Showing papers by "Bielefeld University published in 1996"
TL;DR: In this paper, the pressure and energy density of the SU(3) gauge theory are calculated on lattices with temporal extent N-tau = 4, 6 and 8 and spatial extent n-sigma = 16 and 32.
817 citations
TL;DR: Results suggest that a right hemispheric network of temporal, together with posterior, cingulate, and prefrontal, areas is engaged in the ecphory of affect-laden autobiographical information.
Abstract: We studied the functional anatomy of affect-laden autobiographical memory in normal volunteers. Using H2 15O positron emission tomography (PET), we measured changes in relative regional cerebral blood flow (rCBF). Four rCBF measurements were obtained during three conditions: REST, i.e.,, subjects lay at rest (for control); IMPERSONAL, i.e., subjects listened to sentences containing episodic information taken from an autobiography of a person they did not know, but which had been presented to them before PET scanning (nonautobiographical episodic memory ecphory); and PERSONAL, i.e., subjects listened to sentences containing information taken from their own past (autobiographical episodic memory ecphory). Comparing IMPERSONAL with REST (nonautobiographical episodic memory ecphory) resulted in relative rCBF increases symmetrically in both temporal lobes including the temporal poles and medial and superior temporal gyri. The same loci, however, with a stronger lateralization to the right hemisphere were activated in the comparison PERSONAL to REST (autobiographical episodic memory ecphory). In addition, the right temporomesial, right dorsal prefrontal, right posterior cingulate areas, and the left cerebellum were activated. A comparison of PERSONAL and IMPERSONAL (autobiographical vs nonautobiographical episodic memory ecphory) demonstrated a preponderantly right hemispheric activation including primarily right temporomesial and temporolateral cortex, right posterior cingulate areas, right insula, and right prefrontal areas. The right temporomesial activation included hippocampus, parahippocampus, and amygdala. These results suggest that a right hemispheric network of temporal, together with posterior, cingulate, and prefrontal, areas is engaged in the ecphory of affect-laden autobiographical information.
802 citations
TL;DR: For instance, this paper found that men within the United States have greater psychological and physiological distress to sexual than to emotional infidelity of their partner, and women have been shown to exhibit more distress to emotional than to sexual infidelity.
Abstract: As predicted by models derived from evolutionary psychology, men within the United States have been shown to exhibit greater psychological and physiological distress to sexual than to emotional infidelity of their partner, and women have been shown to exhibit more distress to emotional than to sexual infidelity Because cross-cultural tests are critical for evolutionary hypotheses, we examined these sex differences in three parallel studies conducted in the Netherlands (N = 207), Germany (N = 200), and the United States (N = 224) Two key findings emerged First, the sex differences in sexual jealousy are robust across these cultures, providing support for the evolutionary psychological model Second, the magnitude of the sex differences varies somewhat across cultures—large for the United States, medium for Germany and the Netherlands Discussion focuses on the evolutionary psychology of jealousy and on the sensitivity of sex differences in the sexual sphere to cultural input
295 citations
TL;DR: The diversity of microorganisms associated with the leaves of the seagrass Halophila stipulacea in the northern Gulf of Elat was examined by culture-independent analysis and sequenced clones were found to be affiliated with a marine snow-associated plastid-like rRNA clone and with a Marine Hyphomonas strain, respectively.
Abstract: The diversity of microorganisms associated with the leaves of the seagrass Halophila stipulacea in the northern Gulf of Elat was examined by culture-independent analysis. Microorganisms were harvested by a sonication treatment for total-community genomic DNA isolation. Oligonucleotides complementary to conserved regions in the 16S rRNA-encoding DNA (rDNA) of bacteria were used for PCR amplification. The 16S rDNA PCR products were subcloned and further characterized by a restriction fragment length analysis termed ARDRA (amplified rDNA restriction analysis). These analyses were carried out after reamplifying the cloned fragments with two primers binding symmetrically to the plasmid immediately on both sides of the cloned insert. Computer-aided clustering was performed after separate restriction analysis with enzymes HinfI and HpaII. By this method, 103 cloned 16S rDNA fragments were clustered into a total of 58 different groups. Sequence analysis of clones with an identical ARDRA pattern confirmed that members of an ARDRA group were closely related to each other. The sequenced clones were found to be affiliated with a marine snow-associated plastid-like rRNA clone and with a marine Hyphomonas strain, respectively. The method applied in this study could be useful for the routine study of other microbial communities of interest.
