Showing papers by "University of Victoria published in 1999"

Cortisol in teleosts: dynamics, mechanisms of action, and metabolic regulation

Abstract: Cortisol is the principal corticosteriod in teleost fishes and its plasma concentrations rise dramatically during stress. The relationship between this cortisol increase and its metabolic consequences are subject to extensive debate. Much of this debate arises from the different responses of the many species used, the diversity of approaches to manipulate cortisol levels, and the sampling techniques and duration. Given the extreme differences in experimental approach, it is not surprising that inconsistencies exist within the literature. This review attempts to delineate common themes on the physiological and metabolic roles of cortisol in teleost fishes and to suggest new approaches that might overcome some of the inconsistencies on the role of this multifaceted hormone. We detail the dynamics of cortisol, especially the exogenous and endogenous factors modulating production, clearance and tissue availability of the hormone. We focus on the mechanisms of action, the biochemical and physiological impact, and the interaction with other hormones so as to provide a conceptual framework for cortisol under resting and/or stressed states. Interpretation of interactions between cortisol and other glucoregulatory hormones is hampered by the absence of adequate hormone quantification, resulting in correlative rather than causal relationships.

Who Matters to Ceos? An Investigation of Stakeholder Attributes and Salience, Corpate Performance, and Ceo Values

Abstract: Using unique data provided by the CEOs of 80 large U.S. firms, the authors examined relationships among the stakeholder attributes of power, legitimacy, urgency, and salience; CEO values; and corpo...

Mutations in ABC1 in Tangier disease and familial high-density lipoprotein deficiency

Abstract: Genes have a major role in the control of high-density lipoprotein (HDL) cholesterol (HDL-C) levels. Here we have identified two Tangier disease (TD) families, confirmed 9q31 linkage and refined the disease locus to a limited genomic region containing the gene encoding the ATP-binding cassette transporter (ABC1). Familial HDL deficiency (FHA) is a more frequent cause of low HDL levels. On the basis of independent linkage and meiotic recombinants, we localized the FHA locus to the same genomic region as the TD locus. Mutations in ABC1 were detected in both TD and FHA, indicating that TD and FHA are allelic. This indicates that the protein encoded by ABC1 is a key gatekeeper influencing intracellular cholesterol transport, hence we have named it cholesterol efflux regulatory protein (CERP).

Differential Galaxy Evolution in Cluster and Field Galaxies at z ≈ 0.3

Abstract: We measure spectral indexes for 1823 galaxies in the Canadian Network for Observational Cosmology 1 (CNOC1) sample of 15 X-ray luminous clusters at 0.18 5 A] but no [O II] emission [W0(O ) < 5 A], perhaps indicative of recently terminated star formation. The observed fraction of 4.4% ± 0.7% in the cluster sample is an overestimate due to a systematic effect that results from the large uncertainties on individual spectral index measurements. Corrected for this bias, we estimate that K+A galaxies make up only 2.1% ± 0.7% of the cluster sample and 0.1% ± 0.7% of the field. From the subsample of galaxies more luminous than Mr = -18.8 + 5 log h, which is statistically representative of a complete sample to this limit, the corrected fraction of K+A galaxies is 1.5% ± 0.8% in the cluster and 1.2% ± 0.8% in the field. Compared with the z ≈ 0.1 fraction of 0.30%, the fraction of K+A galaxies in the CNOC1 field sample is greater by perhaps a factor of 4, but with only 1 σ significance; no further evolution of this fraction is detectable over our redshift range. We compare our data with the results of PEGASE and GISSEL96 spectrophotometric models and conclude, from the relative fractions of red and blue galaxies with no [O II] λ3727 emission and strong Hδ absorption, that up to 1.9% ± 0.8% of the cluster population may have had its star formation recently truncated without a starburst. However, this is still not significantly greater than the fraction of such galaxies in the field, 3.1% ± 1.0%. Furthermore, we do not detect an excess of cluster galaxies that have unambiguously undergone starbursts within the last 1 Gyr. In fact, at 6.3% ± 2.1%, the A+em galaxies that Poggianti et al. have recently suggested are dusty starbursts are twice as common in the field as in the cluster environment. Our results imply that these cluster environments are not responsible for inducing starbursts; thus, the increase in cluster blue galaxy fraction with redshift may not be a strictly cluster-specific phenomenon. We suggest that the truncation of star formation in clusters may largely be a gradual process, perhaps due to the exhaustion of gas in the galactic disks over fairly long timescales; in this case differential evolution may result because field galaxies can refuel their disks with gas from extended halos, thus regenerating star formation, while cluster galaxies may not have such halos and so continue to evolve passively.

