Matching the Local and Cosmic Star Formation Histories

Given the many recent advances in our understanding of the star formation history (SFH) of the Local Group and other nearby galaxies, and in the evolution of star formation with redshift, we present a new comparison of the comoving space density of the star formation rate as a function of look-back time for the Local and Distant Universe. We update the Local SFH derived from the analysis of resolved stellar populations (``fossil records'') in individual nearby galaxies, based on our own estimations as well as available in the literature. While the preliminary comparison of SFHs is found to be broadly consistent, some discrepancies still remain, including an excess of the Local SFR density in the most recent epoch.Comment: 4 pages, slightly revised version from a contribution to 'Galaxies in the Local Volume', Sydney, 8 - 13 July 2007, B. Koribalski and H. Jerjen, ed

Gauge Theory Correlators from Non-Critical String Theory

We suggest a means of obtaining certain Green's functions in 3+1-dimensional ${\cal N} = 4$ supersymmetric Yang-Mills theory with a large number of colors via non-critical string theory. The non-critical string theory is related to critical string theory in anti-deSitter background. We introduce a boundary of the anti-deSitter space analogous to a cut-off on the Liouville coordinate of the two-dimensional string theory. Correlation functions of operators in the gauge theory are related to the dependence of the supergravity action on the boundary conditions. From the quadratic terms in supergravity we read off the anomalous dimensions. For operators that couple to massless string states it has been established through absorption calculations that the anomalous dimensions vanish, and we rederive this result. The operators that couple to massive string states at level $n$ acquire anomalous dimensions that grow as 2\left (n g_{YM} \sqrt {2 N} )^{1/2} for large `t Hooft coupling. This is a new prediction about the strong coupling behavior of large $N$ SYM theory.Comment: 15 pages, harvmac with btxmac; minor revisions, 1 reference added, the version to appear in Physics Letters

On causality, unitarity and perturbative expansions

We present a pedagogical case study how to combine micro-causality and unitarity based on a perturbative approach. The method we advocate constructs an analytic extrapolation of partial-wave scattering amplitudes that is constrained by the unitarity condition. Suitably constructed conformal mappings help to arrive at a systematic approximation of the scattering amplitude. The technique is illustrated at hand of a Yukawa interaction. The typical case of a superposition of strong short-range and weak long-range forces is investigated.Comment: 12 pages, 12 figure

ISO 9000 Series Certification Over Time: what have we learnt?

The ISO 9000 experiences of the same sample of organisations over a five year time period is examined in this paper. The responses to a questionnaire sent out at the end of 1999 to companies which had a reasonably long term experience with the ISO 9000 series quality system are analysed. These companies were ISO 9000 series certified before 1994 when the authors conducted their first survey on the same sample. The main aim is to explore the links between the motivation for undertaking the ISO 9000 series and continued certification, with the impact on the type of TQM practices that have been adopted after certification, and what kind of gains have been achieved. Challenges faced by these organisations over time are also addressed

From Glossaries to Ontologies: Disaster Management Domain

Our society’s reliance on a variety of critical infrastructures (CI) presents significant challenges for disaster preparedness, response and recovery. Experts from different domains including police, paramedics, firefighters and various other CI teams are involved in the fast paced response to a disaster, increasing the risk of miscommunication. To ensure clear communication, as well as to facilitate CI software interoperability, a common disaster ontology is needed. We propose using the knowledge stored in domain glossaries, vocabularies and dictionaries for the creation of a lightweight disaster management domain ontology. Glossaries, vocabularies and dictionaries are semi structured representations of domain knowledge, where significant human effort has been invested in choosing relevant terms, determining their definitions, acronyms, synonyms and sometimes even relations. We use that knowledge built into semi formatted documents for ontology learning. In particular, we look at five glossaries/vocabularies from the disaster management domain and analyze their content similarity and structure. A lightweight disaster ontology is created exploiting the structure of the semi-structured source documents

