ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Depolarisierte Lichtstreuung in Flüssigkeiten mit Wasserstoff-Brückenbindungen (1979)
    Springer
    Colloid & polymer science 257 (1979), S. 1012-1012 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01520741
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The superposition of a temporally incoherent magnetic field inhibits 60 Hz-induced changes in the ODC activity of developing chick embryos (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 19 (1998), S. 53-56 
    Details
    ISSN: 0197-8462
    Keywords: ELF ; ODC ; EMF ; Noise ; embryonic development ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Previously, we have shown that the application of a weak (4 μT) 60 Hz magnetic field (MF) can alter the magnitudes of the ornithine decarboxylase (ODC) activity peaks which occur during gastrulation and neurulation of chick embryos. We report here the ODC activity of chick embryos which were exposed to the superposition of a weak noise MF over a 60 Hz MF of equal (rms strength). In contrast to the results we obtain with a 60 Hz field alone, the activity of ODC in embryos exposed to the superposition of the incoherent and 60 Hz fields was indistinguishable from the control activity during both gastrulation and neurulation. This result adds to the body of experimental evidence which demonstrates that the superposition of an incoherent field inhibits the response of biological systems to a coherent MF. The observation that a noise field inhibits ODC activity changes is consistent with our speculation that MF-induced ODC activity changes during early development may be related to MF-induced neural tube defects at slightly later stages (which are also inhibited by the superposition of a noise field). Bioelectromagnetics 19:53-56, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Dose-response implications of the transient nature of electromagnetic-field-induced bioeffects: Theoretical hypotheses and predictions (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 237-246 
    Details
    ISSN: 0197-8462
    Keywords: windows ; transient response ; chemical reaction model ; rate constant ; transcription ; teratogenesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Data in the literature imply that the relationship between exposure and bio-effect involves more than a simple time integral of the field strength to which the living system has been subjected. Windows - ranges in which the system exhibits enhanced sensitivity - have been reported for power (or field strength), frequency, and the duration of the exposure. In this paper we show that such isolated window effects can be accounted for by recognizing the transient character of the response of the biological system. The principal assumption here is that the direct effect of the field is to increase the rates of production and degradation of mRNA or proteins. In this paper we review and extend the mathematical model that quantifies this. The model predicts that, for a given field strength, certain optimum relatively short duration exposures cause significantly larger bio-effects than exposure for much longer or much shorter times. The thinking embodied in the model should provide a framework for obtaining a meaningful working definition of “effective dose” and for predicting the response of subjects to environmental electromagnetic fields. It should help in deciding the relevant variables in the design and analysis of epidemiological studies. 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130721
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    A simple experiment to study electromagnetic field effects: Protection induced by short-term exposures to 60 Hz magnetic fields The described project's contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH. (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 19 (1998), S. 498-500 
    Details
    ISSN: 0197-8462
    Keywords: chick embryos ; anoxia ; stress proteins ; protective effect ; magnetic field ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Stress proteins are important in protection during cardiac ischemia/reperfusion (cessation and return of blood flow) and are reportedly induced by electromagnetic (EM) fields. This suggests a possible ischemia protection role for EM exposures. To test this, chick embryos (96 h) were exposed to 60 Hz magnetic fields prior to being placed into anoxia. Survival was 39.6% (control), and 68.7% (field-exposed). As a positive control, embryos were heated prior to anoxia (57.6% survival). We conclude that: 1) 60 Hz magnetic field exposures reduce anoxia-induced mortality in chick embryos, comparable to reductions observed following heat stress, and 2) this is a simple and rapid experiment to demonstrate the existence of weak EM field effects. Bioelectromagnetics 19:498-500, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Temporally incoherent magnetic fields mitigate the response of biological systems to temporally coherent magnetic fields (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 399-409 
    Details
    ISSN: 0197-8462
    Keywords: noise ; coherence ; incoherence ; signal to noise ; ornithine decarboxylase ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We have previously demonstrated that a weak, extremely-low-frequency magnetic field must be coherent for some minimum length of time (≍ 10 s) in order to affect the specific activity of ornithine decarboxylase (ODC) in L929 mouse cells. In this study we explore whether or not the superposition of an incoherent (noise) magnetic field can block the bioeffect of a coherent 60 Hz magnetic field, since the sum of the two fields is incoherent. An experimental test of this idea was conducted using as a biological marker the twofold enhancement of ODC activity found in L929 murine cells after exposure to a 60 Hz, 10 μTrms magnetic field. We superimposed an incoherent magnetic noise field, containing frequencies from 30 to 90 Hz, whose rms amplitude was comparable to that of the 60 Hz field. Under these conditions the ODC activity observed after exposure was equal to control levels. It is concluded that the superposition of incoherent magnetic fields can block the enhancement of ODC activity by a coherent magnetic field if the strength of the incoherent field is equal to or greater than that of the coherent field. When the superimposed, incoherent noise field was reduced in strength, the enhancement of ODC activity by the coherent field increased. Full ODC enhancement was obtained when the rms value of the applied EM noise was less than one-tenth that of the coherent field. These results are discussed in relation to the question of cellular detection of weak EM fields in the presence of endogenous thermal noise fields. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250150504
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Amplitude windows and transiently augmented transcription from exposure to electromagnetic fields (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 11 (1990), S. 297-312 
    Details
    ISSN: 0197-8462
    Keywords: ELF fields ; transient response ; chemical-reaction model ; rate constant ; RNA synthesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The exposure of cells to relatively low-intensity, pulsed, low-frequency electromagnetic fields can result in a transient augmentation of mRNA synthesis. Under certain conditions of irradiation, the augmentation is a function of the strength of the electromagnetic field. A linear, multi-step, chemical-reaction model accounts for many of the principal features that are observed in both the time- and intensity-dependent variations of transcriptional effects. The crucial assumption in the model is that the direct effect of electromagnetic fields on exposed cells is an increase in the rate constant that characterizes one of the intermediate sequential reactions in the synthesis of mRNA.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250110406