The thermal imprint of galaxy formation on X-ray clusters

Abstract: It is widely believed that structure in the Universe evolves hierarchically—fluctuations in the primordial distribution of matter, amplified by gravity, collapse and merge to form progressively larger systems, culminating in the clusters of galaxies that are observed today. But the observed structure and evolution of X-ray-emitting clusters of galaxies seems to be at odds with this picture1. In particular, clusters and groups with relatively few galaxies, as well as most distant clusters, are substantially fainter in X-rays than predicted by models of hierarchical formation. Here we show that these discrepancies arise because the entropy of the hot diffuse intracluster gas near the centre of the cluster is higher than can be explained by gravitational collapse alone. We argue that the excess entropy is a relic of the energetic winds generated by supernovae in the forming galaxies. These winds also enriched the intracluster medium with elements heavier than helium. We show that such a process can account for the observed effects only if the intracluster medium is heated at modest redshifts (z ≲ 2) but before the final collapse into a cluster structure, indicating that the formation of galaxies precedes that of clusters and that most clusters have been assembled very recently.

The Santa Barbara cluster comparison project: A comparison of cosmological hydrodynamics solutions

Abstract: We have simulated the formation of an X-ray cluster in a cold dark matter universe using 12 different codes. The codes span the range of numerical techniques and implementations currently in use, including smoothed particle hydrodynamics (SPH) and grid methods with fixed, deformable, or multilevel meshes. The goal of this comparison is to assess the reliability of cosmological gasdynamical simulations of clusters in the simplest astrophysically relevant case, that in which the gas is assumed to be nonradiative. We compare images of the cluster at different epochs, global properties such as mass, temperature and X-ray luminosity, and radial profiles of various dynamical and thermodynamical quantities. On the whole, the agreement among the various simulations is gratifying, although a number of discrepancies exist. Agreement is best for properties of the dark matter and worst for the total X-ray luminosity. Even in this case, simulations that adequately resolve the core radius of the gas distribution predict total X-ray luminosities that agree to within a factor of 2. Other quantities are reproduced to much higher accuracy. For example, the temperature and gas mass fraction within the virial radius agree to within about 10%, and the ratio of specific dark matter kinetic to gas thermal energies agree to within about 5%. Various factors, including differences in the internal timing of the simulations, contribute to the spread in calculated cluster properties. Based on the overall consistency of results, we discuss a number of general properties of the cluster we have modeled.

The Arctic and Antarctic oscillations and their projected changes under global warming

Abstract: The Arctic Oscillation (AO) and the Antarctic Oscillation (AAO) are the leading modes of high-latitude variability in each hemisphere as characterized by the first EOF of mean sea-level pressure. Observations suggest a recent positive trend in the AO and it is speculated that this may be related to global warming. The CCCma coupled general circulation model control simulation exhibits a robust and realistic AO and AAO. Climate change simulations for the period 1900–2100, with forcing due to greenhouse gases and aerosols, exhibit positive trends in both the AO and the AAO. The model simulates essentially unchanged AO/AAO variations superimposed on a forced climate change pattern. The results do not suggest that a simulated trend in the AO/AAO necessarily depends on stratospheric involvement nor that forced climate change will be expressed as a change in the occurence of one phase of the AO/AAO over another. This pattern of climate change projects exclusively on the AAO pattern in the southern hemisphere but not in the northern hemisphere where other EOFs are involved. The extent to which this forced climate change pattern and the unforced modes of variation are determined by the same mechanisms and feedbacks remains an open question.

Adult Attachment A Mediator Between Child Sexual Abuse and Later Psychological Adjustment

Abstract: This study investigated the nature of the relationship between child sexual abuse, adult attachment style as measured by the Relationship Questionnaire, and psychological adjustment as measured by the Trauma Symptom Inventory. Participants were 307 female university students, including 85 women with a history of child sexual abuse. Results indicated that a history of child sexual abuse predicted both psychological adjustment and adult attachment style, and that adult attachment style predicted psychological adjustment. In addition, a mediational model in which attachment mediates between child sexual abuse and later psychological adjustment was supported. Results are discussed in terms of implications for conducting therapy with child sexual abuse survivors.

Evidence for a system of general protein glycosylation in Campylobacter jejuni.

