"If all your papers are accepted your career will blossom but you have to forget about the Nobel prize"
Alexei A. Abrikosov (Nobel Prize in Physics 2003) during his talk at the APS March Meeting 2004 explaining the happy ending to the 50% rejection rate of his early paper submissions.
J.-C. Wang, T. Foroud, A. L. Hinrichs, N. X. H. Le, S. Bertelsen, J. P. Budde, O. Harari, D. L. Koller, L. Wetherill, A. Agrawal, L. Almasy, A. I. Brooks, K. Bucholz, D. Dick, V. Hesselbrock, E. O. Johnson, S. Kang, M. Kapoor, J. Kramer, S. Kuperman, P. A. F. Madden, N. Manz, N. G. Martin, J. N. McClintick, G. W. Montgomery, J. I. Nurnberger Jr, M. Rangaswamy, J. Rice, M. Schuckit, J. A. Tischfield, J. B. Whitfield, X. Xuei, B. Porjesz, A. C. Heath, H. J. Edenberg, L. J. Bierut, and A. M. Goate:
Several studies have identified genes associated with alcohol-use disorders (AUDs), but the variation in each of these genes explains only a small portion of the genetic vulnerability. The goal of the present study was to perform a genome-wide association study (GWAS) in extended families from the Collaborative Study on the Genetics of Alcoholism to identify novel genes affecting risk for alcohol dependence (AD). To maximize the power of the extended family design, we used a quantitative endophenotype, measured in all individuals: number of alcohol-dependence symptoms endorsed (symptom count (SC)). Secondary analyses were performed to determine if the single nucleotide polymorphisms (SNPs) associated with SC were also associated with the dichotomous phenotype, DSM-IV AD. This family-based GWAS identified SNPs in C15orf53 that are strongly associated with DSM-IV alcohol-dependence symptom counts (P=4.5x10-8, inflation-corrected P=9.4x10-7). Results with DSM-IV AD in the regions of interest support our findings with SC, although the associations were less significant. Attempted replications of the most promising association results were conducted in two independent samples: nonoverlapping subjects from the Study of Addiction: Genes and Environment (SAGE) and the Australian Twin Family Study of AUDs (OZALC). Nominal association of C15orf53 with SC was observed in SAGE. The variant that showed strongest association with SC, rs12912251 and its highly correlated variants (D'=1, r2>=0.95), have previously been associated with risk for bipolar disorder.
D. B. Chorlian, M. Rangaswamy, N. Manz, J.-C. Wang, D. Dick, L. Almasy, L. Bauer, K. Bucholz, T. Foroud, V. Hesselbrock, S. Kang, J. Kramer, S. Kuperman, J. Nurnberger Jr., J. Rice, M. Schuckit, J. Tischfield, H.J. Edenberg, A. Goate, L. Bierut, and B. Porjesz:
Discrete time survival analysis was used to assess the age-specific association of event-related oscillations (EROs) and CHRM2 gene variants on the onset of regular alcohol use and alcohol dependence. The subjects were 2,938 adolescents and young adults ages 12–25. Results showed that the CHRM2 gene variants and ERO risk factors had hazards which varied considerably with age. The bulk of the significant age-specific associations occurred in those whose age of onset was under 16. These associations were concentrated in those subjects who at some time took an illicit drug. These results are consistent with studies which associate greater rates of alcohol dependence among those who begin drinking at an early age. The age specificity of the genetic and neurophysiological factors is consistent with recent studies of adolescent brain development, which locate an interval of heightened vulnerability to substance use disorders in the early to mid teens.
