The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform

Gysbert Setten - One of the best experts on this subject based on the ideXlab platform.

  • Transforming growth factor-alpha is a Constant Component of human tear fluid
    Graefe's Archive for Clinical and Experimental Ophthalmology, 1994
    Co-Authors: Gregory Schultz, Gysbert Setten
    Abstract:

    Growth factors are known as a family of polypeptides with powerful influences on angiogenesis, tumor growth and wound healing. Transforming growth factor-alpha (TGF-α) and epidermal growth factor (EGF) are structurally related peptides which bind to the same receptor, EGF-R, and also exert similar effects. EGF is a natural Component of human tears, and ocular disease leads to decreased concentrations in tear fluid. Using a sensitive radioimmunoassay we investigated whether TGF-α is also to be considered a natural Component of tear fluid and in which concentrations it occurs. All of 46 tear fluid samples from 24 volunteers contained TGF-α. The mean concentration was 161.4 pg TGF-α/ml (SD 11.6 pg). No statistically significant correlation was found between tear fluid flow and TGF-α concentration in the sample. However, the concentration of TGF-α in tear fluid decreased significantly with increasing total time of tear fluid collection ( P = 0.002). TGF-α levels in samples collected from males ( n =16) appeared to be higher (mean 247.0 pg/ml, SD 15.3 pg/ml) than in those from females ( n =30; mean 180.0 pg/ml, SD 8.5 pg/ml; P = 0.05). No correlation was found between the age of the individuals and the concentration of TGF-α in their tear fluid. The findings show that TGF-α is, like EGF, a Constant Component of human tear fluid. The dependence of TGF-α concentration on tear fluid flow and the physiological importance of its presence for corneal integrity and ocular surface physiology, however, require further investigation.

R Kaszynski - One of the best experts on this subject based on the ideXlab platform.

  • non zero initial conditions in filters of the Constant Component
    Instrumentation and Measurement Technology Conference, 2005
    Co-Authors: R Kaszynski
    Abstract:

    The paper presents the possibility of introduction of nonzero initial conditions in filters to shorten the transient state. The carried out analysis of the output signal y(t) with the initial conditions y(0)ne0 and y(0)ne0, y'(0) ne0 shows that the transient state depends only on the variable Component occurring in the filtered signal. The performed simulations allow to judge with a prescribed accuracy how the transient state shortens due to introduction of the non-zero initial conditions for various amounts of the variable Component

  • the parametric filter of signal Constant Component
    International Symposium on Circuits and Systems, 2001
    Co-Authors: R Kaszynski
    Abstract:

    A filter of Constant Component with spectral-response characteristic having pass-band narrowed to frequency /spl omega/=0 and stop-band (with /spl alpha/ tolerance) limited by frequency /spl Omega/ is proposed. Under such filtering assumptions, different possibilities of synthesis for filters with Constant and variable parameters arise. As an evaluation index of the Constant Component filter, the product of transient time (with /spl alpha/ tolerance), operational time and power of filter spectral response characteristic in the frequency band /spl omega/ from 0 to infinity is assumed. The improvement of filter quality (based on well-known filters with Constant parameters) was required in making the parameters of filters variable. The assumed changing parameters functions secure filtering determined by spectral requirements.

  • ISCAS (1) - The parametric filter of signal Constant Component
    ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196), 1
    Co-Authors: R Kaszynski
    Abstract:

    A filter of Constant Component with spectral-response characteristic having pass-band narrowed to frequency /spl omega/=0 and stop-band (with /spl alpha/ tolerance) limited by frequency /spl Omega/ is proposed. Under such filtering assumptions, different possibilities of synthesis for filters with Constant and variable parameters arise. As an evaluation index of the Constant Component filter, the product of transient time (with /spl alpha/ tolerance), operational time and power of filter spectral response characteristic in the frequency band /spl omega/ from 0 to infinity is assumed. The improvement of filter quality (based on well-known filters with Constant parameters) was required in making the parameters of filters variable. The assumed changing parameters functions secure filtering determined by spectral requirements.

