1,599 research outputs found
Recommended from our members
Notations and conventions in molecular spectroscopy: part 1. General spectroscopic notation
The field of Molecular Spectroscopy was surveyed in order to determine a set of
conventions and symbols which are in common use in the spectroscopic literature. This
document, which is Part I in a series, establishes the notations and conventions used for
general spectroscopic notations and deals with quantum mechanics, quantum numbers
(vibrational states, angular momentum and energy levels), spectroscopic transitions, and
miscellaneous notations (e.g. spectroscopic terms). Further parts will follow, dealing inter
alia with symmetry notation, permutation and permutation-inversion symmetry notation,
vibration-rotation spectroscopy and electronic spectroscopy
Recommended from our members
Notations and conventions in molecular spectroscopy: part 2. Symmetry notation
The field of Molecular Spectroscopy was surveyed in order to determine a set of
conventions and symbols which are in common use in the spectroscopic literature. This
document, which is Part 2 in a series, establishes the notations and conventions used for the
description of symmetry in rigid molecules, using the Schoenflies notation. It deals firstly
with the symmetry operators of the molecular point groups (also drawing attention to the
difference between symmetry operators and elements). The conventions and notations of the
molecular point groups are then established, followed by those of the representations of these
groups as used in molecular spectroscopy. Further parts will follow, dealing inter alia with
permutation and permutation-inversion symmetry notation, vibration-rotation spectroscopy
and electronic spectroscopy
The role of quenching time in the evolution of the mass-size relation of passive galaxies from the WISP survey
We analyze how passive galaxies at z 1.5 populate the mass-size plane
as a function of their stellar age, to understand if the observed size growth
with time can be explained with the appearance of larger quenched galaxies at
lower redshift. We use a sample of 32 passive galaxies extracted from the Wide
Field Camera 3 Infrared Spectroscopic Parallel (WISP) survey with spectroscopic
redshift 1.3 z 2.05, specific star-formation rates lower
than 0.01 Gyr, and stellar masses above 4.5 10
M. All galaxies have spectrally determined stellar ages from fitting of
their rest-frame optical spectra and photometry with stellar population models.
When dividing our sample into young (age 2.1 Gyr) and old (age 2.1
Gyr) galaxies we do not find a significant trend in the distributions of the
difference between the observed radius and the one predicted by the mass-size
relation. This result indicates that the relation between the galaxy age and
its distance from the mass-size relation, if it exists, is rather shallow, with
a slope alpha -0.6. At face value, this finding suggests that
multiple dry and/or wet minor mergers, rather than the appearance of newly
quenched galaxies, are mainly responsible for the observed time evolution of
the mass-size relation in passive galaxies.Comment: Accepted for publication in ApJ Letters; 6 pages, 3 figures, 1 tabl
Measurements of ice nucleation by mineral dusts in the contact mode
Formation of ice in Earth\u27s atmosphere at temperatures above approximately −20 °C is one of the outstanding problems in cloud physics. Contact nucleation has been suggested as a possible mechanism for freezing at relatively high temperatures; some laboratory experiments have shown contact freezing activity at temperatures as high as −4 °C. We have investigated Arizona Test Dust and kaolinite as contact nuclei as a function of size and temperature and find that the fraction of submicron particles that are active as contact ice nuclei is less than 10−3 for −18 °C and greater. We also find that the different dusts are quite distinct in their effectiveness as contact nuclei; Arizona Test Dust catalyzed freezing in the contact mode at all mobility diameters we tested at −18 °C whereas kaolinite triggered freezing only for mobility diameters of 1000 and 500 nm at that temperature
Evaluating Banking Websites Privacy Statements – A New Zealand Perspective on Ensuring Business Confidence
Because banks deal with highly personal detailed and sensitive information, they need to establish and maintain the confidence of their customers more assiduously than most other businesses. The rise of internet banking and the advantages to be gained from the garnering of personal data from websites places banks in a position to exploit customer data in a way that might infringe ethical considerations. This investigation analyses the website privacy statements of New Zealand banks in terms of the provisions of the New Zealand Privacy Act. The intention was to find an objective basis for the assessment of business integrity, to explore how confidence in electronic commerce can be assured. The investigation finds that the use of privacy legislation principles as a means of evaluating website privacy statements is revealing and convincing. It is considered that customer confidence will increasingly impact on Internet businesses, and business integrity as demonstrated by comprehensive and relevant privacy statements will go a long way to provide those assurances
Recommended from our members
Effect of colloidal aggregation on the sedimentation and rheological properties of tank waste