Abstract: A genetic locus from Campylobacter jejuni 81-176 (O:23, 36) has been characterized that appears to be involved in glycosylation of multiple proteins, including flagellin. The lipopolysaccharide (LPS) core of Escherichia coli DH5α containing some of these genes is modified such that it becomes immunoreactive with O:23 and O:36 antisera and loses reactivity with the lectin wheat germ agglutinin (WGA). Site-specific mutation of one of these genes in the E. coli host causes loss of O:23 and O:36 antibody reactivity and restores reactivity with WGA. However, site-specific mutation of each of the seven genes in 81-176 failed to show any detectable changes in LPS. Multiple proteins from various cellular fractions of each mutant showed altered reactivity by Western blot analyses using O:23 and O:36 antisera. The changes in protein antigenicity could be restored in one of the mutants by the presence of the corresponding wild-type allele in trans on a shuttle vector. Flagellin, which is known to be a glycoprotein, was one of the proteins that showed altered reactivity with O:23 and O:36 antiserum in the mutants. Chemical deglycosylation of protein fractions from the 81-176 wild type suggests that the other proteins with altered antigenicity in the mutants are also glycosylated.

Measuring the Hidden Economy: Implications for Econometric Modelling

Abstract: In this paper I support using econometric techniques to measure the size of the hidden (underground) economy, because such information is important for the construction of certain economic models, and for empirical policy analysis. Generally, detailed information on the output of the hidden economy is unavailable. Even where careful measures of the underground economy have been constructed, usually these data are available only periodically. Important exceptions are the classic results of Tanzi (1983) for the United States, and Bhattacharyya's (1990) series for the United Kingdom. In the case of the New Zealand economy, a time-series of data on the hidden economy has been generated recently (Giles, 1997a). This provides the unusual opportunity to undertake econometric modelling in a way which takes account of such activity formally. Moreover, we can examine the policy implications arising from the linkages between hidden output and various measured economic aggregates. (This abstract was borrowed from another version of this item.)

Toward an allocation scheme for global terrestrial carbon models

Abstract: Summary The distribution of assimilated carbon among the plant parts has a profound effect on plant growth, and at a larger scale, on terrestrial biogeochemistry. Although important progress has been made in modelling photosynthesis, less effort has been spent on understanding the carbon allocation, especially at large spatial scales. Whereas several individual-level models of plant growth include an allocation scheme, most global terrestrial models still assume constant allocation of net primary production (NPP) among plant parts, without any environmental coupling. Here, we use the CASA biosphere model as a platform for exploring a new global allocation scheme that estimates allocation of photosynthesis products among leaves, stems, and roots depending on resource availability. The philosophy underlying the model is that allocation patterns result from evolved responses that adjust carbon investments to facilitate capture of the most limiting resources, i.e. light, water, and mineral nitrogen. In addition, we allow allocation of NPP to vary in response to changes in atmospheric CO2. The relative magnitudes of changes in NPP and resource-use efficiency control the response of root:shoot allocation. For ambient CO2, the model produces realistic changes in above-ground allocation along productivity gradients. In comparison to the CASA standard estimate using fixed allocation ratios, the new allocation scheme tends to favour root allocation, leading to a 10% lower global biomass. Elevated CO2, which alters the balance between growth and available resources, generally leads to reduced water stress and consequently, decreased root:shoot ratio. The major exception is forest ecosystems, where increased nitrogen stress induces a larger root allocation.

The Cosmological Origin of the Tully-Fisher Relation

Abstract: We use high-resolution cosmological simulations that include the effects of gasdynamics and star formation to investigate the origin of the Tully-Fisher relation in the standard cold dark matter cosmogony. Stars are assumed to form in collapsing, Jeans-unstable gas clumps at a rate set by the local gas density and the dynamical/cooling timescale. The energetic feedback from stellar evolution is assumed to heat the gas-surrounding regions of ongoing star formation, where it is radiated away very rapidly. The star formation algorithm thus has little effect on the rate at which gas cools and collapses, and, as a result, most galaxies form their stars very early. Luminosities are computed for each model galaxy using their full star formation histories and the latest spectrophotometric models. We find that the stellar mass of model galaxies is proportional to the total baryonic mass within the virial radius of their surrounding halos. Circular velocity then correlates tightly with the total luminosity of the galaxy, which reflects the equivalence between mass and circular velocity of systems identified in a cosmological context. The slope of the relation steepens slightly from the blue to the red bandpasses and is in fairly good agreement with observations. Its scatter is small, decreasing from ~0.38 mag in the U band to ~0.24 mag in the K band. The particular cosmological model we explore here seems unable to account for the zero point of the correlation. Model galaxies are too faint at z=0 (by about 2 mag) if the circular velocity at the edge of the luminous galaxy is used as an estimator of the rotation speed. The model Tully-Fisher relation is brighter in the past by ~0.7 mag in the B band at z=1, which is at odds with recent observations of z~1 galaxies. We conclude that the slope and tightness of the Tully-Fisher relation can be naturally explained in hierarchical models, but that its normalization and evolution depend strongly on the star formation algorithm chosen and on the cosmological parameters that determine the universal baryon fraction and the time of assembly of galaxies of different mass.