S. J. Kang, M. Rangaswamy, N. Manz, J.-C. Wang, L. Wetherill, T. Hinrichs, L. Almasy, A. Brooks, D. B. Chorlian, D. Dick, V. Hesselbrock, J. Kramer, S. Kuperman, J. Nurnberger Jr, J. Rice, M. Schuckit, J. Tischfield, L.J. Bierut, H. J. Edenberg, A. Goate, T. Foroud, and B. Porjesz:
Event-related oscillations (EROs) represent highly heritable neuroelectric correlates of cognitive processes that manifest deficits in alcoholics and in offspring at high risk to develop alcoholism. Theta ERO to targets in the visual oddball task has been shown to be an endophenotype for alcoholism. A family-based genomewide association study was performed for the frontal theta ERO phenotype using 634 583 autosomal single nucleotide polymorphisms (SNPs) genotyped in 1560 family members from 117 families densely affected by alcohol use disorders, recruited in the Collaborative Study on the Genetics of Alcoholism. Genome-wide significant association was found with several SNPs on chromosome 21 in KCNJ6 (a potassium inward rectifier channel; KIR3.2/GIRK2), with the most significant SNP at P = 4.7 × 10-10). The same SNPs were also associated with EROs from central and parietal electrodes, but with less significance, suggesting that the association is frontally focused. One imputed synonymous SNP in exon four, highly correlated with our top three SNPs, was significantly associated with the frontal theta ERO phenotype. These results suggest KCNJ6 or its product GIRK2 account for some of the variations in frontal theta band oscillations. GIRK2 receptor activation contributes to slow inhibitory postsynaptic potentials that modulate neuronal excitability, and therefore influence neuronal networks.
C. Kamarajan, M. Rangaswamy, N. Manz, D. B. Chorlian, A. K. Pandey, B. N. Roopesh, and B. Porjesz
Recent studies have linked alcoholism with a dysfunctional neural reward system. Although
several electrophysiological studies have explored reward processing in healthy individuals, such
studies in alcohol dependent individuals are quite rare. The present study examines theta
oscillations during reward processing in abstinent alcoholics. The electroencephalogram (EEG)
was recorded in 38 abstinent alcoholics and 38 healthy controls as they performed a single
outcome gambling task which involved outcomes of either loss or gain of an amount (10¢ or 50¢)
that was bet. Event-related theta band (3.0–7.0 Hz) power following each outcome stimulus was
computed using the S-transform method. Theta power at the time window of the outcome-related negativity (ORN) and positivity (ORP) (200–500 ms) was compared across groups and outcome
conditions. Additionally, behavioral data of impulsivity and task performance were analyzed. The
alcoholic group showed significantly decreased theta power during reward processing compared to
M. Kapoor, J. C Wang, S. Bertelsen, K. Bucholz, J. P Budde, A. Hinrichs, A. Agrawal, A. Brooks, D. B Chorlian, D. Dick, V. Hesselbrock, T. Foroud, J. Kramer, S. Kuperman, N. Manz, J. Nurnberger Jr, B. Porjesz, J. P Rice, J. Tischfield, X. Xuei, M. Schuckit, H. J Edenberg, L. J Bierut, and A. Goate
Several genome-wide association and candidate gene studies have linked chromosome 15q24–q25.1 (a region including
the CHRNA5-CHRNA3-CHRNB4 gene cluster) with alcohol dependence, nicotine dependence and smoking-related illnesses
such as lung cancer and chronic obstructive pulmonary disease. To further examine the impact of these genes on the
development of substance use disorders, we tested whether variants within and flanking the CHRNA5-CHRNA3-CHRNB4 gene cluster affect the transition to daily smoking (individuals who smoked cigarettes 4 or more days per week) in a cross
sectional sample of adolescents and young adults from the COGA (Collaborative Study of the Genetics of Alcoholism)
families. Subjects were recruited from families affected with alcoholism (either as a first or second degree relative) and the
comparison families. Participants completed the SSAGA interview, a comprehensive assessment of alcohol and other
substance use and related behaviors. Using the Quantitative trait disequilibrium test (QTDT) significant association was
detected between age at onset of daily smoking and variants located upstream of CHRNB4. Multivariate analysis using a Cox
proportional hazards model further revealed that these variants significantly predict the age at onset of habitual smoking
among daily smokers. These variants were not in high linkage disequilibrium (0.28<r^2<0.56) with variants that have