Asymptotic normalization coefficients for 8B->7Be+p from a study of 8Li->7Li+n

Asymptotic normalization coefficients (ANCs) for 8Li->7Li+n have been extracted from the neutron transfer reaction 13C(7Li,8Li)12C at 63 MeV. These are related to the ANCs in 8B->7Be+p using charge symmetry. We extract ANCs for 8B that are in very good agreement with those inferred from proton transfer and breakup experiments. We have also separated the contributions from the p_1/2 and p_3/2 components in the transfer. We find the astrophysical factor for the 7Be(p,gamma)8B reaction to be S_17(0)=17.6+/-1.7 eVb. This is the first time that the rate of a direct capture reaction of astrophysical interest has been determined through a measurement of the ANCs in the mirror system.Comment: 5 pages, 3 figures, 2 table

Aligning archive maps and extracting footprints for analysis of historic urban environments.

Archive cartography and archaeologist's sketches are invaluable resources when analysing a historic town or city. A virtual reconstruction of a city provides the user with the ability to navigate and explore an environment which no longer exists to obtain better insight into its design and purpose. However, the process of reconstructing the city from maps depicting features such as building footprints and roads can be labour intensive. In this paper we present techniques to aid in the semi-automatic extraction of building footprints from digital images of archive maps and sketches. Archive maps often exhibit problems in the form of inaccuracies and inconsistencies in scale which can lead to incorrect reconstructions. By aligning archive maps to accurate modern vector data one may reduce these problems. Furthermore, the efficiency of the footprint extraction methods may be improved by aligning either modern vector data or previously extracted footprints, since common elements can be identified between maps of differing time periods and only the difference between the two needs to be extracted. An evaluation of two alignment approaches is presented: using a linear affine transformation and a set of piecewise linear affine transformations

Entropic N-bound and Maximal Mass Conjecture Violations in Four Dimensional Taub-Bolt(NUT)-dS Spacetimes

We show that the class of four-dimensional Taub-Bolt(NUT) spacetimes with positive cosmological constant for some values of NUT charges are stable and have entropies that are greater than that of de Sitter spacetime, in violation of the entropic N-bound conjecture. We also show that the maximal mass conjecture, which states "any asymptotically dS spacetime with mass greater than dS has a cosmological singularity", can be violated as well. Our calculation of conserved mass and entropy is based on an extension of the path integral formulation to asymptotically de Sitter spacetimes.Comment: 37 pages, 22 figures, 3 tables, few typos corrected, version to appear in Nucl. Phys.

Trifling matters: differential regulation of feedforward and feedback interneurons of the dentate gyrus by release of endogenous norepinephrine

Norepinephrine is known to play an important role in hippocampal function. Norepinephrine is required for long-term potentiation in dentate gyrus, and norepinephrine blockade or depletion can interfere with acquisition and retrieval in hippocampal dependent tasks. While gross measures of hippocampal function such as evoked potentials demonstrate plastic changes under the influence of norepinephrine, single unit studies to date report suppression of principle cell firing and increased firing rates for inhibitory interneurons. Such changes should reflect an increase in inhibition and would predict a decrease in plasticity. -- In this thesis I examine the effect of "natural" synaptic release of norepinephrine on spontaneous firing rates of cells in dentate gyrus, with concomitant electroencephalographic recording. Physiologically identified interneurons are classified as either feedforward or feedback depending on whether they were activated prior to, or after, the perforant path evoked population spike. Principle cells are identified by their characteristic firing properties and a firing latency within the window of the performant path evoked population spike. -- In this study feedforward interneurons virtually cease firing in response to synaptic release of norepinephrine, producing a period of disinhibition which lasts several minutes. Simultaneously, cells identified as principle cells increase their firing rates. Feedback interneurons demonstrated a mixed profile with some cells increasing their firing rates and others decreasing their firing rates. -- Fast Fourier analysis of the electroencephalographic recordings revealed a increase in relative power in the theta band as reported previously, together with a decrease in overall power and a decrease in relative power of the gamma band. These data are compared to previous studies of noradrenergic effects on single unit, evoked potential, and electroencephalography measures in the literature. The results are also compared to existing models of plasticity such as long-term potentiation and gamma power regulated acquisition and recall of hippocampal representations. Finally a new framework is proposed as to how norepinephrine may play a role in plasticity by allowing new information to be bound to mature hippocampal representations