206 citations
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TL;DR: In this article, the authors argue that proof is an essential characteristic of mathematics and as such should be a key component in mathematics education. Translating this statement into classroom practice is not a simple matter, however, because there have been and remain differing and constantly developing views on the nature and role of proof and on the norms to which it should adhere.
Abstract: Proof is an essential characteristic of mathematics and as such should be a key component in mathematics education. Translating this statement into classroom practice is not a simple matter, however, because there have been and remain differing and constantly developing views on the nature and role of proof and on the norms to which it should adhere.
187 citations
TL;DR: In this article, the traces of baryon number in a high-energy process can reside in a nonperturbative configuration of gluon fields, rather than in the valence quarks.
152 citations
TL;DR: In this article, a nanometer-sized helium droplets were used as an inert substrate on which to form spin-3/2 (quartet state) trimers, which undergo intersystem crossing to the doublet manifold and then dissociation into an atom and a covalently bound singlet dimer.
Abstract: Nanometer-sized helium droplets, each containing about 10 4 helium atoms, were used as an inert substrate on which to form previously unobserved, spin-3/2 (quartet state) alkali trimers. Dispersed fluorescence measurements reveal that, upon electronic excitation, the quartet trimers undergo intersystem crossing to the doublet manifold, followed by dissociation of the doublet trimer into an atom and a covalently bound singlet dimer. As shown by this work, aggregates of spin-polarized alkali metals represent ideal species for the optical study of fundamental chemical dynamics processes including nonadiabatic spin conversion, change of bonding nature, and unimolecular dissociation.
143 citations
TL;DR: Gel'fand triples of test and generalized functionals in Gaussian spaces were constructed and characterized in this article, where the triples were constructed from test functions and generalized functions.
142 citations
TL;DR: In this article, a high-statistics study of the volume and coupling constant dependence of the cumulants of the node distribution is carried out, and it appears that the phase transition of the theory is of first order, contrary to what is generally believed.
128 citations
TL;DR: In this article, a detailed derivation of the Landau-Pomeranchuk-Migdal coherent effect in QED is given, focusing on the specific feature of the Coulomb interaction.
114 citations
TL;DR: Pinnipeds are a group of species for which excellent data on maternal strategies exist and seemed to offer striking patterns of maternal care as well as strong evidence for extreme sexual selection on males and, therefore, promised relatively large and easier to analyze effects of parental investment than many other mammalian groups.
Abstract: Publisher Summary This chapter gives information on the natural history of maternal strategies with focus on data about fitness effects of maternal care in pinnipeds. Pinnipeds are a group of species for which excellent data on maternal strategies exist. Energetic expenditure of mothers for nursing their young is high and in phocids is also highly concentrated in time. Energetics of free-ranging animals have been measured in unusual detail in a number of species. Moreover, sexual size dimorphism is extreme in the best-investigated species. For Northern elephant seals, lifetime reproductive success and its correlation with size have been studied in detail for females as well as for males. Thus, at first sight, the group seemed to offer striking patterns of maternal care as well as strong evidence for extreme sexual selection on males and, therefore, promised relatively large and easier to analyze effects of parental investment than many other mammalian groups. The chapter also focuses on evidence for maternal investment and the relationship between energy expenditure and investment and the evidence for and against differential investment in male and female offspring. It presents the observation of post weaning care in pinnipeds for which it is not clear if investment is involved at all.
TL;DR: In this article, it was shown that the H-colouring problem for fixed digraphs admits a homomorphism if and only if there exists an oriented tree which is homomorphic to the digraph but not to H.
Abstract: Let H be a fixed digraph. We consider the H-colouring problem, i.e., the problem of deciding which digraphs G admit a homomorphism to H. We are interested in a characterization in terms of the absence in G of certain tree-like obstructions. Specifically, we say that H has tree duality if, for all digraphs G, G is not homomorphic to H if and only if there is an oriented tree which is homomorphic to G but not to H. We prove that if H has tree duality then the H-colouring problem is polynomial. We also generalize tree duality to bounded treewidth duality and prove a similar result. We relate these duality concepts to the notion of the X-property studied by Gutjahr, Welzl, and Woeginger. We then focus on the case when H itself is an oriented tree. In fact, we are particularly interested in those trees that have exactly one vertex of degree three and all other vertices of degree one or two. Such trees are called triads. We have shown in a companion paper that there exist oriented triads H for which the H-colouring problem is NP -complete. We contrast these with several families of oriented triads H which have tree duality, or bounded treewidth duality, and hence polynomial H-colouring problems. If P 6= NP , then no oriented triad H with an NP -complete H-colouring problem can have bounded treewidth duality; however no proof of this is known, for any oriented triad H. We prove that none of the oriented triads H with NP -complete Hcolouring problems given in the companion paper has tree duality.