previously been reported to affect risk for nicotine dependence and smoking related diseases in adults. The data suggests
that an age-associated relationship underlies the association of SNPs in CHRNB4 with onset of chronic smoking behaviors in
adolescents and young adults and may improve genetic information that will lead to better prevention and intervention for
A. K. Pandey, C. Kamarajan, Y. Tang, D. B. Chorlian, B. N. Roopesh, N. Manz, A. Stimus, M. Rangaswamy, and B. Porjesz
In alcoholism research, studies concerning time-locked electrophysiological aspects of response inhibition have concentrated mainly on the P3 component of the event-related potential (ERP). The objective of the present study was to investigate the N2 component of the ERP to elucidate possible brain dysfunction related to the motor response and its inhibition using a Go/NoGo task in alcoholics. The sample consisted of 78 abstinent alcoholic males and 58 healthy male controls. The N2 peak was compared across group and task conditions. Alcoholics showed significantly reduced N2 peak amplitudes compared to normal controls for Go as well as NoGo task conditions. Control subjects showed significantly larger NoGo than Go N2 amplitudes at frontal regions, whereas alcoholics did not show any differences between task conditions at frontal regions. Standardized low resolution electromagnetic tomography analysis (sLORETA) indicated that alcoholics had significantly lower current density at the source than control subjects for the NoGo condition at bilateral anterior prefrontal regions, whereas the differences between groups during the Go trials were not statistically significant. Furthermore, NoGo current density across both groups revealed significantly more activation in bilateral anterior cingulate cortical (ACC) areas, with the maximum activation in the right cingulate regions. However, the magnitude of this difference was much less in alcoholics compared to control subjects. These findings suggest that alcoholics may have deficits in effortful processing during the motor response and its inhibition, suggestive of possible frontal lobe dysfunction.
J. Derringer, R. F. Krueger, N. Manz, B. Porjesz, L. Almasy, E. Bookman, H. J. Edenberg, J. R. Kramer, J. A. Tischfield, GENEVA consortium, and L. J. Bierut
A recent study in a sample of Plains Indians showed
association between eight single nucleotide
polymorphisms (SNPs) located in the SGIP1 gene and
|20)||M. Zlojutro, N. Manz, M. Rangaswamy, X. Xuei, L. Flury-Wetherill, D. Koller, L. J. Bierut, A. Goate, V. Hesselbrock, S. Kuperman, J. Nurnberger Jr., J. P. Rice, M. A. Schuckit, T. Foroud, H. J. Edenberg, B. Porjesz, and L. Almasy
"Genome-wide association study of theta band event-related oscillations identifies serotonin receptor gene HTR7 influencing risk of alcohol dependence"
American Journal of Medical Genetics Part B: Neuropsychiatric Genetics 156 (2011), 44-58
Event-related brain oscillations (EROs) represent highly
heritable neuroelectrical correlates of human perception and
cognitive performance that exhibit marked deficits in patients
with various psychiatric disorders. We report the results of the
first genome-wide association study (GWAS) of an ERO endophenotype -
frontal theta ERO evoked by visual oddball targets
during P300 response in 1,064 unrelated individuals drawn from
a study of alcohol dependence. Forty-two SNPs of the Illumina
HumanHap 1M microarray were selected from the theta ERO
GWAS for replication in family-based samples (N¼1,095), with
four markers revealing nominally significant association. The
most significant marker from the two-stage study is rs4907240
located within ARID protein 5A gene (ARID5A) on chromosome
2q11 (unadjusted, Fisher’s combined P=3.68x10-6).However,
the most intriguing association to emerge is with rs7916403 in
serotoninreceptor geneHTR7onchromosome 10q23 (combined
P=1.53x10-4), implicating the serotonergic system in the
|19)||C. Kamarajan, M. Rangaswamy, Y. Tang, D. B. Chorlian, A. K. Pandey, B. N. Roopesh, N. Manz, R. Saunders, A. T. Stimus, and B. Porjesz
"Dysfunctional reward processing in male alcoholics: An ERP study during a gambling task"
Journal of Psychiatric Research 44 (2010), 576-590
Objective: A dysfunctional neural reward system has been shown to be associated with alcoholism. The
current study aims to examine reward processing in male alcoholics by using event-related potentials
(ERPs) as well as behavioral measures of impulsivity and risk-taking.
