The interaction forces between particles have been studied in a 3D plasma cluster under weak exte... more The interaction forces between particles have been studied in a 3D plasma cluster under weak external confinement. A suitable combination of dc and rf applied to a small electrode provided gravity compensation, uniform over dimensions much larger than the cluster itself. The forces acting on the particles could be reconstructed due to unique three-dimensional diagnostics, which allow us to obtain coordinates and velocities of all the particles simultaneously. The measurements yield a maximum (external) confinement force of 1.4 x 10(-15)N and interparticle force that is repulsive at short distances and attractive at larger distances, with a maximum attractive force of 2.4 X 10(-14)N at particle separation 195 microm.
The theory of dust particle oscillations in the plasma sheath is presented, taking into account p... more The theory of dust particle oscillations in the plasma sheath is presented, taking into account particle charging kinetics and neutral gas friction. Effects of ''regular'' and stochastic charge variations are considered. It is shown that whilst regular variations generally enhance the damping of horizontally propagating dust lattice waves, they can also cause an instability in the vertical oscillations of single particles. The stochastic charge variations, if sufficiently strong, result in exponential growth of the mean energy of both types of oscillations.
2013 Abstracts IEEE International Conference on Plasma Science (ICOPS), 2013
ABSTRACT form only given. Since the discovery of the bactericidal action of cold atmospheric plas... more ABSTRACT form only given. Since the discovery of the bactericidal action of cold atmospheric plasma (CAP) researchers also wanted to know its effects on human cells. As there are a huge number of the different used plasma devices the results have a wide range. Several studies on wound healing and other diseases were started and had already first results. But to learn more about mechanisms which are involved and influenced, experiments have to be done in cell cultures. As most of the laboratories are working with cancer cell lines in their cell cultures it was consequential to test the effect of CAP on them. And of course there are again certain distinctions in the behaviour of for example brain tumour cells and ovarian cancer cells. There were some publications in which it is described that CAP can selectively kill cancer cells. Controls were cell lines that are declared as “normal”. But in this context “normal” means only “not cancer cells”. This cell lines are also immortalised for the convenient use in cell cultures and remain an artificial model that cannot be transferred 1:1 to real organisms. In cooperation with the department of Dermatology we were able to establish a primary culture model of human dermal fibroblast of ex vivo skin samples. This is a first step to discover the effects of CAP on cells that were not immortalised or modified otherwise. First results of the CAP treatment of ex vivo human dermal fibroblasts in the bactericidal range of CAP are presented. Cell viability and apoptosis were substance of investigation as well as cell cycle distribution and cell migration.
We study the onset and characteristics of vortices in complex (dusty) plasmas using two-dimension... more We study the onset and characteristics of vortices in complex (dusty) plasmas using two-dimensional simulations in a setup modeled after the PK-3 Plus laboratory. A small number of microparticles initially self-arranges in a monolayer around the void. As additional particles are introduced, an extended system of vortices develops due to a nonzero curl of the plasma forces. We demonstrate a shear-thinning effect in the vortices. Velocity structure functions and the energy and enstrophy spectra show that vortex flow turbulence is present that is in essence of the "classical" Kolmogorov type.
The introduction of low temperature plasma technology to medical research and to the healthcare a... more The introduction of low temperature plasma technology to medical research and to the healthcare arena in general is set to revolutionise the way we cure diseases. This innovative medium offers a valid and advantageous replacement of traditional chemical-based medications. Its application in the inactivation of pathogens in particular, avoids the recurrent problem of drug resistant microorganisms. This is the first book dedicated exclusively to the emerging interdisciplinary field of plasma medicine. The opening chapters discuss plasmas and plasma chemistry, the fundamentals of non-equilibrium plasmas and cell biology. The rest of the book is dedicated to current applications, illustrating a plasma-based approach to wound healing, electrosurgery, cancer treatment and even dentistry. The text provides a clear and integrated introduction to plasma technology and has been devised to answer the needs of researchers from different communities. It will appeal to graduate students and physi...
