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Search Results: 1 - 10 of 84457 matches for " Gabry W. Mies "
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Neurophysiological correlates of anhedonia in feedback processing
Gabry W. Mies,Ivo Van den Berg,Ingmar H. A. Franken,Frederik M. Van der Veen
Frontiers in Human Neuroscience , 2013, DOI: 10.3389/fnhum.2013.00096
Abstract: Disturbances in feedback processing and a dysregulation of the neural circuit in which the cingulate cortex plays a key role have been frequently observed in depression. Since depression is a heterogeneous disease, instead of focusing on the depressive state in general, this study investigated the relations between the two core symptoms of depression, i.e., depressed mood and anhedonia, and the neural correlates of feedback processing using fMRI. The focus was on the different subdivisions of the anterior cingulate cortex (ACC). Undergraduates with varying levels of depressed mood and anhedonia performed a time-estimation task in which they received positive and negative feedback that was either valid or invalid (i.e., related vs. unrelated to actual performance). The rostral cingulate zone (RCZ), corresponding to the dorsal part of the ACC, was less active in response to feedback in more anhedonic individuals, after correcting for the influence of depressed mood, whereas the subgenual ACC was more active in these individuals. Task performance was not affected by anhedonia, however. No statistically significant effects were found for depressed mood above and beyond the effects of anhedonia. This study therefore implies that increasing levels of anhedonia involve changes in the neural circuitry underlying feedback processing.
The dielectric behaviour of polycrystalline Ba0.96Na0.04Ti0.96Nb0.04O3 solid solution
W. B?k,M. Gabry,W. Tejchman,F. Starzyk
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The purpose of this work was to measure and investigate dielectric properties of new material, polycrystalline solid solution Ba0.96Na0.04Ti0.96Nb0.04O3 (BNTN4) within the temperature range 153 K-473 K.Design/methodology/approach: The dielectric spectroscopy method has been applied to measure dielectric and electric parameters within the frequencies from 20 Hz to 1 MHz.Findings: The dielectric permittivity(ε’) dependence on temperature (T) within the range of 473 K-225 K consist of two components: the reversly proportional one and the second one in the form of small local, transient peak at about 400 K. The global maximum is frequency dependent and above ~400 K along the T decrease, the dispersion of ε’ is initiated and low frequency dispersion of ε’ prevails below 250 K. Energy losses measure (ε”), correlated with ε’(T), is generally shifted towards lower T values. Its frequency dependence undergoes inversion which develops with T decrease and is initiated at about 370 K. The whole temperature induced phase transition turned out to be of relaxor kind and diffused process. The detailed analysis of this transition and its features was performed.Research limitations/implications: In order to determine the details of polycrystalline structure of BNTN4 new material for modelling of ferroelectric properties the precise X-ray diffraction measurements should be performed as function of T. The nature of ferroelectric - paraelectric (FE - PE) transition diffusive character will be studied by means of dielectric measurements within frequency range 1 MHz-1.8 GHz.Originality/value: The new kind of ferroelectric solid solution (BNTN4) was synthesized. The specific features of this material at low T range involves among others, the T-dependent dispersion of dielectric properties on low T side of broad ε’(T) peak
Structural and dielectric properties of polycrystalline (Ba0.9Sr0.1)TiO3
C. Kajtoch,M. Gabry,W. Tejchman,B. Handke
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: This work is aimed to determination of the influence of Sr – ferroactive substitution on physical properties and character of phase transitions (PT) in barium titanate BaTiO3 (BT).Design/methodology/approach: Polycrystalline samples of BST-10 were prepared by means of calcination method at the ~1600 K. Roentgenogram of BST-10 was made within the angles from 10 deg to 110 deg with the 0.008 deg step. Images of the morphology of the samples were taken by means of electron microscope Philips SEM 525M at room temperature. Dielectric measurements were performed with application of Quatro Cryosystem 4.0 and Agilent Precision LCR meter HP4284A equipped with WinDETA 5.62 software Novocontrol. Measurement were taken under cooling with 2 K/min speed. Measuring electric field frequency was from the range 20 Hz-1 MHz.Findings: Dielectric spectroscopy in the frequency domain was applied to measure complex dielectric permittivity and other dielectric functions of ferroelectric polycrystalline (Ba0.9Sr0.1)TiO3 (BST-10). It was established that 10% substitution of Sr in BST-10 solid solution did not change the character of the phase transitions. The temperatures of the phase transitions were correlated with low temperature of PT in SrTiO3 (ST). Similar properties of Ba and Sr ions were taken into consideration. The dipolar character of solid solution was also observed in paraelectric phase.Practical implications: Obtained results can be used to model the effects of ferroactive and nonferroactive substitutions in the A and B subnets of perovskite ferroelectrics.Originality/value: An attempt to correlate low phase angle values observed in the paraelectric phase of BTS-10 with high dielectric permittivity and the occurrence of polar regions.