|18)||A. C. H. Chen, N. Manz, Y. Tang, M. Rangaswamy, L. Almasy, S. Kuperman, J. Nurnberger Jr, S. J. O'Connor, H. J. Edenberg, M. A. Schuckit, J. Tischfield, T. Foround, L. Bierut, J. Rohrbaugh, J. P. Rice, A. Goate, V. Hesselbrock, and B. Porjesz
"Single Nucleotide Polymorphisms in Corticotropin Releasing Hormone Receptor 1 Gene (CRHR1) Are Associated with Quantitative Traits of Event-Related Potential and Alcohol Dependence"
Alcoholism: Clinical and Experimental Research 34 (2010), 988-996
Background: Endophenotypes reflect more proximal effects of genes than diagnostic categories,
hence providing a more powerful strategy in searching for genes involved in complex psychiatric
disorders. There is strong evidence suggesting the P3 amplitude of the event-related potential
(ERP) as an endophenotype for the risk of alcoholism and other disinhibitory disorders. Recent
studies demonstrated a crucial role of corticotropin releasing hormone receptor 1 (CRHR1) in
the environmental stress response and ethanol self-administration in animal models. The aim of
the present study was to test the potential associations between single-nucleotide polymorphisms
(SNPs) in the CRHR1 gene and the quantitative trait, P3 amplitude during the processing of
visual target signals in an oddball paradigm, as well as alcohol dependence diagnosis.
Methods: We analyzed a sample from the Collaborative Study on the Genetics of Alcoholism
(COGA) comprising 1049 Caucasian subjects from 209 families (including 472 alcohol-dependent
individuals). Quantitative transmission disequilibrium test (QTDT) and family-based association
test (FBAT) were used to test the association, and false discovery rate (FDR) was applied to
correct for multiple comparisons.
We report results on dispersion relations and instabilities of traveling waves in excitable systems. Experiments employ solutions of the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction confined to thin capillary tubes which create a pseudo-one-dimensional system. Theoretical analyses focus on a threevariable reaction-diffusion model that is known to reproduce qualitatively many of the experimentally observed dynamics. Using continuation methods, we show that the transition from normal, monotonic to anomalous, single-overshoot dispersion curves is due to an orbit flip bifurcation of the solitary pulse homoclinics. In the case of "wave stacking'', this anomaly induces attractive pulse interaction, slow solitary pulses, and faster wave trains. For "wave merging'', wave trains break up in the wake of the slow solitary pulse due to an instability of wave trains at small wavelength. A third case, "wave tracking'' is characterized by the non-existence of solitary waves but existence of periodic wave trains. The corresponding dispersion curve is a closed curve covering a finite band of wavelengths.