Tank farm experience and work performed under the Tank Waste Treatment Science task of the Tank Waste Remediation System (TWRS) Pretreatment Technology Development Project indicate that colloidal interactions can have an enormous impact on tank waste processing. This report provides the theoretical and experimental background required to understand how such agglomeration phenomena control the sedimentation and theological behavior of colloidal tank wastes. First, the report describes the conditions under which the colloidal particles present in tank sludge are expected to aggregate. Computational models have been developed to predict solution conditions leading to agglomeration, and to predict the rate and size of aggregate growth. The models show that tank sludge should be heavily agglomerated under most baseline processing conditions. Second, the report describes models used to predict sedimentation rates and equilibrium sediment density profiles based on knowledge of agglomerate structures. The sedimentation models provide a self-consistent picture that explains the apparent discrepancies between bench-top experiments and tank-farm experience. Finally, both discrete and empirical models are presented that can be used to rationalize and predict the rheological properties of colloidal sludge suspensions. In all cases, model predictions are compared and contrasted with experimental results. The net results indicate that most of the observed behaviors of real sludges can be predicted, understood, and perhaps ultimately controlled by understanding a few key central concepts regarding agglomeration phenomena
Red Companions to a z=2.15 Radio Loud Quasar
We have conducted observations of the environment around the z=2.15 radio
loud quasar 1550-269 in search of distant galaxies associated either with it or
the z=2.09 CIV absorber along its line of sight. Such objects will be
distinguished by their red colours, R-K>4.5. We find five such objects in a 1.5
arcmin^2 field around the quasar, with typical K magnitudes of ~20.4 and no
detected R band emission. We also find a sixth object with K=19.6+/-0.3, and
undetected at R, just two arcseconds from the quasar. The nature of all these
objects is currently unclear, and will remain so until we have determined their
redshifts. We suggest that it is likely that they are associated with either
the quasar or the CIV absorber, in which case their properties might be similar
to those of the z=2.38 red Ly-alpha emitting galaxies discovered by Francis et
al. (1997). The small separation between the quasar and the brightest of our
objects suggests that it may be the galaxy responsible for the CIV metal line
absorption system. The closeness to the quasar and the red colour might have
precluded similar objects from being uncovered in previous searches for
emission from CIV and eg. damped absorbers.Comment: To appear in "Photometric Redshifts and High Redshift Galaxies", eds.
R. Weymann, L. Storrie-Lombardi, M. Sawicki & R. Brunne
An Optical/Near-Infrared Study of Radio-Loud Quasar Environments II. Imaging Results
We use optical and near-IR imaging to examine the properties of the
significant excess population of K>=19 galaxies found in the fields of 31 z=1-2
radio-loud quasars by Hall, Green & Cohen (1998). The excess occurs on two
spatial scales: a component at <40'' from the quasars significant compared to
the galaxy surface density at >40'' in the same fields, and a component roughly
uniform to ~100'' significant compared to the galaxy surface density seen in
random-field surveys in the literature. The r-K color distributions of the
excess galaxy populations are indistinguishable and are significantly redder
than the color distribution of the field population.
The excess galaxies are consistent with being predominantly early-type
galaxies at the quasar redshifts, and there is no evidence that they are
associated with intervening MgII absorption systems. The average excess within
0.5 Mpc (~65'') of the quasars corresponds to Abell richness class ~0 compared
to the galaxy surface density at >0.5 Mpc from the quasars, and to Abell
richness class ~1.5 compared to that from the literature.
We discuss the spectral energy distributions (SEDs) of galaxies in fields
with data in several passbands. Most candidate quasar-associated galaxies are
consistent with being 2-3 Gyr old early-types at the quasar redshifts of z~1.5.
However, some objects have SEDs consistent with being 4-5 Gyr old at z~1.5, and
a number of others are consistent with ~2 Gyr old but dust-reddened galaxies at
the quasar redshifts. These potentially different galaxy types suggest there
may be considerable dispersion in the properties of early-type cluster galaxies
at z~1.5. There is also a population of galaxies whose SEDs are best modelled
by background galaxies at z>2.5.Comment: Accepted to ApJ; 54 pages including 30 figures; 2 color GIF files
available separately; also available from
http://www.astro.utoronto.ca/~hall/thesis.htm
Genetic studies of human apolipoproteins
Apolipoprotein H (APO H) has recently been identified as a structural component of chylomicrons, very low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). Although the precise metabolic function of APO H in lipid metabolism is not certain, it has been suggested that APO H may be involved in triglyceride (TG) metabolism. In addition to the previously described quantitative polymorphism, we have recently detected a common qualitative polymorphism at the APO H structural locus. To test the role of APO H genetic variation in determining lipoprotein and lipid levels, we have estimated the allelic effects of APO H variation on TG, VLDL, LDL, HDL, HDL3, and total cholesterol on 356 Nigerian blacks(189 males, 167 females). While no significant effect of phenotype was observed on lipoprotein levels, the effect of interaction between phenotype and gender was significant. Therefore, data on males and females were analyzed separately using analysis of variance after adjusting for age and body mass index. Logarithmic transformation of pertinent variables was done to bring the distribution of the variables closer to normality. A statistically significant effect of phenotype was observed on triglyceride levels in females only (P<0.05). Further analysis of this phenotypic effect revealed that it is due to the impact of the APO H∗ 3 allele, which raises triglycerides by 9.92 mg/dl as compared to the common allele, APO H ∗2. These findings are in accordance with the postulated role of APO H in triglyceride metabolism. On the basis of its sex-specific effect, we propose a hypothesis that may explain the combined influence of the quantitative and qualitative polymorphisms at the APO H locus on triglyceride levels in females
- …