Monthly Notices of the Royal Astronomical Society, 2009
We continue the analysis of non-Gaussianities in the CMB by means of the scaling index method (SI... more We continue the analysis of non-Gaussianities in the CMB by means of the scaling index method (SIM, Räth, Schuecker & Banday 2007) by applying this method on the single Q-, V-, W-bands and the co-added VW-band of the 5-year data of the Wilkinson Microwave Anisotropy Probe (WMAP). We compare each of the results with 1000 Monte Carlo simulations mimicing the Gaussian properties of the best fit ΛCDM-model. Based on the scaling indices, scale-dependent empirical probability distributions, moments of these distributions and χ 2-combinations of them are calculated, obtaining similar results as in the former analysis of the 3-year data: We derive evidence for non-Gaussianity with a probability of up to 97.3% for the mean when regarding the KQ75-masked full sky and summing up over all considered length scales by means of a diagonal χ 2-statistics. Looking at only the northern or southern hemisphere of the galactic coordinate system, we obtain up to 98.5% or 96.6%, respectively. For the standard deviation, these results appear as 95.6% for the full sky (99.7% north, 89.4% south) and for a χ 2-combination of both measurements as 97.4% (99.1% north, 95.5% south). We obtain larger deviations from Gaussianity when looking at seperate scale lengths. By performing an analysis of rotated hemispheres, we detect an obvious asymmetry in the data. In addition to these investigations, we present a method of filling the mask with Gaussian noise to eliminate boundary effects caused by the mask. With the help of this technique, we identify several local features on the map, of which the most significant one turns out to be the well-known cold spot. When excluding all these spots from the analysis, the deviation from Gaussianity increases, which shows that the discovered local anomalies are not the reason of the global detection of non-Gaussianity, but actually were damping the deviations on average. Our analyses per band and per year suggest, however, that it is very unlikely that the detected anomalies are due to foreground effects.
Journal of the American College of Cardiology, 1996
S-Poster 247A and 48 h. The patients were dasoitied a¢cordtug to WHO-¢dtmia as AMI or norvAML The... more S-Poster 247A and 48 h. The patients were dasoitied a¢cordtug to WHO-¢dtmia as AMI or norvAML The non-AMI group was further divided into those with and without minor myocardial damage (MMD) based on Tn-T and CK-MB. The infarct siZe was classified as "major" or "minor according to peak CK-MB level. 50 patients were used to train the NN and 38 patients (test set) wore used for the evaluation. In the test set the levels of the three biochemical markers were assessed successively for each time point by the three physicians and the NN, respectively. The physicians, but not the NN had access to the ECG at admission. The NN predlcitad "major/minor" MI after a mean of 33 minutes with a naris. = 1.0 and spe¢.= 0.80 for'major" MI; the physidens after 181 minutes with a sens.= 0.83 and spsc. =0.93. Concfusions: Neural netwod~ might be a useful support for the early diagnnsts/exdusion of AMI and prediction of infarct size.