Diffused phase transition of polycrystalline (Ba0.80Sr0.20)TiO3
C. Kajtoch,W. B?k,M. Gabry,K. Mroczka
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The purpose of this work was to determinate the influence of the 20% Sr substitutions (in sublattice A) on changes of the character of phase transition (PT) in comparison with pure barium titanate BaTiO3 (BT).Design/methodology/approach: Polycrystalline samples of (Ba0.80Sr0.20)TiO3 (BS20T) were prepared by calcinations method at temperature 1620 K. X-ray measurements were executed from 10 deg to 120 deg with the 0.008 deg step. Images of the morphology of the samples were taken by means of electron microscope Philips SEM 525M at room temperature. Dielectric measurements were performed with application of Quatro Cryosystem 4.0 Agilent Precision LRC meter HP4824A equipped with WinDETA 5.62 software Novocontrol. Measurements were taken under cooling with 2 K/min speed. Measuring electric field frequency was from the range 20 Hz - 1 MHz.Findings: The difference between the value of temperature of structural transition (cubic-tetragonal) equal 310K and the temperature Tm (the temperature of maximum of real part electric permittivity) equal 340 K was affirmed. It was affirmed, that 20% substitution of Sr ions changed the type of phase transition. The transition was strongly diffused (DPT). The polar character of this solid solution was also observed in a broad temperature range (in the paraelectric phase too). It is connected with the occurrence of polar regions (clusters).Research limitations/implications: The results can be used to describe changes of PT in the DPT solid solutions with ferroactive substitutions in sublattice A.Originality/value: Value of this work relies on the experimental examination of the dielectric properties of (Ba0.80Sr0.20)TiO3 (BS20T) solid solution. The temperature of the DPT was calculated. The low value of phase angle is connected with the existence of the polar regions.
Dielectric spectroscopy study of Ba0.98Na0.02Ti0.98Nb0.02O3 ceramics
W. B?k,M. Gabry,C. Kajtoch,K. Stanuch
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The purpose of this work was to investigate dielectric properties of new ceramic solid solution Ba0.98Na0.02Ti0.98Nb0.02O3 (BNTN2) within the temperature range 153 K - 473 K.Design/methodology/approach: The dielectric spectroscopy method was applied to measure frequency and temperature dependence of complex dielectric permittivity, complex admittance, phase angle. The frequency dependence of ac conductivity at constant temperature was analysed as well as reciprocal permittivity and dielectric modulus as functions of temperature and frequency were compared. The Curie-Weiss rule and its generalized formula were applied in outcomes analysis.Findings: The ferroelectric - paraelectric (FE - PE) phase transition occurring in BNTN2 was found as having diffusive nature. In the paraelectric phase at about 400 K the diffusivity of transition step is correlated with the same kind of transition in BaTiO3 (BT) (transition of FE - PE type) and with structural transition occurring in NaNbO3 (NN). Within the temperature range below Tm = 308 K, dependences of dielectric properties of BNTN2 ceramic on temperature and frequency was found as having relaxor type of behaviour.Research limitations/implications: The confirmations of achieved findings will be possible by more precise BNTN2 structure determination by means X-ray diffraction. Also closer explanation of FE - PE phase transition can be performed by dielectric measurements within broader frequency range up to 1.8 GHz ( diffusive versus relaxor character of transition).Originality/value: The new solid solution of BNTN2 was prepared. The structure of this material was characterized as dielectrically active and having FE - PE phase transition which was described.
Influence of electric field DC-component on AC-response of ferroelectric powder
F. Starzyk,W. B?k,C. Kajtoch,M. Gabry
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: of this work was to establish whether ac-response of freely stocked micro-granular ferroelectric matter on fringe measuring electric field depends on constant component presence VDC (or DC-Bias).Design/methodology/approach: used involves measurements of effective dielectric permittivity (and other effective dielectric quantities) by means of interdigit dielectrometry. Fringe measuring electric field was applied to BaTiO3 micro-powder by interdigit comb sensor (ICS) Netzsch of Ms25 type. ICS was driven by measuring generator with sinusoidal voltage: v(t)= VDC+VACsin(ωt), within frequency range 20Hz-100kHz and for DC-Bias values ranging as VDC=(0-20)V.Findings: The interdigit dielectrometry was applied to measure complex dielectric permittivity, complex dielectric modulus and others dielectric functions of ferroelectric BaTiO3 powder. The influence of constant component of electric stimulus was investigated in the frequency range 100 kHz to 20 Hz. It was established that in the low frequency range constant component of electric field enhances effective dielectric permittivity, and changes two weak relaxation processes occurring in the ferroelectric micro-granular net. It turned out that effective dielectric complex modulus of this net is most sensitive quantity for application of constant component of electric stimulus.Research limitations/implications: The density solution effect is a source of small effective dielectric permittivity of micro-granular ferroelectric powder (ε’). ε’ values are being enhanced by presence of non zero VDC value. The same effect was established for effective energy loss coefficient (ε”). The two relaxational processes connected with VDC≠0 seems to be a key feature of freely stocked ferroelectric matter.Originality/value: of this work relays on the fact, that this is a first report of the VDC influence on effective dielectric properties of ferroelectric micro-granular matter. It is opening the way to a new approach in modelling of effective dielectric properties of granular matter in nature and powders technology.