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Determination of the induced ELF electric field distribution in a two layer in vitro system simulating biological cells in nutrient solution (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 14 (1993), S. 29-39 
    Details
    ISSN: 0197-8462
    Keywords: dosimetry ; magnetic field exposure ; induced current ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In-vitro studies of biological effects of electromagnetic fields are often conducted with cultured cells either in suspension or grown in a monolayer. In the former case, the exposed medium can be assumed to be homogeneous; however, eventually the cells settle to the bottom of the container forming a two layer system with different dielectric and conductive properties. In the present work the effect of this separation on the electric field distribution is calculated and experimentally measured at selected positions for a commonly used exposure configuration. The settled cell suspension is modeled by a well-defined two layer system placed in a rectangular container with the base of the container parallel to the direction of the magnetic field. Theoretical calculations based on numerical techniques are done for various two layer systems with different conductivities in each layer. The agreement between the theoretical calculations and the experimental measurements is within ± 1.5 mV/m, or 10% of the maximum induced field when the conductivity of the lower layer is ten times that of the upper layer. This result is well within experimental error. When the thickness of one of the layers is small compared to the thickness of the other layer, it is found that the electric field distribution is essentially that of the homogeneous case. The latter situation corresponds to a typical cell exposure condition. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250140106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The role of coherence time in the effect of microwaves on ornithine decarboxylase activity (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 14 (1993), S. 395-403 
    Details
    ISSN: 0197-8462
    Keywords: coherence time ; microwave ; amplitude modulation ; ornithine decarboxylase ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Previously, we demonstrated the requirement for a minimum coherence time of an applied, small amplitude (10 μT) ELF magnetic field if the field were to produce an enhancement of ornithine decarboxylase activity in L929 fibroblasts. Further investigation has revealed a remarkably similar coherence time phenomenon for enhancement of ornithine decarboxylase activity by amplitude-modulated 915 MHz microwaves of large amplitude (SAR 2.5 W/kg). Microwave fields modulated at 55, 60, or 65 Hz approximately doubled ornithine decarboxylase activity after 8 h. Switching modulation frequencies from 55 to 65 Hz at coherence times of 1.0 s or less abolished enhancement, while times of 10 s or longer provided full enhancement. Our results show that the microwave coherence effects are remarkably similar to those observed with ELF fields. © 1993 Wiley-Liss. Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250140502
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Superimposing spatially coherent electromagnetic noise inhibits field-induced abnormalities in developing chick embryos (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 105-113 
    Details
    ISSN: 0197-8462
    Keywords: noise ; cooperativity ; signal-to-noise ; embryo development ; abnormalities ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Living cells exist in an electrically noisy environment. This has led to the so-called “signal-to-noise” problem whereby cells are observed to respond to extremely-low-frequency (ELF) exogenous fields that are several orders of magnitude weaker than local endogenous fields associated with thermal fluctuations. To resolve this dilemma, we propose that living cells are affected only by electromagnetic fields that are spatially coherent over their surface. The basic idea is that a significant number of receptors must be simultaneously and coherently activated (biological cooperativity) to produce effects on the biochemical functioning of the cell. However, like all physical detection systems, cells are subject to the laws of conventional physics and can be confused by noise. This suggests that a spatially coherent but temporally random noise field superimposed on a coherent ELF signal will defeat the mechanism of discrimination against noise, and any observed field-induced bioeffects would be suppressed. An experimental test of this idea was conducted using morphological abnormalities in developing chick embryos caused by electromagnetic field exposure as the endpoint. At an impressed noise amplitude comparable to the ELF field strength (but roughly one-thousandth of the thermal noise field), the increased abnormality rate observed with only the ELF field present was reduced to a level essentially the same as for the control embryos. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250150203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    ELF in vitro exposure systems for inducing uniform electric and magnetic fields in cell culture media (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 183-198 
    Details
    ISSN: 0197-8462
    Keywords: dosimetry ; induced electric field ; induced current ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Many in vitro experiments on the biological effects of extremely low frequency (ELF) electromagnetic fields utilize a uniform external magnetic flux density (B) to expose biological materials. A significant number of researchers do not measure or estimate the resulting electric field strength (E) or current density (J) in the sample medium. The magnitude and spatial distribution of the induced E field are highly dependent on the sample geometry and its relative orientation with respect to the magnetic field. We have studied the E fields induced in several of the most frequently used laboratory culture dishes and flasks under various exposure conditions. Measurements and calculations of the E field distributions in the aqueous sample volume in the containers were performed, and a set of simple, quantitative tables was developed. These tables allow a biological researcher to determine, in a straightforward fashion, the magnitudes and distributions of the electric fields that are induced in the aqueous sample when it is subjected to a uniform, sinusoidal magnetic field of known strength and frequency. In addition, we present a novel exposure technique based on a standard organ culture dish containing two circular, concentric annular rings. Exposure of the organ culture dish to a uniform magnetic field induces different average electric fields in the liquid medium in the inner and outer rings. Results of experiments with this system, which were reported in a separate paper, have shown the dominant role of the magnetically induced E field in producing specific biological effects on cells, in vitro. These results emphasize the need to report data about the induced E field in ELF in-vitro studies, involving magnetic field exposures. Our data tables on E and J in standard containers provide simple means to enable determination of these parameters. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...