The problem of resonant scattering of charged particles in a turbulent plasma is described in ter... more The problem of resonant scattering of charged particles in a turbulent plasma is described in terms of a simplified diffusion coefficient which allows a good quantitative estimate to be made of D r (pitch angle diffusion coefficient) and K• (spatial diffusion coefficient) for a general case of a wave k vector distribution, which is anisotropic and not necessarily field-aligned. Since the diffusion coefficient depends very strongly on the spectral form (i.e., k vector distribution) of the power in the magnetic fluctuations, it is important to be able to quantify K• for such a general distribution of k vectors, in order to make meaningful comparison w•th observations. The simplified expression derived here for the diffusion coefficient takes advantage of the fact that the quasi-linear theory gives an analytic expression in all those cases where the wave k vector distribution is a delta function. The full k vector distribution is represented as the sum of two weighted delta function approximations, one of which is parallel to the average magnetic field Bo and the other parallel to the direction of maximum k vector density A. The component parallel to Bo turns out to be very important when the k vector distribution is very asymmetric, i.e., the angle between A and Bo is large. The simplified expression for the pitch angle diffusion coefficient is D r = (q/•mc)•'(1tz"){1/8gBP(fB) f •q, doo•/9 + l/2g,• Y-•.,,__ •øøP(nf ,,)J,,"[n(1-#")•/" tan X//z]/z"f,•-y(2•r-dco•)/ (1-9}, where q, m, c, •, 9/'y, and/• are the particle charge, mass, velocity of light, dimensionless particle energy, gyrofrequency, and cosine of particle pitch angle, respectively. In principle, one can use any functional dependence of the k vector density distribution g(O, c•), but for illustration purposes this paper uses the simplest form, i.e., g(O, qb) = [1Dr(C + 2)](1 + C sin 0 s•n qb). The axis of anisotropy A is at an angle X to the magnetic field direction, and thus gs = (1 + C cos X)/r(C + 2) and gA = (1 + C)Dr(C + 2). Here C < 1 expresses the size of the anisotropy. The terms fB andfA are the Doppler-shifted resonance frequencies along the axes A and B. Thus fs = (gt/2r'ywu)[(v ß v,• + and fa = [(v .A + I cos x)/cos xl, where v a is the Alfv•n velocity, v the plasma velocity, and w the particle velocity. The term P(f) is the power spectrum of the magnetic fluctuations at frequency f, door is the weighting factor for the B and A components of the diffusion coefficient (dcos is calculated in the text), and J,,(Z) is the ordinary Bessel function of order n and argument Z. The two-component description is derived in this paper, and the results are applied to the solar cavity by using the theory of V51k et al. (1974). DERIVATION OF THE MOMENTUM DIFFUSION COEFFICIENT General. The general expression for the momentum diffusion coefficient of energetic charged particles in a varying magnetic field, where the fluctuations are Alfv6n waves, was derived by ViSlk et al. [ 1974]. For a static random field, see also Kennel and Engelmann [ 1966], Lerche [ 1968], Hasselmann and Wibberenz [1968], and Kaiser et al. [1973]. Since we are interested in waves propagating with an asymmetric k vector distribution, we shall employ here the result of ViSlk et al. [1974]: :,1.., z where D• is the momentum diffusion coefficient parallel to Bo
The coordinate system generally used to describe the structure of solar-particle profiles over th... more The coordinate system generally used to describe the structure of solar-particle profiles over the polar caps is based on invariant latitude and magnetic local time. By using trajectory integrations in a model geomagnetic field a new coordinate system is developed that is not based on internal geomagnetic-field components alone but also takes into account the currents flowing in the magnetopause and the neutral sheet. It is shown that the new coordinate system is more relevant for the interpretation of high-latitude energetic-particle data than the old system and that its use makes it possible to calculate reconnection rates and scattering mean free paths in the tail. In a companion paper the results of the calculations performed here are applied to observations first to decide which magnetosphere model (open or diffusive) is appropriate and second to use the solar-particle data for making measurements of important magnetospheric parameters.
A theory is presented for the dynamics of dust particles in an incompressible turbulent fluid. Gr... more A theory is presented for the dynamics of dust particles in an incompressible turbulent fluid. Grain-gas coupling occurs through friction forces that are proportional to the mean grain velocity relative to the gas. This test particle theory is applied to the case of a Kolmogoroff spectrum in a protostellar cloud. The mean turbulence induced grain velocity and the mean turbulent relative velocity of two grains are calculated. Whereas the former should determine the dust scale height, grain-grain collisions are influenced by the latter. For a resonable strength of the turbulence, the mean induced relative velocity of two particles turns out to be at least as large as the corresponding terminal velocity difference during gravitational settling.