Direct Measurement of the “Giant” Adiabatic Temperature Change in Gd 5 Si 2 Ge 2

Abstract: Direct adiabatic temperature change as well as magnetic measurements were carried out on two different samples of ${\mathrm{Gd}}_{5}{\mathrm{Si}}_{2}{\mathrm{Ge}}_{2}$ composition for which calculations predicted a ``giant'' magnetocaloric effect (MCE). While magnetic measurements well reproduce published values, serving the basis for the predictions, direct adiabatic temperature change measurements show a significantly smaller MCE. The discrepancy can be interpreted on the basis of the thermodynamics of first order magnetic transitions.

Measurement of the strong coupling constant αs and the vector and axial-vector spectral functions in hadronic tau decays the opal collaboration

Abstract: The spectral functions of the vector current and the axial-vector current have been measured in hadronic $\tau$ decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the strong coupling constant $\alpha_{\rm s}$ , the non-perturbative operators of dimension 6 and 8 and of the gluon condensate has been performed. Different perturbative descriptions have been compared to the data. The Contour Improved Fixed Order Perturbation Theory gives $\alpha_{\rm s}(m_\tau^2) = 0.348 \pm 0.009_{\rm exp} \pm 0.019_{\rm theo}$ at the $\tau$ -mass scale and $\alpha_{\rm s}(m^2_{\rm Z}) = 0.1219 \pm 0.0010_{\rm exp} \pm 0.0017_{\rm theo}$ at the ${\rm Z}^0$ -mass scale. The values obtained for $\alpha_{\rm s}(m^2_{\rm Z})$ using Fixed Order Perturbation Theory or Renormalon Chain Resummation are 2.3% and 4.1% smaller, respectively. The ‘running’ of the strong coupling between $s_0 \simeq 1.3 {\rm GeV}^2$ and $s_0 = m_\tau^2$ has been tested from direct fits to the integrated differential hadronic decay rate $R_\tau(s_0)$ . A test of the saturation of QCD sum rules at the $\tau$ -mass scale has been performed.

Randomized fully dynamic graph algorithms with polylogarithmic time per operation

Abstract: This paper solves a longstanding open problem in fully dynamic algorithms: We present the first fully dynamic algorithms that maintain connectivity, bipartiteness, and approximate minimum spanning trees in polylogarithmic time per edge insertion or deletion. The algorithms are designed using a new dynamic technique that combines a novel graph decomposition with randomization. They are Las-Vegas type randomized algorithms which use simple data structures and have a small constant factor.Let n denote the number of nodes in the graph. For a sequence of O(m0) operations, where m0 is the number of edges in the initial graph, the expected time for p updates is O(p log3n) (througout the paper the logarithms are based 2) for connectivity and bipartiteness. The worst-case time for one query is O(log n/log log n). For the k-edge witness problem (“Does the removal of k given edges disconnect the graph?”) the expected time for p updates is O(p log3n) and the expected time for q queries is O(qk log3n). Given a graph with k different weights, the minimum spanning tree can be maintained during a sequence of p updates in expected time O(pk log3n). This implies an algorithm to maintain a 1 + e-approximation of the minimum spanning tree in expected time O((p log3n logU)/e) for p updates, where the weights of the edges are between 1 and U.

