Henon-like maps with arbitrary stationary combinatorics

We extend the renormalisation operator introduced in \cite{dCML} from period-doubling H\'enon-like maps to H\'enon-like maps with arbitrary stationary combinatorics. We show the renormalisation picture holds also holds in this case if the maps are taken to be \emph{strongly dissipative}. We study infinitely renormalisable maps $F$ and show they have an invariant Cantor set $\mathcal{O}$ on which $F$ acts like a $p$-adic adding machine for some $p>1$. We then show, as for the period-doubling case in \cite{dCML}, the sequence of renormalisations have a universal form, but the invariant Cantor set $\mathcal{O}$ is non-rigid. We also show $\mathcal{O}$ cannot possess a continuous invariant line field.Comment: 62 pages, 5 figure

A collimated flow driven by radiative pressure from the nucleus of quasar Q~1511+091

High velocity outflows from quasars are revealed by the absorption signatures they produce in the spectrum of the quasar. Clues on the nature and origin of these flows are important for our understanding of the dynamics of gas in the central regions of the Active Galactic Nucleus (AGNs) but also of the metal enrichment of the intergalactic space. Line radiation pressure has often been suggested to be an important process in driving these outflows, however no convincing evidence has been given so far. Here we report observation of a highly structured flow, toward Q~1511+091, where the velocity separations between distinct components are similar to O VI, N V and C IV doublet splittings with some of the profiles matching perfectly. This strongly favors the idea that the absorbing clumps originate at similar physical location and are driven by radiative acceleration due to resonance lines. The complex absorption can be understood if the flow is highly collimated so that the different optically thick clouds are aligned and cover the same region of the background source. One component shows saturated H I Lyman series lines together with absorptions from excited levels from C II and Si II but covers only 40% of the source of continuum. The fact that clouds cover only part of the small continuum source implies that the flow is located very close to it.Comment: 6 pages, 5 figures to appear in MNRA

Paying Attention to the Signs

Legal ethics is considered the step-child of legal education, and serious scholarship in legal ethics is considered somewhat of an oxymoron. Koniak and Hazard set out to produce materials that would help law students learn something about their responsibilities as lawyers and that would encourage a serious approach toward those responsibilities and the complexity of being an ethical person in an unredeemed and often unforgiving world

Improving starch and fibre in wheat grain for human health

Reducing the prevalence of diet- related diseases, including obesity and type 2 diabetes, is a major challenge for health professionals, food manufacturers and governments in both developed and developing countries. Cereals are key targets in meeting this challenge as they are staple foods throughout the world and major sources of energy (derived principally from starch) and dietary fibre. Wheat is the staple cereal in the UK and Europe, and the UK Biotechnology and Biological Sciences Research Council (BBSRC)- supported Designing Future Wheat programme is focused on manipulating the content and composition of starch and fibre to improve health impacts, including reducing the glycaemic response and improving fermentation in the colon. This work is contributing to the development of improved cultivars by breeders and foods by processors. It is also increasing our understanding of the behaviour of these components in the human gastrointestinal (GI) tract and will contribute to the establishment of targets and recommendations for regulatory authorities

Contrasting arbuscular mycorrhizal communities colonizing different host plants show a similar response to a soil phosphorus concentration gradient

High soil phosphorus (P) concentration is frequently shown to reduce root colonization by arbuscular mycorrhizal (AM) fungi, but the influence of P on the diversity of colonizing AM fungi is uncertain. We used terminal restriction fragment length polymorphism (T-RFLP) of 18S rDNA and cloning to assess diversity of AM fungi colonizing maize (Zea mays), soybean (Glycene max) and field violet (Viola arvensis) at three time points in one season along a P gradient of 10–280 mg l−1 in the field. Percentage AM colonization changed between sampling time points but was not reduced by high soil P except in maize. There was no significant difference in AM diversity between sampling time points. Diversity was reduced at concentrations of P > 25 mg l−1, particularly in maize and soybean. Both cloning and T-RFLP indicated differences between AM communities in the different host species. Host species was more important than soil P in determining the AM community, except at the highest P concentration. Our results show that the impact of soil P on the diversity of AM fungi colonizing plants was broadly similar, despite the fact that different plants contained different communities. However, subtle differences in the response of the AM community in each host were evident