The interaction of the accreting mass and the X-ray radiation of a spherically accreting neutron ... more The interaction of the accreting mass and the X-ray radiation of a spherically accreting neutron star is described by a dicrete-time dynamical model. Its main feature consists of a nonlinear feedback mechanism between mass accretion and escaping radiation. The model is studied with respect to its stability properties and its astrophysical implications. As a function of time, the authors obtain
Thermal plasmas have been commonly used in medical applications such as plasma ablation and blood... more Thermal plasmas have been commonly used in medical applications such as plasma ablation and blood coagulation. Newer developments show that plasmas can be generated with ion temperatures close to room temperature: these non-thermal or so-called cold atmospheric plasmas (CAPs) therefore open up a wide range of further biomedical applications. Based on the understanding of the bactericidal, virucidal and fungicidal properties of CAPs, information about the effects of CAP on mucosal cells and tissue is still lacking. Therefore this study focuses on the interaction of CAP with healthy head and neck mucosal cells on a molecular level. To analyse this interaction in detail, fresh tissue samples from healthy nasal and pharyngeal mucosa were harvested during surgery, assembled to a three-dimensional tissue culture model (mini organ cultures) and treated with CAP for different treatment times. Effects on the viability, necrosis induction and mutagenic activity were evaluated with the trypan blue exclusion test, Annexin-V/PI staining and alkaline microgel electrophoresis (comet assay). Trypan blue exclusion test revealed that the CAP treatment significantly decreases the cell viability for all tested treatment times (5, 10, 30, 60 and 120 s; p < 0.05), but only a treatment time of 120 s showed a cytotoxic effect as the viability dropped below 90%. Annexin-V/PI staining revealed a significant increase in necrosis in CAP treated pharyngeal tissue cultures for treatment times of 60 and 120 s (p < 0.05). For nasal tissue this effect was already detected for a 30 s treatment (p < 0.05). Comet assay analysis showed no mutagenic effects after exposure to CAP.
Diagnostic methods are developed to measure the microparticle charge Q and two plasma parameters,... more Diagnostic methods are developed to measure the microparticle charge Q and two plasma parameters, electron temperature T e , and ion density n i , in the main plasma region of a dusty plasma. Using video microscopy to track microparticles yields a resonance frequency, which along with a charging model allows an estimation of Q and T e. Only measurements of microparticle position and velocity are required, unlike other methods that use measurements of T e and plasma parameters as inputs. The resonance frequency measurement can also be used with an ion drag model to estimate n i. These methods are demonstrated using a single-layer dusty plasma suspension under microgravity conditions.
The interaction forces between particles have been studied in a 3D plasma cluster under weak exte... more The interaction forces between particles have been studied in a 3D plasma cluster under weak external confinement. A suitable combination of dc and rf applied to a small electrode provided gravity compensation, uniform over dimensions much larger than the cluster itself. The forces acting on the particles could be reconstructed due to unique three-dimensional diagnostics, which allow us to obtain coordinates and velocities of all the particles simultaneously. The measurements yield a maximum (external) confinement force of 1.4 x 10(-15)N and interparticle force that is repulsive at short distances and attractive at larger distances, with a maximum attractive force of 2.4 X 10(-14)N at particle separation 195 microm.
The theory of dust particle oscillations in the plasma sheath is presented, taking into account p... more The theory of dust particle oscillations in the plasma sheath is presented, taking into account particle charging kinetics and neutral gas friction. Effects of ''regular'' and stochastic charge variations are considered. It is shown that whilst regular variations generally enhance the damping of horizontally propagating dust lattice waves, they can also cause an instability in the vertical oscillations of single particles. The stochastic charge variations, if sufficiently strong, result in exponential growth of the mean energy of both types of oscillations.
2013 Abstracts IEEE International Conference on Plasma Science (ICOPS), 2013
ABSTRACT form only given. Since the discovery of the bactericidal action of cold atmospheric plas... more ABSTRACT form only given. Since the discovery of the bactericidal action of cold atmospheric plasma (CAP) researchers also wanted to know its effects on human cells. As there are a huge number of the different used plasma devices the results have a wide range. Several studies on wound healing and other diseases were started and had already first results. But to learn more about mechanisms which are involved and influenced, experiments have to be done in cell cultures. As most of the laboratories are working with cancer cell lines in their cell cultures it was consequential to test the effect of CAP on them. And of course there are again certain distinctions in the behaviour of for example brain tumour cells and ovarian cancer cells. There were some publications in which it is described that CAP can selectively kill cancer cells. Controls were cell lines that are declared as “normal”. But in this context “normal” means only “not cancer cells”. This cell lines are also immortalised for the convenient use in cell cultures and remain an artificial model that cannot be transferred 1:1 to real organisms. In cooperation with the department of Dermatology we were able to establish a primary culture model of human dermal fibroblast of ex vivo skin samples. This is a first step to discover the effects of CAP on cells that were not immortalised or modified otherwise. First results of the CAP treatment of ex vivo human dermal fibroblasts in the bactericidal range of CAP are presented. Cell viability and apoptosis were substance of investigation as well as cell cycle distribution and cell migration.