Study of phase transition specific in polycrystalline Pb(Cd1/3Nb1/3)O3
C. Kajtoch,W. B?k,F. Starzyk,M. Gabry
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: of this paper was to isolate and attempt to identify experimentally specific features of paraelectric diffused phase of Pb(Cd1/3Nb2/3)O3 (PCN) not reported yet in the literature.Design/methodology/approach: we used was to measure and analyse the temperature and frequency dependence of polarization, energy loss, phase angle and ac-conductivity components.Findings: we have isolated four specific processes visible as specific behaviour of ε’(T, ν); on ε” and phase angle also temperature and frequency dependences and three contributions to ac-conductivity.Practical implications: processes isolated will be used to construct a model of polarizability and energy loss as well as ac-conductivity in diffused paraelectric phase of PCN. Originality/value: of the paper rely on the possibility of experimental verification of temperature induced evolution of polar regions structure and dynamics created in high temperature region of paraelectric phase of PCN.
Dielectric properties of polycrystalline (Ba0.40Sr0.60)O3
C. Kajtoch,W. B?k,M. Gabry,K. Mroczka
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: Purpose of this paper is to qualify of the degree and the causes of broadening of the phase transition in the polycrystalline solid solution (Ba0.40Sr0.60)TiO3 (BS60T).Design/methodology/approach: Polycrystalline samples of (Ba0.40Sr0.60)TiO3 (BS60T) were prepared by calcinations method at temperature 1570K. Images of the morphology of the samples were taken by means of electron microscope Philips SEM 525M at room temperature. Dielectric measurements were performed with application of Quatro Cryosystem 4.0 Agilent Precision LRC meter HP4824A equipped with WinDETA 5.62 software Novocontrol. Measurements were taken under cooling with 2K/min speed. Measuring electric field frequency was from the range 20 Hz - 1 MHz.Findings: The dielectrometry was applied to measure complex dielectric permittivity and other dielectric functions of ferroelectric (BS60T). It was affirmed, that 60% substitution of Sr ions changed the type of phase transition. Weak dependence of temperature Tm=208 K (temperature of maximum electric permittivity ε’) on frequency of the external electric field testifies about diffused character of the phase transition (DPT). The polar character of this material was also observed in the paraelectric phase (to 360 K). This observation is connected with the occurrence of polar clusters in this phase.Research limitations/implications: Results can be used in order to describe the phase transition modifications in the solid solutions with ferroactive substitutions in sublattice B of the perovskite.Originality/value: Value of this work relies on the experimental examination of the electric properties of BS60T solid solution. The low value of phase angle in the paraelectric phase is connected with the occurrence of the polar regions (clusters).
Transplante de fígado
Mies S.
Revista da Associa??o Médica Brasileira , 1998,
Abstract:
ROBOTICS 2010 DEVELOPMENT OF ROBOTICS AND AUTOMATION IN INDUSTRY
MIES, Gerald
Debreceni M?szaki K?zlemények , 2010,
Abstract: The technical development of the industrial robots is one of the most dynamic development fields of the mechanical engineering. The universal applicability and the permanent development of new robot models, size classes and load categories, is the base for this dynamics. The article describes the evolution of the industrial robots being with the first economic applications in the sixties. As in the case of all industry products, the economic efficiently of capital goods is the main accelerating element for the growth. It is the target to describe the different motivations for investment in robot technologies in different decades. At this time, the first applications of robots took place in the lines of business, where human has reached his limits with his physical abilities. The motivation was quality and reproducibility for the use of robots in the eighties. There were about 150 robot manufacturers worldwide at that time. The robot became an industrial series product in the nineties. The efficiency of the application and the price of the robot were responsible for the growing robot population. Since turning of the millennium the technical further development, of for example vision-systems, opens up new fields of applications. Today approximately 10 robot supplier worldwide can follow the speed of the markets.
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