The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform

Horst Rogalla - One of the best experts on this subject based on the ideXlab platform.

  • interference characterization of cryocoolers for a high tc squid based Fetal Heart Monitor
    2002
    Co-Authors: A P Rijpma, M R Bangma, H A Reincke, E G De Vries, H J Holland, H J M Ter Brake, Horst Rogalla
    Abstract:

    The FHARMON-project at the University of Twente aims at a high-Tc SQUID based Fetal Heart Monitor for use in standard clinical environments. Besides the suppression of environmental magnetic noise, the cooling of this Fetal Heart Monitor is an important issue. For maximum flexibility, we intend to apply a closed-cycle cryocooler instead of a liquid nitrogen cryostat. Because of the extreme sensitivity of SQUID magnetometers, the interference caused by the cryocooler is of major importance. This concerns electromagnetic interference (EMI), mechanical vibrations and temperature fluctuations. We have developed measuring techniques to characterize coolers in this respect. The characterization procedures were tested on a Signaal USFA 7058 Stirling cooler and a Leybold RGD210 GM-cooler. In the paper the measuring techniques are described along with interference characteristics of an APD Cryotiger and a Ricor/AirLiquide K535 Stirling cooler. Also, the impact on the design of the Fetal Heart Monitor is considered.

  • cryogenic aspects of a Fetal Heart Monitor based on high tc squids
    Advances in cryogenic engineering, 2000
    Co-Authors: A P Rijpma, M R Bangma, H J M Ter Brake, M J Peters, Horst Rogalla
    Abstract:

    A high-Tc SQUID-based magnetometer system for measuring Fetal Heart activity in standard clinical environments is the goal of the so-called FHARMON project. To lower the threshold for the application of this Fetal Heart Monitor, it should be low-cost and, moreover, simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. In this paper the requirements with respect to the cryogenic system are discussed for this specific application. These include operating temperature (55–80 K), temperature stability (<0.5 K drift in 10 hours), cooling power (<0.5 W), mechanical vibrations, electromagnetic interference and costs (<$US 5000). Next to the requirements, the paper also reviews the most relevant options for the realization of the cryogenic system. In this respect two categories are distinguished: systems incorporating coolers with ‘noisy’ cold heads (e.g. GM and Stirling) versus those using coolers with a low-noise cold head (e.g. pulse tube and JT) requiring respectively long and short thermal interfaces.

Craig V Towers - One of the best experts on this subject based on the ideXlab platform.

  • Fetal Heart Monitor tracing in a pregnancy complicated by a ruptured Fetal vessel on the placenta a case report
    Journal of Reproductive Medicine, 2016
    Co-Authors: Kevin Visconti, Craig V Towers
    Abstract:

    Background This report describes the Fetal Heart rate (FHR) tracing in a pregnancy complicated by antenatal spontaneous rupture of Fetal vessels on the placental surface that resulted in a live birth. Case 36-year-old woman, G2P1001, was being followed with weekly antenatal testing for gestational diabetes type A2 on insulin with possible intrauterine growth restriction. She presented for an office visit at 37.5 weeks' gestation with a complaint of decreased Fetal movement. The FHR pattern demonstrated minimal baseline variability with an occasional spontaneous deceleration not associated with a contraction, an absence of recurrent decelerations, and no accelerations. The antenatal evaluation is discussed, and portions of the FHR tracing and the placental findings at delivery are provided. Conclusion The FHR pattern did not fit with what is usually depicted with uteroplacental insufficiency or umbilical cord entrapment. In addition, even though the fetus is anemic, the process may occur too quickly for a sinusoidal pattern to develop.

  • the Fetal Heart Monitor tracing in pregnancies complicated by a spontaneous umbilical cord hematoma
    Journal of Perinatology, 2009
    Co-Authors: Craig V Towers, C E Juratsch, Thomas J Garite
    Abstract:

    The objective of this study is to present and describe the Fetal Heart rate appearance in pregnancies complicated by an antenatal spontaneous umbilical cord hematoma that resulted in a live birth. Three cases of antenatal spontaneous umbilical cord hematoma are described. All three patients presented with a complaint of decreased Fetal movement. The Fetal Heart Monitor tracings on admission are depicted and discussed. In all three cases, the Fetal Heart rate pattern showed decreased variability with an absence of accelerations. Decelerations were noted but were identified in 25% or less of the contractions and primarily with contractions that exceeded 90 s. Absent accelerations with minimal to absent variability, if caused by uteroplacental insufficiency, usually develop in the presence of recurrent decelerations. Absent accelerations with minimal to absent variability in the absence of recurrent decelerations may suggest other causes including aneuploidy or congenital cardiac or neurologic anomalies. Though rare, spontaneous umbilical cord hematoma can be added to the differential.