|16)|| C. Kamarajan, B. Porjesz, M. Rangaswamy, Y. Tang, D. B. Chorlian, A. Padmanabhapillai, R. Saunders, A. K. Pandey, B. N. Roopesh, N. Manz, A. T. Stimus, and H. Begleiter
"Brain signatures of monetary loss and gain: outcome-related potentials in a single outcome gambling task"
Behavioural Brain Research 197 (2009), 62-76
This study evaluates the event-related potential (ERP) components in a single outcome gambling task that involved monetary losses and gains. The participants were 50 healthy young volunteers (25 males and 25 females). The gambling task involved valence (loss and gain) and amount (50¢ and 10¢) as outcomes. The outcome-related negativity (ORN/N2) and outcome-related positivity (ORP/P3) were analyzed and compared across conditions and gender. Monetary gain (compared to loss) and higher amount (50¢ compared to 10¢) produced higher amplitudes and shorter latencies in both ORN and ORP components. Difference wave plots showed that earlier processing (200–400 ms) is dominated by the valence (loss/gain) while later processing (after 400 ms) is marked by the amount (50¢/10¢). Functional mapping using Low Resolution Electromagnetic Tomography (LORETA) indicated that the ORN separated the loss against gain in both genders, while the ORP activity distinguished the 50¢ against 10¢ in males. This study further strengthens the view that separate brain processes/circuitry may mediate loss and gain. Although there were no gender differences in behavioral and impulsivity scores, ORN and ORP measures for different task conditions had significant correlations with behavioral scores. This gambling paradigm may potentially offer valuable indicators to study outcome processing and impulsivity in normals as well as in clinical populations.
|15)|| C. Kamarajan, M. Rangaswamy, D. B. Chorlian, N. Manz, Y. Tang, A. K. Pandey, B. N. Roopesh, A. T. Stimus, and B. Porjesz
"Theta oscillations during the processing of monetary loss and gain: A perspective on gender and impulsivity"
Brain Research 1235 (2008), 45-62
Event-related oscillations (EROs) have proved to be very useful in the understanding of a
variety of neurocognitive processes including reward/outcome processing. In the present
study, theta power (4.0–7.0 Hz) following outcome stimuli in the time window of the N2–P3
complex (200–500 ms) was analyzed in healthy normals (20 males and 20 females) while
performing a gambling task that involved monetary loss and gain. The main aim was to
analyze outcome processing in terms of event-related theta power in the context of valence,
amount, gender, and impulsivity. The S-transform was used for the signal processing of the
ERO data in terms of time–frequency–power. Results from filtered waveforms showed a
partially consistent phase-alignment of the increased theta activity corresponding to N2
and P3 components following the outcome stimuli. Gain conditions produced more theta
power than loss conditions. While there was anterior involvement in both gain and loss,
posterior activation was stronger during gain conditions than during loss conditions.
Front deformation of initially planar excitation waves can be observed in nonplanar media or in spatially heterogeneously illuminated systems. The deformation of propagating reaction–diffusion waves in either of these systems has been investigated earlier separately. Here we present a combination of both heterogeneous systems, which can lead to a compensation of wave deformations. Our theoretical analysis of the evolution of propagating excitation waves, based on the framework of a kinematical theory, shows that the curvature effect can be compensated by illumination. Supporting experiments were performed with the light-sensitive Belousov–Zhabotinsky system.
We report results from experiments with a pseudo-one-dimensional Belousov-Zhabotinsky reaction that employs 1,4-cyclohexanedione as its organic substrate. This excitable system shows traveling oxidation pulses and pulse trains that can undergo complex sequences of propagation failures. Moreover, we present examples for (i) breathing pulses that undergo periodic changes in speed and size and (ii) backfiring pulses that near their back repeatedly generate new pulses propagating in opposite direction.
We report experimental and numerical results on temporal patterns of propagation failures in reactiondiffusion systems. Experiments employ the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction. The propagation failures occur in the frontier region of the wave train and can profoundly affect its expansion speed. The specific rhythms observed vary from simple periodic to highly complex and possibly chaotic sequences. All but the period-1 sequences are found in the transition region between “merging” and “tracking” dynamics, which correspond to wave behavior caused by two qualitatively different types of anomalous dispersion relations.