The Metallicity of High Redshift Galaxies: The Abundance of Zinc in 34 Damped Lyman Alpha Systems from z = 0.7 to 3.4

We report new observations of ZnII and CrII absorption lines in 10 damped \lya systems (DLAs), mostly at redshift z_{abs} \simgt 2.5 . By combining these results with those from our earlier survey (Pettini et al. 1994) and other recent data, we construct a sample of 34 measurements (or upper limits) of the Zn abundance relative to hydrogen [Zn/H]; the sample includes more than one third of the total number of DLAs known. The plot of the abundance of Zn as a function of redshift reinforces the two main findings of our previous study. (1) Damped \lya systems are mostly metal-poor, at all redshifts sampled; the column density weighted mean for the whole data set is [Zn/H] $= -1.13 \pm 0.38$ (on a logarithmic scale), or approximately 1/13 of solar. (2) There is a large spread, by up to two orders of magnitude, in the metallicities we measure at essentially the same redshifts. We propose that damped \lya systems are drawn from a varied population of galaxies of different morphological types and at different stages of chemical evolution, supporting the idea of a protracted epoch of galaxy formation. At redshifts z \simgt 2 the typical metallicity of the damped \lya systems is in agreement with expectations based on the consumption of HI gas implied by the recent measurements of $\Omega_{DLA}$ by Storrie-Lombardi et al. (1996a), and with the metal ejection rates in the universe at these epochs deduced by Madau (1996) from the ultraviolet luminosities of high redshift galaxies revealed by deep imaging surveys. There are indications in our data for an increase in the mean metallicity of the damped \lya systems from $z > 3$ to $\approx 2$, consistent with the rise in the comoving star formation rate indicated by the relative numbers of $U$ and $B$ drop-outs in the Hubble Deep Field. Although such comparisons are still tentative, it appears that these different avenues for exploring the early evolution of galaxies give a broadly consistent picture.Comment: 51 pages, LaTeX, 9 Postscript Figures. Accepted for publication in the Astrophysical Journa

An Infrared Search for Star-Forming Galaxies at z > 2

We report the cumulative results of an on-going near-infrared search for redshifted H-alpha emission from normal galaxies at z>2. An infrared search reduces the bias due to reddening. Using narrow-band imaging with the Near Infrared Camera on the Keck I 10-m telescope, a survey area of almost 12 square arcminutes has been covered. Target regions were selected by matching the redshifts of QSO emission and metal-line absorptions to our available filters. The survey depth is 7E-17 ergs/cm^2/s (3sigma) in H-alpha and K-prime ~22. Eleven H-alpha-emitters, plus two Seyfert I objects, have been discovered. The high density of galaxy detections, corresponding to a co-moving volume density of 0.0135/Mpc^3, makes it unlikely that all of the H-alpha flux in these objects is the result of active nuclei. There is a strong suggestion of clustering in the environments of metal-line absorbers. Each candidate galaxy lies typically within a projected distance of 250kpc of the QSO line of sight and is resolved but compact. The average Star Formation Rate inferred for the galaxies from the H-alpha flux is 50 Msun/yr, significantly higher than current day star-forming galaxies, but consistent with other estimates for galaxies at high redshift.Comment: 39 pages including 17 figures, accepted for publication in Ap

No elliptic islands for the universal area-preserving map

A renormalization approach has been used in \cite{EKW1} and \cite{EKW2} to prove the existence of a \textit{universal area-preserving map}, a map with hyperbolic orbits of all binary periods. The existence of a horseshoe, with positive Hausdorff dimension, in its domain was demonstrated in \cite{GJ1}. In this paper the coexistence problem is studied, and a computer-aided proof is given that no elliptic islands with period less than 20 exist in the domain. It is also shown that less than 1.5% of the measure of the domain consists of elliptic islands. This is proven by showing that the measure of initial conditions that escape to infinity is at least 98.5% of the measure of the domain, and we conjecture that the escaping set has full measure. This is highly unexpected, since generically it is believed that for conservative systems hyperbolicity and ellipticity coexist