8,342 research outputs found
Advice to Students Considering Graduate Work in English
Drawing on specific case histories from over 50 students who applied to graduate programs in English Literature, Composition, and Writing, this document represents my advice to students applying nationwide to do graduate work in the various subfields of English studies
The covariant scattering and cohomology of strings
A general formalism for covariant string scattering is given. It is
found necessary to use screening charges that are constructed from the
fields including ghosts. The scattering amplitudes so constructed contain
within them Ising model correlation functions and agree with those found
previously by the authors. Using the screening charge and a picture changing
operator, an infinite number of states in the cohomology of Q are generated
from only three states. We conjecture that, apart from discrete states, these
are all the states in the cohomology of Q.Comment: 36 pages, KCL-TH-93-
The spectroscopic detection of drugs of abuse in fingerprints after development with powders and recovery with adhesive lifters
The application of powders to fingerprints has long been established as an effective and reliable method
for developing latent fingerprints. Fingerprints developed in situ at a crime scene routinely undergo lifting
with specialist tapes and are then stored in evidence bags to allow secure transit and also to preserve the
chain of evidence. In a previous study we have shown that exogenous material within a fingerprint can
be detected using Raman spectroscopy following development with powders and lifting with adhesive
tapes. Other reports have detailed the use of Raman spectroscopy to the detection of drugs of abuse
in latent fingerprints including cyanoacrylate-fumed fingerprints. This study involves the application of
Raman spectroscopy for the analysis of drugs of abuse in latent fingerprints for fingerprints that had
been treated with powders and also subsequently lifted with adhesive tapes. Samples of seized ecstasy,
cocaine, ketamine and amphetamine were supplied by East Sussex Police and by the TICTAC unit at St.
Georges Hospital Tooting. Contaminated fingerprintswere deposited on clean glass slides. The application
of aluminium or iron based powders to contaminated fingerprints did not interfere with theRamanspectra
obtained for the contaminants. Contaminated fingerprints developed with powders and then lifted with
lifting tapes were also examined. The combination of these two techniques did not interfere with the
successful analysis. The lifting processwas repeated using hinge lifters. As the hinge lifters exhibited strong
Raman bands the spectroscopic analysiswas more complex and an increase in the number of exposures to
the detector allowed for improved clarification. Spectral subtraction was performed to remove peaks due
to the hinge lifters using OMNIC software. Raman spectra of developed and lifted fingerprints recorded
through evidence bags were obtained and it was found that the detection process was not compromised.
Although the application of powders did not interfere with the detection process the time taken to locate
the contaminant was increased due to the physical presence of more material within the fingerprint
Journalists\u27 Views of the Environment: Issues and Challenges
In advocating the use of an environmental handbook for journalists, the authors report on a survey of reporters and editors regarding salient environmental issues in different regions of the United States and e emphasis placed on environmental reporting in newsrooms
Substructure: Clues to the Formation of Clusters of Galaxies
We have examined the spatial distribution of substructure in clusters of
galaxies using Einstein X-ray observations. Subclusters are found to have a
markedly anisotropic distribution that reflects the surrounding matter
distribution on supercluster scales. Our results suggest a picture in which
cluster formation proceeds by mergers of subclusters along large-scale
filaments. The implications of such an anisotropic formation process for the
shapes, orientations and kinematics of clusters are discussed briefly.Comment: 7 pages, uuencoded compressed postscript. To appear in ApJ Letters
(September 20, 1995 issue
The Formation of Giant Elliptical Galaxies and Their Globular Cluster Systems
The bimodal globular cluster (GC) metallicity distributions of many giant
elliptical galaxies are often cited as evidence for the formation of such
galaxies through mergers involving gas-rich spirals. In such models, the metal-
rich GCs are assumed to have formed during the merger process. We explore an
alternative possibility: that these metal-rich clusters represent the galaxy's
intrinsic GC population and that the metal-poor component of the observed GC
metallicity distribution arises from the capture of GCs from other galaxies,
either through mergers or through tidal stripping. Starting with plausible
assumptions for the initial galaxy luminosity function and for the dependence
of GC metallicity on parent galaxy luminosity, we show that the growth of a
pre-existing seed galaxy through mergers and tidal stripping is accompanied by
the capture of metal-poor GCs whose properties are similar to those which are
observed to surround giant ellipticals. We describe a method of using the
observed number of metal-poor and metal-rich GCs to infer the merger histories
of individual elliptical galaxies, and use this technique to derive limits on
the number of galaxies and total luminosity accreted to date by M49. We argue
that although GC specific frequency is conserved in galaxy mergers, the same
may not be true of tidal stripping by the mean field of the host galaxy
cluster. Comparisons of model GC metallicity distributions and specific
frequencies to those observed for the well-studied galaxies M49 and M87 show
that it is possible to explain their bimodal GC metallicity distributions and
discordant specific frequencies without resorting to the formation of new GCs
in mergers or by invoking multiple bursts of GC formation.Comment: 39 pages AAS Latex and 10 postscript figures. Also available at
http://astro.caltech.edu/~pc. Accepted for publication in the Astrophysical
Journa
Non-thermal X-ray Emission: An Alternative to Cluster Cooling Flows?
We report the results of experiments aimed at reducing the major problem with
cooling flow models of rich cluster X-ray sources: the fact that most of the
cooled gas or its products have not been found. Here we show that much of the
X-ray emission usually attributed to cooling flows can, in fact, be modeled by
a power-law component which is indicative of a source(s) other than thermal
bremsstrahlung from the intracluster medium. We find that adequate simultaneous
fits to ROSAT PSPCB and ASCA GIS/SIS spectra of the central regions of ten
clusters are obtained for two-component models that include a thermal plasma
component that is attributable to hot intracluster gas and a power-law
component that is likely generated by compact sources and/or extended
non-thermal emission. For five of the clusters that purportedly have massive
cooling flows, the best-fit models have power-law components that contribute
30 % of the total flux (0.14 - 10.0 keV) within the central 3
arcminutes. Because cooling flow mass deposition rates are inferred from X-ray
fluxes, our finding opens the possibility of significantly reducing cooling
rates.Comment: 11 pages, 3 figures, emulateapj style. Accepted for publication in
Ap
- …