The CNOC2 Field Galaxy Luminosity Function. I. A Description of Luminosity Function Evolution

Abstract: We examine the evolution of the galaxy luminosity function (LF) using a sample of over 2000 galaxies, with 0.12 < z < 0.55 and 17.0 < RC < 21.5, drawn from the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2), at present the largest such sample at intermediate redshifts. We use UBVRCIC photometry and the spectral energy distributions (SEDs) of Coleman, Wu, and Weedman to classify our galaxies into early, intermediate, and late types, for which we compute LFs in the rest-frame B, RC, and U bandpasses. In particular, we adopt a convenient parameterization of LF evolution including luminosity and number density evolution and take care to quantify correlations among our LF evolution parameters. We also carefully measure and account for sample selection effects as functions of galaxy magnitude and color. Our principal result is a clear quantitative separation of luminosity and density evolution for different galaxy populations and the finding that the character of the LF evolution is strongly dependent on galaxy type. Specifically, we find that the early- and intermediate-type LFs show primarily brightening at higher redshifts and only modest density evolution, whereas the late-type LF is best fit by strong number density increases at higher z with little luminosity evolution. We also confirm the trend seen in previous smaller z 1 samples of the contrast between the strongly increasing luminosity density of late-type galaxies and the relatively constant luminosity density of early-type objects. Specific comparisons against the Canada-France and Autofib redshift surveys show general agreement among our LF evolution results, although there remain some detailed discrepancies. In addition, we use our number count and color distribution data to further confirm the validity of our LF evolution models to z ~0.75, and we also show that our results are not significantly affected by potential systematic effects such as surface brightness selection, photometric errors, or redshift incompleteness.

Interaction of maturation delay and nonlinear birth in population and epidemic models.

Abstract: A population with birth rate function B(N) N and linear death rate for the adult stage is assumed to have a maturation delay T>0. Thus the growth equation N′(t)=B(N(t−T)) N(t−T) e− d 1 T−dN(t) governs the adult population, with the death rate in previous life stages d 1≧0. Standard assumptions are made on B(N) so that a unique equilibrium N e exists. When B(N) N is not monotone, the delay T can qualitatively change the dynamics. For some fixed values of the parameters with d 1>0, as T increases the equilibrium N e can switch from being stable to unstable (with numerically observed periodic solutions) and then back to stable. When disease that does not cause death is introduced into the population, a threshold parameter R 0 is identified. When R 0<1, the disease dies out; when R 0>1, the disease remains endemic, either tending to an equilibrium value or oscillating about this value. Numerical simulations indicate that oscillations can also be induced by disease related death in a model with maturation delay.

Hot Horizontal-Branch Stars: The Ubiquitous Nature of the ``Jump'' in Strömgren u, Low Gravities, and the Role of Radiative Levitation of Metals

Abstract: A "jump" in the BHB distribution in the V, u-y CMD was recently detected in the GC M13. It is morphologically best characterized as a discontinuity in u, u-y, with stars in the range 11,500 11,500 K, dramatically enhancing their abundances in the atmospheres of BHB stars in the "critical" temperature region. Model atmospheres taking diffusion effects into account are badly needed, and will likely lead to better overall agreement between canonical evolutionary theory and observations for BHB stars.

List Homomorphisms and Circular Arc Graphs

Abstract: , H, and lists \(\), a list homomorphism of G to Hwith respect to the listsL is a mapping \(\), such that \(\) for all \(\), and \(\) for all \(\). The list homomorphism problem for a fixed graph H asks whether or not an input graph G together with lists \(\), \(\), admits a list homomorphism with respect to L. We have introduced the list homomorphism problem in an earlier paper, and proved there that for reflexive graphs H (that is, for graphs H in which every vertex has a loop), the problem is polynomial time solvable if H is an interval graph, and is NP-complete otherwise. Here we consider graphs H without loops, and find that the problem is closely related to circular arc graphs. We show that the list homomorphism problem is polynomial time solvable if the complement of H is a circular arc graph of clique covering number two, and is NP-complete otherwise. For the purposes of the proof we give a new characterization of circular arc graphs of clique covering number two, by the absence of a structure analogous to Gallai's asteroids. Both results point to a surprising similarity between interval graphs and the complements of circular arc graphs of clique covering number two.

Using a Broadband ADCP in a Tidal Channel. Part II: Turbulence

Abstract: A four-transducer, 600-kHz, broadband acoustic Dopple current profiler (ADCP) was rigidly mounted to the bottom of a fully turbulent tidal channel with peak flows of 1 m s−1. Rapid samples of velocity data are used to estimate various parameters of turbulence with the covariance technique. The questions of bias and error sources, statistical uncertainty, and spectra are addressed. Estimates of the Reynolds stress are biased by the misalignment of the instrument axis with respect to vertical. This bias can be eliminated by a fifth transducer directed along the instrument axis. The estimates of turbulent kinetic energy (TKE) density have a systematic bias of 5 × 10−4 m2 s−2 due to Doppler noise, and the relative statistical uncertainty of the 20-min averages is usually less than 20%–95% confidence. The bias in the Reynolds stress due to Doppler noise is less than ±4 × 10−5 m2. The band of zero significance is never less than 1.5 × 10−5 m2 s−2 due to Doppler noise, and this band increases with incre...