  • the Fetal Heart Monitor tracing in pregnancies complicated by Fetal thyrotoxicosis
    American Journal of Perinatology, 2009
    Co-Authors: Craig V Towers, Steven Thomas, Ralph M Steiger
    Abstract:

    Fetal tachycardia caused by the transplacental passage of thyroid stimulating immunoglobulin is well established, but very little information exists regarding the Fetal Heart rate appearance of this form of tachycardia. Two cases of Fetal tachycardia are described in pregnancies complicated by Fetal thyrotoxicosis where maternal thyroid history was unknown at the time of testing. For each pregnancy, the Fetal Heart Monitor tracing is depicted and described. In both cases, the initial Fetal Heart rate pattern demonstrated a sustained baseline of 170 to 180 beats per minute with moderate variability that exhibited accelerations with a lack of decelerations. The tracings were essentially normal except for the baseline rate. When reviewing the differential for Fetal tachycardia presenting in the antenatal period, this pattern is unique to Fetal thyrotoxicosis, especially if the mother is afebrile and there is no history of medication usage that could explain this presentation.

  • influence of carbon monoxide poisoning on the Fetal Heart Monitor tracing a report of 3 cases
    Journal of Reproductive Medicine, 2009
    Co-Authors: Craig V Towers, Vincent A Corcoran
    Abstract:

    BACKGROUND: The diagnosis of carbon monoxide poisoning in the third trimester of pregnancy requires an index of suspicion, and the appearance ofthe Fetal Heart Monitor tracing may help in this regard. CASES: Three cases of third-trimester acute carbon monoxide poisoning occurred. In each pregnancy, the Fetal Heart Monitor tracing on admission was correlated with the maternal carboxyhemoglobin level, and how the pattern changed following the institution of therapy was analyzed. CONCLUSION: In all 3 cases, the initial Fetal Heart rate pattern demonstrated decreased variability with an elevated baseline and an absence of accelerations and decelerations. Within 45-90 minutes of treatment onset, the baseline Fetal Heart rate dropped by 20-40 beats per minute, the variability became moderate, and accelerations occurred. Absent accelerations with minimal variability, if caused by uteroplacental insufficiency, are usually preceded by recurrent decelerations. Absent accelerations with minimal variability in the absence of recurrent decelerations may suggest another cause, of which carbon monoxide intoxication can be added to the differential, especially since this disorder often has nonspecific clinical symptoms.

A P Rijpma - One of the best experts on this subject based on the ideXlab platform.

  • interference characterization of cryocoolers for a high tc squid based Fetal Heart Monitor
    2002
    Co-Authors: A P Rijpma, M R Bangma, H A Reincke, E G De Vries, H J Holland, H J M Ter Brake, Horst Rogalla
    Abstract:

    The FHARMON-project at the University of Twente aims at a high-Tc SQUID based Fetal Heart Monitor for use in standard clinical environments. Besides the suppression of environmental magnetic noise, the cooling of this Fetal Heart Monitor is an important issue. For maximum flexibility, we intend to apply a closed-cycle cryocooler instead of a liquid nitrogen cryostat. Because of the extreme sensitivity of SQUID magnetometers, the interference caused by the cryocooler is of major importance. This concerns electromagnetic interference (EMI), mechanical vibrations and temperature fluctuations. We have developed measuring techniques to characterize coolers in this respect. The characterization procedures were tested on a Signaal USFA 7058 Stirling cooler and a Leybold RGD210 GM-cooler. In the paper the measuring techniques are described along with interference characteristics of an APD Cryotiger and a Ricor/AirLiquide K535 Stirling cooler. Also, the impact on the design of the Fetal Heart Monitor is considered.

  • cryogenic aspects of a Fetal Heart Monitor based on high tc squids
    Advances in cryogenic engineering, 2000
    Co-Authors: A P Rijpma, M R Bangma, H J M Ter Brake, M J Peters, Horst Rogalla
    Abstract:

    A high-Tc SQUID-based magnetometer system for measuring Fetal Heart activity in standard clinical environments is the goal of the so-called FHARMON project. To lower the threshold for the application of this Fetal Heart Monitor, it should be low-cost and, moreover, simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. In this paper the requirements with respect to the cryogenic system are discussed for this specific application. These include operating temperature (55–80 K), temperature stability (<0.5 K drift in 10 hours), cooling power (<0.5 W), mechanical vibrations, electromagnetic interference and costs (<$US 5000). Next to the requirements, the paper also reviews the most relevant options for the realization of the cryogenic system. In this respect two categories are distinguished: systems incorporating coolers with ‘noisy’ cold heads (e.g. GM and Stirling) versus those using coolers with a low-noise cold head (e.g. pulse tube and JT) requiring respectively long and short thermal interfaces.