We study the onset and characteristics of vortices in complex (dusty) plasmas using two-dimension... more We study the onset and characteristics of vortices in complex (dusty) plasmas using two-dimensional simulations in a setup modeled after the PK-3 Plus laboratory. A small number of microparticles initially self-arranges in a monolayer around the void. As additional particles are introduced, an extended system of vortices develops due to a nonzero curl of the plasma forces. We demonstrate a shear-thinning effect in the vortices. Velocity structure functions and the energy and enstrophy spectra show that vortex flow turbulence is present that is in essence of the "classical" Kolmogorov type.
The introduction of low temperature plasma technology to medical research and to the healthcare a... more The introduction of low temperature plasma technology to medical research and to the healthcare arena in general is set to revolutionise the way we cure diseases. This innovative medium offers a valid and advantageous replacement of traditional chemical-based medications. Its application in the inactivation of pathogens in particular, avoids the recurrent problem of drug resistant microorganisms. This is the first book dedicated exclusively to the emerging interdisciplinary field of plasma medicine. The opening chapters discuss plasmas and plasma chemistry, the fundamentals of non-equilibrium plasmas and cell biology. The rest of the book is dedicated to current applications, illustrating a plasma-based approach to wound healing, electrosurgery, cancer treatment and even dentistry. The text provides a clear and integrated introduction to plasma technology and has been devised to answer the needs of researchers from different communities. It will appeal to graduate students and physi...
Monthly Notices of the Royal Astronomical Society, 2009
We continue the analysis of non-Gaussianities in the CMB by means of the scaling index method (SI... more We continue the analysis of non-Gaussianities in the CMB by means of the scaling index method (SIM, Räth, Schuecker & Banday 2007) by applying this method on the single Q-, V-, W-bands and the co-added VW-band of the 5-year data of the Wilkinson Microwave Anisotropy Probe (WMAP). We compare each of the results with 1000 Monte Carlo simulations mimicing the Gaussian properties of the best fit ΛCDM-model. Based on the scaling indices, scale-dependent empirical probability distributions, moments of these distributions and χ 2-combinations of them are calculated, obtaining similar results as in the former analysis of the 3-year data: We derive evidence for non-Gaussianity with a probability of up to 97.3% for the mean when regarding the KQ75-masked full sky and summing up over all considered length scales by means of a diagonal χ 2-statistics. Looking at only the northern or southern hemisphere of the galactic coordinate system, we obtain up to 98.5% or 96.6%, respectively. For the standard deviation, these results appear as 95.6% for the full sky (99.7% north, 89.4% south) and for a χ 2-combination of both measurements as 97.4% (99.1% north, 95.5% south). We obtain larger deviations from Gaussianity when looking at seperate scale lengths. By performing an analysis of rotated hemispheres, we detect an obvious asymmetry in the data. In addition to these investigations, we present a method of filling the mask with Gaussian noise to eliminate boundary effects caused by the mask. With the help of this technique, we identify several local features on the map, of which the most significant one turns out to be the well-known cold spot. When excluding all these spots from the analysis, the deviation from Gaussianity increases, which shows that the discovered local anomalies are not the reason of the global detection of non-Gaussianity, but actually were damping the deviations on average. Our analyses per band and per year suggest, however, that it is very unlikely that the detected anomalies are due to foreground effects.