  • Stability of parametric, analog low-pass filters
    1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467), 1
    Co-Authors: R Kaszynski
    Abstract:

    The paper presents the necessity and potential possibilities of an introduction of time-varying functions /spl omega//sub 0/(t) and /spl beta/(t) instead of Constant functions /spl omega//sub 0/ and /spl beta/ in the second order building elements of the structure of low-pass filters and Constant Component filters. The need of shortening of the settling time requires, according to the principle of indeterminacy, varying in time the filter parameters. This, in turn, may destabilise the system. In the paper, the stability conditions are defined for the second order parametric system which can be used as a building element of low-pass or Constant Component filters. It is shown that stability of higher order parametric filters can be examined as Constant parameter filters if lim/sub t/spl rarr//spl infin///spl omega//sub 0/(t)=0.

Shawn P. Macauley - One of the best experts on this subject based on the ideXlab platform.

  • Growth factors in human tear fluid and in lacrimal glands.
    Advances in experimental medicine and biology, 1994
    Co-Authors: Gysbert-b Van Setten, Gregory S. Schultz, Shawn P. Macauley
    Abstract:

    EGF has been shown to be a Constant Component of human tear fluid. Its concentration depends on the actual tear fluid flow, as shown for other proteins secreted by the lacrimal gland. This organ has also been considered to be the origin of tear fluid EGF and immunohistochemical evidence for this hypothesis was found. During corneal disease the concentration of EGF in tear fluid considerably decreases to levels even lower than those found during short time stimulation of reflex tearing. Other members of the EGF family, such as TGF-alpha, have considerable similarity with the EGF molecule and even bind to the same receptor. Currently it is thought that TGF-alpha may be, in certain phases of cell life, even more important in the regulation of cell metabolism than EGF. In the present study we have investigated the presence of TGF-alpha in tear fluid and the lacrimal gland. The initial results presented here, show for the first time that TGF-alpha like EGF, seems to be Constant Component of human tear fluid and to originate, at least partially, from the lacrimal gland.

Konstantin V. Zhukovsky - One of the best experts on this subject based on the ideXlab platform.

  • Influence of a Constant magnetic field on the radiation of a planar undulator
    Moscow University Physics Bulletin, 2009
    Co-Authors: G. Dattoli, V. V. Mikhailin, Konstantin V. Zhukovsky
    Abstract:

    The influence of a Constant magnetic field on the radiation of a planar undulator is studied analytically with the use of generalized Bessel functions. The behavior of on-axis radiation intensity in the undulator and the influence of a magnetic field on off-axis radiation are investigated. The critical magnitude of the Constant Component of the magnetic field, which has a significant effect on the motion of electrons in the undulator, is calculated analytically. The examples of several planar undulators are discussed, and the influence of the Earth’s magnetic field on their spectrum is evaluated.

  • Undulator Radiation in a Periodic Magnetic Field with a Constant Component
    Journal of Applied Physics, 2008
    Co-Authors: G. Dattoli, V. V. Mikhailin, Konstantin V. Zhukovsky
    Abstract:

    We present an analytical investigation of radiation emitted by an electron moving in a planar undulator with a Constant magnetic field Component added to the periodic one. In order to calculate the spectrum and angular distribution of radiation, we use the technique of generalized Bessel functions. In particular, this method is effectively applied for the study of the influence of the Constant magnetic field on the undulator radiation emitted both along and off its axis. The analytical formulation of the effect of the weak Constant field enables us to estimate its critical magnitude that may produce a significant distortion in the undulator radiation distributions.

Gysbert-b Van Setten - One of the best experts on this subject based on the ideXlab platform.

  • Growth factors in human tear fluid and in lacrimal glands.
    Advances in experimental medicine and biology, 1994
    Co-Authors: Gysbert-b Van Setten, Gregory S. Schultz, Shawn P. Macauley
    Abstract:

    EGF has been shown to be a Constant Component of human tear fluid. Its concentration depends on the actual tear fluid flow, as shown for other proteins secreted by the lacrimal gland. This organ has also been considered to be the origin of tear fluid EGF and immunohistochemical evidence for this hypothesis was found. During corneal disease the concentration of EGF in tear fluid considerably decreases to levels even lower than those found during short time stimulation of reflex tearing. Other members of the EGF family, such as TGF-alpha, have considerable similarity with the EGF molecule and even bind to the same receptor. Currently it is thought that TGF-alpha may be, in certain phases of cell life, even more important in the regulation of cell metabolism than EGF. In the present study we have investigated the presence of TGF-alpha in tear fluid and the lacrimal gland. The initial results presented here, show for the first time that TGF-alpha like EGF, seems to be Constant Component of human tear fluid and to originate, at least partially, from the lacrimal gland.