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

  • interference characterization of cryocoolers for a high tc squid based Fetal Heart Monitor
    2002
    Co-Authors: A P Rijpma, M R Bangma, H A Reincke, E G De Vries, H J Holland, H J M Ter Brake, Horst Rogalla
    Abstract:

    The FHARMON-project at the University of Twente aims at a high-Tc SQUID based Fetal Heart Monitor for use in standard clinical environments. Besides the suppression of environmental magnetic noise, the cooling of this Fetal Heart Monitor is an important issue. For maximum flexibility, we intend to apply a closed-cycle cryocooler instead of a liquid nitrogen cryostat. Because of the extreme sensitivity of SQUID magnetometers, the interference caused by the cryocooler is of major importance. This concerns electromagnetic interference (EMI), mechanical vibrations and temperature fluctuations. We have developed measuring techniques to characterize coolers in this respect. The characterization procedures were tested on a Signaal USFA 7058 Stirling cooler and a Leybold RGD210 GM-cooler. In the paper the measuring techniques are described along with interference characteristics of an APD Cryotiger and a Ricor/AirLiquide K535 Stirling cooler. Also, the impact on the design of the Fetal Heart Monitor is considered.

  • cryogenic aspects of a Fetal Heart Monitor based on high tc squids
    Advances in cryogenic engineering, 2000
    Co-Authors: A P Rijpma, M R Bangma, H J M Ter Brake, M J Peters, Horst Rogalla
    Abstract:

    A high-Tc SQUID-based magnetometer system for measuring Fetal Heart activity in standard clinical environments is the goal of the so-called FHARMON project. To lower the threshold for the application of this Fetal Heart Monitor, it should be low-cost and, moreover, simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. In this paper the requirements with respect to the cryogenic system are discussed for this specific application. These include operating temperature (55–80 K), temperature stability (<0.5 K drift in 10 hours), cooling power (<0.5 W), mechanical vibrations, electromagnetic interference and costs (<$US 5000). Next to the requirements, the paper also reviews the most relevant options for the realization of the cryogenic system. In this respect two categories are distinguished: systems incorporating coolers with ‘noisy’ cold heads (e.g. GM and Stirling) versus those using coolers with a low-noise cold head (e.g. pulse tube and JT) requiring respectively long and short thermal interfaces.

H J M Ter Brake - One of the best experts on this subject based on the ideXlab platform.

  • interference characterization of cryocoolers for a high tc squid based Fetal Heart Monitor
    2002
    Co-Authors: A P Rijpma, M R Bangma, H A Reincke, E G De Vries, H J Holland, H J M Ter Brake, Horst Rogalla
    Abstract:

    The FHARMON-project at the University of Twente aims at a high-Tc SQUID based Fetal Heart Monitor for use in standard clinical environments. Besides the suppression of environmental magnetic noise, the cooling of this Fetal Heart Monitor is an important issue. For maximum flexibility, we intend to apply a closed-cycle cryocooler instead of a liquid nitrogen cryostat. Because of the extreme sensitivity of SQUID magnetometers, the interference caused by the cryocooler is of major importance. This concerns electromagnetic interference (EMI), mechanical vibrations and temperature fluctuations. We have developed measuring techniques to characterize coolers in this respect. The characterization procedures were tested on a Signaal USFA 7058 Stirling cooler and a Leybold RGD210 GM-cooler. In the paper the measuring techniques are described along with interference characteristics of an APD Cryotiger and a Ricor/AirLiquide K535 Stirling cooler. Also, the impact on the design of the Fetal Heart Monitor is considered.

  • cryogenic aspects of a Fetal Heart Monitor based on high tc squids
    Advances in cryogenic engineering, 2000
    Co-Authors: A P Rijpma, M R Bangma, H J M Ter Brake, M J Peters, Horst Rogalla
    Abstract:

    A high-Tc SQUID-based magnetometer system for measuring Fetal Heart activity in standard clinical environments is the goal of the so-called FHARMON project. To lower the threshold for the application of this Fetal Heart Monitor, it should be low-cost and, moreover, simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. In this paper the requirements with respect to the cryogenic system are discussed for this specific application. These include operating temperature (55–80 K), temperature stability (<0.5 K drift in 10 hours), cooling power (<0.5 W), mechanical vibrations, electromagnetic interference and costs (<$US 5000). Next to the requirements, the paper also reviews the most relevant options for the realization of the cryogenic system. In this respect two categories are distinguished: systems incorporating coolers with ‘noisy’ cold heads (e.g. GM and Stirling) versus those using coolers with a low-noise cold head (e.g. pulse tube and JT) requiring respectively long and short thermal interfaces.