Journal of the American College of Cardiology, 1996
S-Poster 247A and 48 h. The patients were dasoitied a¢cordtug to WHO-¢dtmia as AMI or norvAML The... more S-Poster 247A and 48 h. The patients were dasoitied a¢cordtug to WHO-¢dtmia as AMI or norvAML The non-AMI group was further divided into those with and without minor myocardial damage (MMD) based on Tn-T and CK-MB. The infarct siZe was classified as "major" or "minor according to peak CK-MB level. 50 patients were used to train the NN and 38 patients (test set) wore used for the evaluation. In the test set the levels of the three biochemical markers were assessed successively for each time point by the three physicians and the NN, respectively. The physicians, but not the NN had access to the ECG at admission. The NN predlcitad "major/minor" MI after a mean of 33 minutes with a naris. = 1.0 and spe¢.= 0.80 for'major" MI; the physidens after 181 minutes with a sens.= 0.83 and spsc. =0.93. Concfusions: Neural netwod~ might be a useful support for the early diagnnsts/exdusion of AMI and prediction of infarct size.
The problem of resonant scattering of charged particles in a turbulent plasma is described in ter... more The problem of resonant scattering of charged particles in a turbulent plasma is described in terms of a simplified diffusion coefficient which allows a good quantitative estimate to be made of D r (pitch angle diffusion coefficient) and K• (spatial diffusion coefficient) for a general case of a wave k vector distribution, which is anisotropic and not necessarily field-aligned. Since the diffusion coefficient depends very strongly on the spectral form (i.e., k vector distribution) of the power in the magnetic fluctuations, it is important to be able to quantify K• for such a general distribution of k vectors, in order to make meaningful comparison w•th observations. The simplified expression derived here for the diffusion coefficient takes advantage of the fact that the quasi-linear theory gives an analytic expression in all those cases where the wave k vector distribution is a delta function. The full k vector distribution is represented as the sum of two weighted delta function approximations, one of which is parallel to the average magnetic field Bo and the other parallel to the direction of maximum k vector density A. The component parallel to Bo turns out to be very important when the k vector distribution is very asymmetric, i.e., the angle between A and Bo is large. The simplified expression for the pitch angle diffusion coefficient is D r = (q/•mc)•'(1tz"){1/8gBP(fB) f •q, doo•/9 + l/2g,• Y-•.,,__ •øøP(nf ,,)J,,"[n(1-#")•/" tan X//z]/z"f,•-y(2•r-dco•)/ (1-9}, where q, m, c, •, 9/'y, and/• are the particle charge, mass, velocity of light, dimensionless particle energy, gyrofrequency, and cosine of particle pitch angle, respectively. In principle, one can use any functional dependence of the k vector density distribution g(O, c•), but for illustration purposes this paper uses the simplest form, i.e., g(O, qb) = [1Dr(C + 2)](1 + C sin 0 s•n qb). The axis of anisotropy A is at an angle X to the magnetic field direction, and thus gs = (1 + C cos X)/r(C + 2) and gA = (1 + C)Dr(C + 2). Here C < 1 expresses the size of the anisotropy. The terms fB andfA are the Doppler-shifted resonance frequencies along the axes A and B. Thus fs = (gt/2r'ywu)[(v ß v,• + and fa = [(v .A + I cos x)/cos xl, where v a is the Alfv•n velocity, v the plasma velocity, and w the particle velocity. The term P(f) is the power spectrum of the magnetic fluctuations at frequency f, door is the weighting factor for the B and A components of the diffusion coefficient (dcos is calculated in the text), and J,,(Z) is the ordinary Bessel function of order n and argument Z. The two-component description is derived in this paper, and the results are applied to the solar cavity by using the theory of V51k et al. (1974). DERIVATION OF THE MOMENTUM DIFFUSION COEFFICIENT General. The general expression for the momentum diffusion coefficient of energetic charged particles in a varying magnetic field, where the fluctuations are Alfv6n waves, was derived by ViSlk et al. [ 1974]. For a static random field, see also Kennel and Engelmann [ 1966], Lerche [ 1968], Hasselmann and Wibberenz [1968], and Kaiser et al. [1973]. Since we are interested in waves propagating with an asymmetric k vector distribution, we shall employ here the result of ViSlk et al. [1974]: :,1.., z where D• is the momentum diffusion coefficient parallel to Bo
The coordinate system generally used to describe the structure of solar-particle profiles over th... more The coordinate system generally used to describe the structure of solar-particle profiles over the polar caps is based on invariant latitude and magnetic local time. By using trajectory integrations in a model geomagnetic field a new coordinate system is developed that is not based on internal geomagnetic-field components alone but also takes into account the currents flowing in the magnetopause and the neutral sheet. It is shown that the new coordinate system is more relevant for the interpretation of high-latitude energetic-particle data than the old system and that its use makes it possible to calculate reconnection rates and scattering mean free paths in the tail. In a companion paper the results of the calculations performed here are applied to observations first to decide which magnetosphere model (open or diffusive) is appropriate and second to use the solar-particle data for making measurements of important magnetospheric parameters.