TL;DR: Lekking in marine iguanas may represent a ‘hotshot’ phenomenon where small territorial males associate with large males to increase reproductive success.
TL;DR: In this paper, the first in a series of papers dedicated to the structure of Chevalley groups over commutative rings is presented, which is based on the use of their minimal modules.
Abstract: This is the first in a series of papers dedicated to the structure of Chevalley groups over commutative rings. The goal of this series is to systematically develop methods of calculations in Chevalley groups over rings, based on the use of their minimal modules. As an application, we give new direct proofs for normality of the elementary subgroup, description of normal subgroups and similar results due to E. Abe, G. Taddei, L. N. Vaserstein, and others, as well as some generalizations. In this first part we outline the whole project, reproduce construction of Chevalley groups and their elementary subgroups, recall familiar facts about the elementary calculations in these groups, and fix a specific choice of the structure constants.
TL;DR: Bis(2,4,6-tri-tert-butylphenyl)germylene (1), which had been reported to undergo an insertion of the germanium atom into a C−H bond of an otert butyl group at room temperature, was found to be qui...
TL;DR: In this article, an extension of the distribution spaces conventionally used in Gaussian analysis is defined, characterized by analytic properties of S-transforms, allowing for a calculus based on the Wick product.
Abstract: We define an extension of the distribution spaces conventionally used in Gaussian analysis. This space, characterized by analytic properties of S-transforms, allows for a calculus based on the Wick product. We indicate some of its features.
TL;DR: One-loop off-shell contributions to the three-gluon vertex were calculated in an arbitrary covariant gauge and in arbitrary space-time dimensions, including quark-loop contributions with massless quarks as mentioned in this paper.
Abstract: One-loop off-shell contributions to the three-gluon vertex are calculated, in an arbitrary covariant gauge and in arbitrary space-time dimensions, including quark-loop contributions (with massless quarks). It is shown how one can get the results for all on-shell limits of interest directly from the general off-shell expression. The corresponding general expressions for the one-loop ghost-gluon vertex are also obtained. They allow for a check of consistency with the Ward-Slavnov-Taylor identity. {copyright} {ital 1996 The American Physical Society.}
TL;DR: Relativistic harmonic generation by the scattering of very-high-intensity laser light from fast free electrons is investigated theoretically and it is found, among other results, that at laser intensities higher than, say ${10}^{18}$ W/${\mathrm{cm}}^{2}$, the low-order harmonics are suppressed while the higher-order harmonicics are enhanced.
Abstract: Relativistic harmonic generation by the scattering of very-high-intensity laser light from fast free electrons is investigated theoretically. A general solution for the trajectory of an electron, moving initially with an arbitrary velocity in a light pulse of arbitrary intensity and polarization, is presented. This solution generalizes the classical analysis of Eberly [Progress in Optics, edited by E. Wolf (North-Holland, Amsterdam, 1969), Vol. 7] and that of Sarachik and Schappert [Phys. Rev. D 1, 2738 (1970)] for the trajectory of an electron initially at rest. The result is then applied to the case of effective harmonic generation in a monochromatic, circularly polarized field under three different initial conditions for the electron, namely, (a) electron initially at rest, (b) electron initially moving in the direction of light propagation (and opposite to it), and (c) electron initially crossing the radiation beam at right angles. Angular distributions of the harmonics generated by the scattering process are presented in terms of the power scattering cross section in each case. Effects of increasing the light intensity and/or the initial electron speed and/or direction on the angular distributions are discussed. It is found, among other results, that at laser intensities higher than, say ${10}^{18}$ W/${\mathrm{cm}}^{2}$, the low-order harmonics are suppressed while the higher-order harmonics are enhanced. \textcopyright{} 1996 The American Physical Society.
TL;DR: The phenotypes of defined insertion mutants constructed for each gene also indicate that periplasmic nitrate reductase from R. sphaeroides DSM 158 is a dimeric complex of a 90kDa catalytic subunit and a 15kDa cytochrome c (NAPB), which receives electrons from a membrane‐anchored tetrahaem protein, thus allowing electron flow between membrane andPeriplasm.