The effects of nitrogen stress on the stable carbon isotope composition, productivity and water use efficiency of white spruce (Picea glauca (Moench) Voss) seedlings

Abstract: The effect of nitrogen stress on needle δ 13 C, water-use efficiency (WUE) and biomass production in irrigated and dry land white spruce (Picea glauca (Moench) Voss) seedlings was investigated. Sixteen hundred seedlings, representing 10 controlled crosses, were planted in the field in individual buried sand-filled cylinders. Two nitrogen treatments were imposed, nitrogen stressed and fertilized. The ranking of δ 13 C of the crosses was maintained across all combinations of water and nitrogen treatments and there was not a significant genetic versus environmental interaction. The positive relationships between needle δ 13 C, WUE and dry matter production demonstrate that it should be possible to use δ 13 C as a surrogate for WUE, and to select for increased WUE without compromising yield, even in nitrogen deficient environments. Nitrogen stressed seedlings had the lowest needle δ 13 C in both irrigated and dry land conditions. There was a positive correlation between needle nitrogen content and δ 13 C that was likely associated with increased photosynthetic capacity. There was some indication that decreased nitrogen supply led to increased stomatal conductance and hence lower WUE. There was a negative correlation between intrinsic water use efficiency and photosynthetic nitrogen use efficiency (NUE). This suggests that white spruce seedlings have the ability to maximize NUE when water becomes limited. There was significant genetic variation in NUE that was maintained across treatments. Our results suggest that in white spruce, there is no detectable effect of anaplerotic carbon fixation and that it is more appropriate to use a value of 29‰ ('Rubisco only') for the net discrimination against 13 C during CO 2 fixation. This leads to excellent correspondence between values of C l /C a derived from gas exchange measurements or from δ 13 C.

Human DNA repair systems: an overview.

Abstract: DNA repair systems act to maintain genome integrity in the face of replication errors, environmental insults, and the cumulative effects of age. More than 70 human genes directly involved in the five major pathways of DNA repair have been described, including chromosomal location and cDNA sequence. However, a great deal of information as to the precise functions of these genes and their role in human health is still lacking. Hence, we summarize what is known about these genes and their contra part in bacterial, yeast, and rodent systems and discuss their involvement in human disease. While some associations are already well understood, it is clear that additional diseases will be found which are linked to DNA repair defects or deficiencies.

Determinants of DNA Sequence Specificity of the Androgen, Progesterone, and Glucocorticoid Receptors: Evidence for Differential Steroid Receptor Response Elements

Abstract: While androgen, progesterone, and glucocorticoid receptors perform distinct physiological functions by regulating unique sets of genes, in vitro they can transactivate a common high-affinity DNA-binding target. Naturally occurring steroid response elements display nucleotide divergence that lowers binding affinity in comparison to the optimal binding element, but enhances receptor-type specificity. We investigated the role of nucleotide deviations within the DNA-binding site for contribution to steroid receptor specificity. We hypothesized that receptor specificity drives the evolution of binding site sequence, rather than strictly receptor-binding affinity. Receptor-selective targets can evolve by some nucleotides selected on the basis of additional bond energy, and others may be selected by differential tolerance to discourage binding from inappropriate receptors. To identify receptor-specific binding sites, we mimicked these dual selection pressures in a receptor-competitive environment in which DNA binding sites for the androgen or progesterone receptors were selected in the presence of the glucocorticoid receptor. These analyses also demonstrated that steroid receptors strongly select nucleotides in the spacer and flanking regions of the half-site and do so in an asymmetric fashion, indicating that steroid receptors interact with DNA in an allosteric manner that affects the transcriptional activation potential. (Molecular Endocrinology 13: 2090‐2107, 1999)

The agonic freedom of citizens

Abstract: The ways citizen participation and democracy are changing are poorly understood due to the dominance of theories inherited from the eioghteenth centruy: Democratic citizenship can be better understood if critical reflection is re-oriented around the games of concrete freedom here and now as recommended by Hannah Arendt, Ludwing Wittgenstein, Michel Foucault and Quentin Skinner. This orientation brings to light two distrinctive types of citizen freedom in the present: diverse forms of citizen participation and diverse practices of governance in which citizens participate.