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ABSTRACT: Homeostasis and development in vertebrates are regulated by cell proliferation, differentiation and death. Permeability of mitochondrial membranes, a decisive feature of apoptosis, is regulated by Bcl-2 family regulators. Protein p53 is able to reduce bcl-2 and promote bax expression. This study focused on the immunohistochemical detection of the expression levels of Bcl-2 family regulators (anti-apoptotic Bcl-2 and Bcl-XL, pro-apoptotic Bcl-Xs and Bax), p53, and PCNA as a marker of proliferation, together with the evaluation of the level of apoptosis in human embryos (anlage of limbs, axial skeleton, metanephros, and intestine). Expression of observed proteins was assessed by a three-step immunohistochemistry and evidenced by the double-staining technique. Apoptosis was detected by the TUNEL technique. This study provided circumstantial evidence of the exclusive role of Bcl-2 and Bcl-XL proteins in the inhibition of apoptosis - only rarely were the Bcl-2/ Bcl-XL positive cells stained by TUNEL. The role of pro-apoptotic members of Bcl-2 family remains ambiguous, as TUNEL positive cells are both Bax/Bcl-Xs positive and negative. This study provided substantial evidence that expression patterns of observed proteins are neither fully explainable by "rheostat" theory, nor are the findings obtained from animal model tissue or cell culture commonly applicable to human embryos.
General Physiology and Biophysics 07/2004; 23(2):209-29. · 1.19 Impact Factor
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ABSTRACT: In this paper, a new current vector control method combined with
an indirect-field-orientation feedforward algorithm is presented for
shaft-sensorless induction motor drives. The new current control
technique is based on the concept that the angular speed and the
magnitude of the stator current vector can be controlled by two stator
voltage components relative to the stator current vector. In the
proposed solution, the current regulators are rotating together with the
stator current vector. The new topology drive has improved low-speed
performance compared to the conventional solutions
IEEE Transactions on Industry Applications 08/2001; · 1.66 Impact Factor
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ABSTRACT: This paper deals with some aspects concerning the implementation
of a sensorless induction motor control for industry applications. The
proposed control method uses an adaptive rotor flux observer and a
suitable adaptation law for the speed estimation. It has been found that
this method is superior to many other methods when the performance
versus complexity criterion is considered. The adaptation law is
obtained by a general one, valid for any induction motor parameter
estimation. A comparison between the floating and the fixed point DSP
implementation of the proposed method is presented. In fact, the
appearance of new and powerful fixed point DSP microcontrollers makes
the fixed point solution very attractive for many industrial
applications, such as retrofits, conveyors control, and a lot of
manufacturing process control. Different algorithm implementation
issues, such as the online computation of the observer gain matrix and
of the discrete motor model are discussed in this paper. Simulation and
experimental results for the two cases (fixed and floating point DSP
implementation) are shown
Power Conversion Conference - Nagaoka 1997., Proceedings of the; 09/1997
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ABSTRACT: In this paper a unified approach to different schemes based on
model reference adaptive systems (MRAS) for speed sensorless field
oriented controlled (FOC) induction motor drives is presented. In the
last few years several solutions belonging to this category have been
proposed. They have different configurations and distinct adaptation
mechanisms, properly chosen in each case. A new, general adaptation
mechanism is presented in the paper. It is derived according to Popov
hyperstability theory and is valid for any adaptive system belonging to
this category, no matter what its configuration is. A general
demonstration for the stability of these adaptive systems is given,
using the Lyapunov stability theorem. This unitary approach allows an
easier comparison and classification of different particular solutions.
The paper focuses on two of the most used configurations. In the first
solution the reference model is the motor and the adaptive one is a
linear state observer, which, in particular, is an extended Luenberger
observer (ELO). In the second solution, both models are rotor flux (or
other quantities) estimators and this scheme is usually known as a model
reference adaptive system (MRAS). The performance of these two schemes
is analyzed starting from their configuration and then compared by
simulations and experimental results
Industry Applications Conference, 1996. Thirty-First IAS Annual Meeting, IAS '96., Conference Record of the 1996 IEEE; 11/1996
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ABSTRACT: The aim of this paper is to show how the performance of a simple
V-I flux estimator for field oriented (FO) controlled drives can be
improved, simply by improving the quality of the input signals (voltages
and currents) and eliminating the offset from the resulting flux signal,
without using sophisticated mathematical methods such as Luenberger
observers, Kalman filters or others. The proposed method requires almost
no increase of the computation time in digital implementation, thus a
cheap processor can be used
Industrial Electronics Society, 1998. IECON '98. Proceedings of the 24th Annual Conference of the IEEE;