Abstract: Summary
The prototrophic bacterium Rhodobacter sphaeroides DSM 158 has a periplasmic nitrate reductase which is induced by nitrate and it is not repressed by ammonium or oxygen. In a Tn5 mutant lacking nitrate reductase activity, transposon insertion is localized in a 1.2 kb EcoRI fragment. A 0.6 kb BamHI-EcoRI segment of this region was used as a probe to isolate, from the wild-type strain, a 6.8 kb Pstl fragment carrying the putative genes coding for the periplasmic nitrate reductase. In vivo protein expression and DNA sequence analysis reveal the presence in this region of three genes, napABC, probably organized in an operon. These genes are required for nitrate reduction, as deduced by mutational and complementation studies. The napA gene codes for a protein with a high homology to the periplasmic nitrate reductase from Alcali-genes eutrophus and, to a lesser extent, to other prokaryotic nitrate reductases and molybdenum-containing enzymes. The napB gene product has two haem c-binding sites and shows a high homology with the cytochrome c-type subunit of the periplasmic nitrate reductase from A. eutrophus. NAPA and NAPB proteins appear to be translated with signal peptides of 29 and 24 residues, respectively, indicating that mature proteins are located in the periplasm. The napC gene codes for a 25 kDa protein with a transmembrane sequence of 17 hydrophobic residues. NAPC has four haem c-binding sites and is homologous to the membrane-bound c-type cytochromes encoded by Pseudomonas stutzeri nirT and Escherichia coli torC genes. The phenotypes of defined insertion mutants constructed for each gene also indicate that periplasmic nitrate reductase from R. sphaeroides DSM 158 is a dimeric complex of a 90kDa catalytic subunit (NAPA) and a 15kDa cytochrome c (NAPB), which receives electrons from a membrane-anchored tetrahaem protein (NAPC), thus allowing electron flow between membrane and periplasm. This nitrate-reducing system differs from the assimilatory and respiratory bacterial nitrate reductases at the level of cellular localization, regulatory properties, biochemical characteristics and gene organization.
Abstract: We establish an Ito formula forC
1 functions of processes whose time reversal are semimartingales and forC
1 functions whose first derivatives are Holder continuous of any parameter and the process comes out from a stochastic flow of homeomorphism.
TL;DR: The high affinity of the MMP‐8 for the triple‐helical heterotrimer and the fast digestion of this collagenous peptide confirm the decisive role of the hemopexin domain in recognition and possibly, partial unfolding of collagen.
TL;DR: A system for the inducible destruction of plant tissues based on the deacetylation of the non-toxic compound N-ac-Pt has been developed and the sanity of the female reproductive part of the male-sterile flowers could be demonstrated by cross-pollination.
Abstract: A system for the inducible destruction of plant tissues based on the deacetylation of the non-toxic compound N-acetyl-L-phosphinothricin (N-ac-Pt) has been developed. The argE gene product of Escherichia coli, representing a N-acetyl-L-ornithine deacetylase was identified to remove the acetyl-group from N-ac-Pt giving the cytotoxic compound L-phosphinothricin (Pt, glufosinate). Transgenic Nicotiana tabacum plants constitutively expressing the argE gene were constructed. No effect of the bacterial N-acetyl-L-ornithine deacetylase on plant growth and reproduction could be traced. However, application of N-ac-Pt on leaves of the transgenic plants led to the formation of necrotic areas due to the release of Pt. Additionally, due to the uptake of the N-ac-Pt by roots, transgenic shoots grown on medium containing N-ac-Pt bleached within 6-7 days and finally died. Untransformed controls showed no reaction to high amounts of N-ac-Pt applied, either under sterile or under unsterile conditions. In order to construct inducible male-sterile plants, the argE coding region was fused to a DNA fragment carrying sequences homologous to the tobacco TA29 promoter, known to function exclusively in the tapetum. Owing to the tapetum-specific expression of the chimeric gene the application of N-ac-Pt led to empty anthers resulting in male-sterile plants. The sanity of the female reproductive part of the male-sterile flowers could be demonstrated by cross-pollination. Without N-ac-Pt treatment the plants turned out to be completely fertile making fertility restoration in the F1 generation superfluous. The system presented is easy to handle and might be applicable to a wide range of crop plants.
TL;DR: In this article, a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 0.003 < x < 0.7 was presented.
