train data sets during practical testing and production release final tuning. We outperformed current state of the art methods and the results were validated on bigger data sets (3346 manually labelled samples) which is less prone to overfitting when compared to related works. The accuracy achieved in this work is 86.89% for recognition of 5 emotional classes. The experiments were performed in the real world helpdesk environment, was processing Czech language but the proposed methodology is general and can be applied to many different languages
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