3,547 research outputs found
Russian-to-English Homographs
Most dictionaries define homograph in terms of words taken from the same language, saying nothing about words from two different languages involving partially overlapping alphabets (e.g., the English Latin alphabet and the Russian Cyrillic alphabet). For example, in their Dictionary or Linguistics (Littlefield and Adams, 1969), Mario Pei and Frank Gaynor define homograph as a word identical in written form with another given word of the same language, but entirely different in origin, sound, and meaning . In contrast, this paper, in considered conformance with the etymology of the word from the Greek, defines an interlingual homograph to be one of two or more words which are identically written regardless of their meanings, derivation, pronunciation, language membership or alphabet constituency
Russian Alphamagic Squares
It has been twenty-two years since Dutch Mathematician Lee C. F. Sallows defined certain magic squares of numbers to be alphamagic squares. He then wrote: Alphamagic is the word I use to describe any magic array ... that remains magic when all of its entries are replaced by numbers representing the word length, in letters, of their conventional written names (thus one (1) becomes 3). Such an alphamagic array represents an extraordinary confluence of magic in the world of numbers with magic in the world of words
Evolution of the Cluster Correlation Function
We study the evolution of the cluster correlation function and its
richness-dependence from z = 0 to z = 3 using large-scale cosmological
simulations. A standard flat LCDM model with \Omega_m = 0.3 and, for
comparison, a tilted \Omega_m = 1 model, TSCDM, are used. The evolutionary
predictions are presented in a format suitable for direct comparisons with
observations. We find that the cluster correlation strength increases with
redshift: high redshift clusters are clustered more strongly (in comoving
scale) than low redshift clusters of the same mass. The increased correlations
with redshift, in spite of the decreasing mass correlation strength, is caused
by the strong increase in cluster bias with redshift: clusters represent higher
density peaks of the mass distribution as the redshift increases. The
richness-dependent cluster correlation function, presented as the
correlation-scale versus cluster mean separation relation, R_0 - d, is found to
be, remarkably, independent of redshift to z <~ 2 for LCDM and z <~ 1 for TCDM
(for a fixed correlation function slope and cluster mass within a fixed
comoving radius). The non-evolving R_0 - d relation implies that both the
comoving clustering scale and the cluster mean separation increase with
redshift for the same mass clusters so that the R_0 - d relation remains
essentially unchanged. The evolution of the R_0 - d relation from z ~ 0 to z ~
3 provides an important new tool in cosmology; it can be used to break
degeneracies that exist at z ~ 0 and provide precise determination of
cosmological parameters.Comment: AASTeX, 15 pages, including 5 figures, accepted version for
publication in ApJ, vol.603, March 200
Evolution of the Cluster Mass and Correlation Functions in LCDM Cosmology
The evolution of the cluster mass function and the cluster correlation
function from z = 0 to z = 3 are determined using 10^6 clusters obtained from
high-resolution simulations of the current best-fit LCDM cosmology (\Omega_m =
0.27, \sigma_8 = 0.84, h = 0.7). The results provide predictions for
comparisons with future observations of high redshift clusters. A comparison of
the predicted mass function of low redshift clusters with observations from
early Sloan Digital Sky Survey data, and the predicted abundance of massive
distant clusters with observational results, favor a slightly larger amplitude
of mass fluctuations (\sigma_8 = 0.9) and lower density parameter (\Omega_m =
0.2); these values are consistent within 1-\sigma with the current
observational and model uncertainties. The cluster correlation function
strength increases with redshift for a given mass limit; the clusters were more
strongly correlated in the past, due to their increasing bias with redshift -
the bias reaches b = 100 at z = 2 for M > 5 x 10^13 h^-1 M_sun. The
richness-dependent cluster correlation function, represented by the correlation
scale versus cluster mean separation relation, R0-d, is generally consistent
with observations. This relation can be approximated as R_0 = 1.7 d^0.6 h^-1
Mpc for d = 20 - 60 h^-1 Mpc. The R0-d relation exhibits surprisingly little
evolution with redshift for z < 2; this can provide a new test of the current
LCDM model when compared with future observations of high redshift clusters.Comment: 20 pages, 9 figures, accepted for publication in Ap
Intrinsic alignment boosting: Direct measurement of intrinsic alignments in cosmic shear data
Intrinsic alignments constitute the major astrophysical systematic for
cosmological weak lensing surveys. We present a purely geometrical method with
which one can study gravitational shear-intrinsic ellipticity correlations
directly in weak lensing data. Linear combinations of second-order cosmic shear
measures are constructed such that the intrinsic alignment signal is boosted
while suppressing the contribution by gravitational lensing. We then assess the
performance of a specific parametrisation of the weights entering these linear
combinations for three representative survey models. Moreover a relation
between this boosting technique and the intrinsic alignment removal via nulling
is derived. For future all-sky weak lensing surveys with photometric redshift
information the boosting technique yields statistical errors on model
parameters of intrinsic alignments whose order of magnitude is compatible with