TL;DR: The phototrophic non-sulfur purple bacterium Rhodobacter capsulatus is able to fix atmospheric dinitrogen either via a conventional molybdenum nitrogenase or via an alternative iron-only nitrogenase, and its regulation is regulated at the transcriptional level and at the post-translational level.
Abstract: The phototrophic non-sulfur purple bacterium Rhodobacter capsulatus is able to fix atmospheric dinitrogen either via a conventional molybdenum nitrogenase or via an alternative iron-only nitrogenase. At least 53 genes are involved in the synthesis and regulation of these two nitrogenase systems, most of which are clustered in four regions widely spread in the genome. Expression of both nitrogenase systems is regulated at the transcriptional level by NifR1 and NifR2, homologues of NtrC and NtrB, respectively. However, this ntr system is only involved in the regulation of the two nitrogenase systems and the high-affinity molybdenum transport system and is not required for utilization of other N sources such as proline and arginine. In contrast to enteric bacteria, the R. capsulatus NtrC homologue does not act in concert with the alternative sigma factor RpoN (σ54). Nitrogen fixation in R. capsulatus is regulated at the transcriptional level and also at the post-translational level. The draTG gene products are responsible for covalent modification of the dinitrogenase reductases of both nitrogenase systems. In addition, mutations in hvrA, a gene previously described as being responsible for low-light activation of the photosynthetic apparatus, also affect regulation of nitrogen fixation.
TL;DR: The most important aetiological factor in trisomy formation in humans is the maternal age as discussed by the authors, which is the most important determinant of chromosome disjunction in humans.
Abstract: Parental age is the most important aetiological factor in trisomy formation in humans. Cytogenetic studies on germ cells reviewed here imply that (i) 2-4% sperm are aneuploid and 8.6% oocytes from IVF are hyperploid (ii) a paternal age effect may exist, and (iii) oocytes of aged women contain precociously separated chromatids in metaphase II. Trisomy data suggest that most aneuploidy is generated during meiosis I of oogenesis and is maternal age-dependent. Trisomy 18 is unique, originating mostly from maternal meiosis II errors. The extra gonosome in 47, XXY derives mostly from a paternal meiosis I error. Trisomy of individual chromosomes may remain low, linearly rise, or exponentially increase with advanced maternal age. Maternal age related trisomies involve achiasmatic and normochiasmate chromosomes, and chromosomes with disturbed recombination and distally located chiasmata. Hypotheses on the origin of the maternal age effect are critically reviewed. One model is presented that relates to altered cell cycle and protein phosphorylation in oocytes of aged mammals and accounts for most of the observed data in humans and in experimental studies. Aneuploidy may thus involve a predetermined component but is possibly also influenced by extrinsic factors reducing oocyte quality or depleting the oocyte pool precociously. Areas of future research are proposed to elucidate (i) the significance of early disturbances in the prenatal ovary, (ii) parameters diminishing the quality of oocytes in dictyate stage, and (iii) mechanisms enabling oocytes to process all chromosomal configurations successfully during later stages of oogenesis. Studies with newly developed and existing animal models appear indispensable to identify exposures affecting chromosome disjunction during meiosis, especially in the aging female.
TL;DR: The avian nucleus rotundus, a nucleus that appears to be homologous to the inferior/ caudal pulvinar of mammals, is the major target of an ascending retino-tecto-thalamic pathway as mentioned in this paper.