We present a theoretical analysis of stacking and destacking wave trains in excitable reaction-diffusion systems with anomalous velocity-wavelength dependence. For linearized dispersion relations, kinematic analysis yields an analytical function that rigorously describes front trajectories. The corresponding accelerations have exactly one extremum that slowly decays with increasing pulse number. For subsequent pulses these maxima occur with a lag time equal to the inverse slope of the linearized dispersion curve. These findings are reproduced in experiments with chemical waves in the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction but should be also applicable to step bunching on crystal surfaces and certain traffic phenomena.
We report experimental results on chemical waves in 1,4-cyclohexanedione Belousov-Zhabotinsky systems that obey finite bandwidth dispersion relations. Although solitary pulses and long-wavelength pulse trains are unstable, pacemakers can generate short-wavelength patterns in which fast waves periodically annihilate at the slowly expanding pattern boundary. Along these boundaries, one finds numerous traveling defects that can nucleate rotating spirals which drift outward with the island’s boundary. The drift follows logarithmic spirals and can induce spiral pair annihilation.
We report experimental results obtained from a chemical reaction-diffusion system in which wave propagation is limited to a finite band of wavelengths and in which no solitary pulses exist. Wave patterns increase their size through repeated annihilation events of the frontier pulse that allow the succeeding pulses to advance farther. A related type of wave dynamics involves a stable but slow frontier pulse that annihilates subsequent waves in front-to-back collisions. These so-called merging dynamics give rise to an unexpected form of spiral wave nucleation. All of these phenomena are reproduced by a simple, three-species reaction-diffusion model that reveals the importance of the underlying anomalous dispersion relation.
Meandering spiral waves are observed in the 1,4-cyclohexanedione Belousov-Zhabotinsky (CHD-BZ) reaction at very low concentrations (3-35 mM) of the organic substrate. The spiral tips describe hypocycle-like trajectories indicating the presence of two main rotation periods and radii. The ratio of these periods approaches 1 for decreasing concentrations of CHD. In this limit, we find Z-shaped trajectories with approximately two lobes. The use of Fe[batho(SO3)2]34-/3- as the BZ catalyst gives rise to extremely long rotation periods (1000-4000 s), and the tip trajectories span large areas of up to 40 mm2. As a result of the absence of gaseous products and the high absorption of the catalyst, this particular system is ideally suited for the investigation of spiral waves in closed, thin-layer systems, such as nonuniformly curved and micropatterned media.
For many years the Belousov–Zhabotinsky reaction has been used to explore the large variety of dynamical behavior of excitation waves. The understanding of chemical waves can be applied to other physical and biological systems. Most theoretical and experimental work has been done in planar media, whereas for nonplanar systems there exist many theoretical but only very few experimental studies. In this article we present a methodology to develop quasi-two-dimensional, nonhomogeneously curved reaction media. These systems can be used to perform experiments on chemical reaction-diffusion processes which occur, for instance, in the Belousov–Zhabotinsky reaction placed in nonplanar geometries.
The dynamic behaviour of spiral waves rotating on surfaces of curved reaction–diffusion systems depends strongly on the curvature of the surface. It was shown in an earlier experiment that a spiral in a Belousov–Zhabotinsky system on a paraboloid drifts to the point of highest Gaussian curvature, as predicted numerically and analytically. Beyond this, theoretical work predicts an increase of the rotation frequency of spiral waves with an increase in the curvature of the system surface (e.g., spirals on different spherical surfaces with decreasing radii). This behaviour leads to an additional term in the function for the rotation frequency proportional to the Gaussian curvature of the system. In this Letter we combine both effects to determine the curvature dependence of the spiral rotation frequency in curved reaction–diffusion systems. On a non-homogeneously curved surface, the spiral tip (the inner end of a spiral) drifts through regions with increasing surface curvature. Measurements of the rotation frequency performed during this propagation verify the predicted effect. The experimental data are confirmed by analytical results in the framework of the kinematic theory.