A theory is presented for the dynamics of dust particles in an incompressible turbulent fluid. Gr... more A theory is presented for the dynamics of dust particles in an incompressible turbulent fluid. Grain-gas coupling occurs through friction forces that are proportional to the mean grain velocity relative to the gas. This test particle theory is applied to the case of a Kolmogoroff spectrum in a protostellar cloud. The mean turbulence induced grain velocity and the mean turbulent relative velocity of two grains are calculated. Whereas the former should determine the dust scale height, grain-grain collisions are influenced by the latter. For a resonable strength of the turbulence, the mean induced relative velocity of two particles turns out to be at least as large as the corresponding terminal velocity difference during gravitational settling.
The interaction of the accreting mass and the X-ray radiation of a spherically accreting neutron ... more The interaction of the accreting mass and the X-ray radiation of a spherically accreting neutron star is described by a dicrete-time dynamical model. Its main feature consists of a nonlinear feedback mechanism between mass accretion and escaping radiation. The model is studied with respect to its stability properties and its astrophysical implications. As a function of time, the authors obtain
Thermal plasmas have been commonly used in medical applications such as plasma ablation and blood... more Thermal plasmas have been commonly used in medical applications such as plasma ablation and blood coagulation. Newer developments show that plasmas can be generated with ion temperatures close to room temperature: these non-thermal or so-called cold atmospheric plasmas (CAPs) therefore open up a wide range of further biomedical applications. Based on the understanding of the bactericidal, virucidal and fungicidal properties of CAPs, information about the effects of CAP on mucosal cells and tissue is still lacking. Therefore this study focuses on the interaction of CAP with healthy head and neck mucosal cells on a molecular level. To analyse this interaction in detail, fresh tissue samples from healthy nasal and pharyngeal mucosa were harvested during surgery, assembled to a three-dimensional tissue culture model (mini organ cultures) and treated with CAP for different treatment times. Effects on the viability, necrosis induction and mutagenic activity were evaluated with the trypan blue exclusion test, Annexin-V/PI staining and alkaline microgel electrophoresis (comet assay). Trypan blue exclusion test revealed that the CAP treatment significantly decreases the cell viability for all tested treatment times (5, 10, 30, 60 and 120 s; p < 0.05), but only a treatment time of 120 s showed a cytotoxic effect as the viability dropped below 90%. Annexin-V/PI staining revealed a significant increase in necrosis in CAP treated pharyngeal tissue cultures for treatment times of 60 and 120 s (p < 0.05). For nasal tissue this effect was already detected for a 30 s treatment (p < 0.05). Comet assay analysis showed no mutagenic effects after exposure to CAP.
Diagnostic methods are developed to measure the microparticle charge Q and two plasma parameters,... more Diagnostic methods are developed to measure the microparticle charge Q and two plasma parameters, electron temperature T e , and ion density n i , in the main plasma region of a dusty plasma. Using video microscopy to track microparticles yields a resonance frequency, which along with a charging model allows an estimation of Q and T e. Only measurements of microparticle position and velocity are required, unlike other methods that use measurements of T e and plasma parameters as inputs. The resonance frequency measurement can also be used with an ion drag model to estimate n i. These methods are demonstrated using a single-layer dusty plasma suspension under microgravity conditions.
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Papers by G. Morfill