Abstract: The avian nucleus rotundus, a nucleus that appears to be homologous to the inferior/ caudal pulvinar of mammals, is the major target of an ascending retino-tecto-thalamic pathway Further clarification of the inputs to the rotundus and their functional properties will contribute to our understanding of the fundamental role of the ascending tectal inputs to the telencephalon in all vertebrates, including mammals We found that the rotundus contains a massive plexus of glutamic acid decarboxylase (GAD)-immunoreactive axons using antibodies against GAD The cells within the rotundus, however, were not immunoreactive for GAD The retrograde tracer cholera toxin B fragment was injected into the rotundus to establish the location of the afferent neurons and determine the source of the gamma-aminobutyric acid (GABA) inputs into the rotundus In addition to the recognized bilateral inputs from layer 13 of the tectum, we found intense retrograde labeling of neurons within the ipsilateral nuclei subpretectalis (SP), subpretectalis-caudalis (SPcd), interstitio-pretecto-subpretectalis (IPS), posteroventralis thalami (PV), and reticularis superior thalami (RS) All the neurons of the SP, SPcd, IPS, and PV were intensely GAD-immunoreactive The neurons of layer 13 of the tectum were not immunoreactive for GAD Following the destruction of the ipsilateral SP/IPS complex, we found a major reduction in the intensity of the GAD axonal immunoreactivity within the ipsilateral rotundus, but this destruction did not diminish the intensity of the GAD-immunoreactivity within the contralateral rotundus Our studies indicated that the source of the massive GAD-immunoreactive plexus within the rotundus was from the ipsilateral SP, SPcd, IPS, and PV nuclei These nuclei, in turn, received ipsilateral tectal input via collaterals of the neurons of layer 13 in the course of their projections upon the rotundus We suggest that the direct bilateral tecto-rotundal projections are excitatory, whereas the indirect ipsilateral projections from the SP/IPS and PV are mainly inhibitory, possibly acting via a GABA-A receptor
TL;DR: In this article, the authors studied charmonium production in hadron-nucleus collisions through the intermediate next-to-leading Fock space component |(c¯)8gi, formed by a colour octet c¯ c pair and a gluon.
TL;DR: TheAlternative nitrogenase of Rhodobacter capsulatus is expressed only under conditions of nitrogen and molybdenum depletion and dual control occurred at the level of transcription of anfA, which encodes a transcriptional activator specific for the alternative nitrogenase.
Abstract: The alternative nitrogenase of Rhodobacter capsulatus is expressed only under conditions of nitrogen and molybdenum depletion. The analysis of anfA-lacZ fusions demonstrated that this dual control occurred at the level of transcription of anfA, which encodes a transcriptional activator specific for the alternative nitrogenase. The anfA promoter was found to be activated under nitrogen-limiting conditions by NtrC in a sigma54-independent manner. In addition, anfA transcription was repressed by traces of molybdenum. This molybdenum-dependent repression of anfA was released in R. capsulatus mutants carrying either lesions in the high-affinity molybdenum uptake system (modABCD) or a double deletion of mopA and mopB, two genes encoding molybdenum-pterin-binding proteins. The expression of the molybdenum transport system itself was shown to be negatively regulated by molybdenum and, unexpectedly, to be also regulated by NtrC. This finding is in line with the presence of two tandemly arranged DNA motifs located in front of the R. capsulatus mopA-modABCD operon, which are homologous to R. capsulatus NtrC binding sites. Mapping of the transcriptional initiation sites of mopA and anfA revealed promoter sequences exhibiting significant homology to each other but no homology to known prokaryotic promoters. In addition, a conserved DNA sequence of dyad symmetry overlapping the transcriptional initiation sites of mopA and anfA was found. Deletions within this element resulted in molybdenum-independent expression of anfA, indicating that this DNA sequence may be the target of MopA/MopB-mediated repression.
TL;DR: Phosphorylation of transcription factors has been found to be one of the mechanisms regulating their cellular localization, DNA binding and transcription activities for defense gene activation in disease resistance genes and receptors.
TL;DR: In this article, an efficient algorithm to generate regular cubic graphs with small vertex valency is presented, and the running times of a program based on this algorithm and designed to generate cubic graphs are below two natural benchmarks: (a) if N(n) denotes the number of pairwise non-isomorphic cubic objects with n vertices and T (n) the time needed for generating the list of all these objects, then T(n)/N(n)) decreases gradually for the observed values of n.
Abstract: In this paper an efficient algorithm to generate regular graphs with small vertex valency is presented. The running times of a program based on this algorithm and designed to generate cubic graphs are below two natural benchmarks: (a) If N(n) denotes the number of pairwise non-isomorphic cubic graphs with n vertices and T(n) the time needed for generating the list of all these graphs, then T(n)/N(n) decreases gradually for the observed values of n. This suggests that T(n)/N(n) might be uniformly bounded for all n, ignoring the time to write the outputs, but we are unable to prove this and in fact are not confident about it. (b) For programs that generate lists of non-isomorphic objects, but cannot a priori make sure to avoid the generation of isomorphic copies, the time needed to check a randomly ordered list of these objects for being non-isomorphic is a natural benchmark. Since for large lists (n ≥ 22, girth 3) existing graph isomorphism programs take longer to canonically label all of the N(n) graphs than our algorithm takes to generate them, our algorithm is probably faster than any method which does one or more isomorphism test for every graph. © 1996 John Wiley & Sons, Inc.