The evolution of excitation wave fronts in a spatially modulated light-sensitive Belousov-Zhabotinsky system is investigated experimentally and theoretically. The excitation wave propagates in a thin, quasi-twodimensional reaction layer, which is illuminated through a periodical gray level mask. The light-induced differences in excitability and velocity give rise to a temporal and spatial modulation of the initially flat fronts. The experimental front evolution is described in the framework of a kinematical theory as developed earlier for nonuniformly curved systems.
In the literature, different properties of propagating excitation waves on curved surfaces are published. Theoretical papers predicted critical properties of waves on curved surfaces. If an excitation wave propagates in a non-planar system, its geodetic curvature causes a transition from excitable to non-excitable dynamics. In this paper we present first experimental results of the transition in a weakly excitable BZ system which are in good agreement with the theoretical predictions.
We report the formation of stable bound wave packets in a modified Belousov-Zhabotinsky reaction. These densely stacked structures arise from an attractive interaction between oxidation pulses that is not known from the classical Belousov-Zhabotinsky system. The characteristic stacking period increases with the initial concentration of bromate but decreases with cyclohexanedione. Wave stacking can also induce cascades of bunching events in which internally dense but mutually well segregated wave clusters are formed. For different initial concentrations, we observed the apparent merging of waves in front-to-back collisions. All three modes of wave dynamics are analyzed in terms of their dispersion behavior. The dispersion relations proved to be anomalous in each case and revealed the existence of an attractor which induces the formation of stable wave packets. The underlying mechanism has a pure reaction-diffusion character since wave propagation is not affected by fluid convection. At high initial concentrations of ferroin, we detected complex relaxation kinetics which indicate the presence of at least two independent species that control the recovery and hence the dispersion behavior of the medium.
The evolution of an excitation front propagating on a nonuniformly curved surface is considered within the framework of a kinematical model of its motion. For the case of a surface with a periodically modulated curvature an exact solution of the front shape is obtained under the assumption of sufficiently small surface deformation. The results of the theoretical consideration are compared with the experimental data obtained with a modified Belousov-Zhabotinsky reaction in a thin nonuniformly curved layer.
We present experimental results that demonstrate anomalous dispersion in a Belousov-Zhabotinsky system. The reaction is carried out at high concentrations of sulfuric acid and involves 1,4-cyclohexanedione as its organic substrate. The unusual dispersion behavior of this excitable medium induces an attractive interaction between pulses that results in fusion or closed stacking of waves. Experimental results from quasi-onedimensional as well as two-dimensional media are presented. In two-dimensional reaction systems, a complex dependence of the propagation velocity on the relative direction between fronts is found and the formation of spiral defects is observed.
"Untersuchung chemischer Wellen} in der Belousov-Zhabotinsky-Reaktion: räumliche modulierte Systeme und anomale Dispersion" ("Investigation of chemical waves in the Belousov-Zhabotinsky reaction: spatially modulated systems and anomalous dispersion")
Cuvillier Verlag, Göttingen, Germany, pp 210. (ISBN-10: 3898735273) (2002)
"Untersuchung der Dynamik chemischer Erregungswellen in Belousov-Zhabotinsky-Systemen mit anomaler Dispersion" ("Investigation of the dynamic of chemical excitation waves in Belousov-Zhabotinsky systems with anomalous dispersion")
Nova Acta Leopoldina, Neue Folge Suppl. 20 (2006), 103-104
"Untersuchung der Dynamik chemischer Erregungswellen in Belousov-Zhabotinsky-Systemen mit anomaler Dispersion" ("Investigation of the dynamic of chemical excitation waves in Belousov-Zhabotinsky systems with anomalous dispersion")
Nova Acta Leopoldina, Neue Folge Suppl. 19 (2004), 135-137
| A. Honig, N. Manz, A. Paul, S. Röttger und U. Keyser
"Radondiffusion unterschiedlicher Schlauchmaterialien" ("Radon diffusion through different tube materials")
Jahresbericht der Physikalisch-Technischen-Bundesanstalt 1998, 2.6.4 (1999), 250-251