current constraints determined from indirect measurements. Parameter biases due
to a residual cosmic shear signal are negligible in case of quasi-spectroscopic
redshifts and remain sub-dominant for typical values of the photometric
redshift scatter. We find good agreement between the performance of the
intrinsic alignment removal based on the boosting technique and standard
nulling methods, possibly indicating a fundamental limit in the separation of
lensing and intrinsic alignment signals.Comment: 15 pages, 7 figures; minor changes to match accepted version;
published in Astronomy and Astrophysic
Reclaiming the political : emancipation and critique in security studies
The critical security studies literature has been marked by a shared commitment towards the politicization of security – that is, the analysis of its assumptions, implications and the practices through which it is (re)produced. In recent years, however, politicization has been accompanied by a tendency to conceive security as connected with a logic of exclusion, totalization and even violence. This has resulted in an imbalanced politicization that weakens critique. Seeking to tackle this situation, the present article engages with contributions that have advanced emancipatory versions of security. Starting with, but going beyond, the so-called Aberystwyth School of security studies, the argument reconsiders the meaning of security as emancipation by making the case for a systematic engagement with the notions of reality and power. This revised version of security as emancipation strengthens critique by addressing political dimensions that have been underplayed in the critical security literature
The removal of shear-ellipticity correlations from the cosmic shear signal: Influence of photometric redshift errors on the nulling technique
Cosmic shear is regarded one of the most powerful probes to reveal the
properties of dark matter and dark energy. To fully utilize its potential, one
has to be able to control systematic effects down to below the level of the
statistical parameter errors. Particularly worrisome in this respect is
intrinsic alignment, causing considerable parameter biases via correlations
between the intrinsic ellipticities of galaxies and the gravitational shear,
which mimic lensing. In an earlier work we have proposed a nulling technique
that downweights this systematic, only making use of its well-known redshift
dependence. We assess the practicability of nulling, given realistic conditions
on photometric redshift information. For several simplified intrinsic alignment
models and a wide range of photometric redshift characteristics we calculate an
average bias before and after nulling. Modifications of the technique are
introduced to optimize the bias removal and minimize the information loss by
nulling. We demonstrate that one of the presented versions is close to optimal
in terms of bias removal, given high quality of photometric redshifts. For
excellent photometric redshift information, i.e. at least 10 bins with a small
dispersion, a negligible fraction of catastrophic outliers, and precise
knowledge about the redshift distributions, one version of nulling is capable
of reducing the shear-intrinsic ellipticity contamination by at least a factor
of 100. Alternatively, we describe a robust nulling variant which suppresses
the systematic signal by about 10 for a very broad range of photometric
redshift configurations. Irrespective of the photometric redshift quality, a
loss of statistical power is inherent to nulling, which amounts to a decrease
of the order 50% in terms of our figure of merit.Comment: 26 pages, including 16 figures; minor changes to match accepted
version; published in Astronomy and Astrophysic
A galaxy populations study of a radio-selected protocluster at z~3.1
We present a population study of several types of galaxies within the
protocluster surrounding the radio galaxy MRC0316-257 at z~3.1. In addition to
the known population of Ly_alpha emitters (LAEs) and [OIII] emitters, we use
colour selection techniques to identify protocluster candidates that are Lyman
break galaxies (LBG) and Balmer break galaxies (BBGs). The radio galaxy field
contains an excess of LBG candidates, with a surface density 1.6\pm0.3 times
larger than found for comparable blank fields. This surface overdensity
corresponds to an LBG volume overdensity of ~8\pm4. The BBG photometric
redshift distribution peaks at the protocluster's redshift, but we detect no
significant surface overdensity of BBG. This is not surprising because a volume
overdensity similar to the LBGs would have resulted in a surface density of
~1.2 that found in the blank field. This could not have been detected in our
sample. Masses and star formation rates of the candidate protocluster galaxies
are determined using SED fitting. These properties are not significantly
different from those of field galaxies. The galaxies with the highest masses
and star formation rates are located near the radio galaxy, indicating that the
protocluster environment influences galaxy evolution at z~3. We conclude that
the protocluster around MRC0316-257 is still in the early stages of formation.Comment: 19 pages, 20 figures, accepted for publication in MNRA
The Calibration of Monochromatic Far-Infrared Star Formation Rate Indicators
(Abridged) Spitzer data at 24, 70, and 160 micron and ground-based H-alpha
images are analyzed for a sample of 189 nearby star-forming and starburst
galaxies to investigate whether reliable star formation rate (SFR) indicators
can be defined using the monochromatic infrared dust emission centered at 70
and 160 micron. We compare recently published recipes for SFR measures using
combinations of the 24 micron and observed H-alpha luminosities with those
using 24 micron luminosity alone. From these comparisons, we derive a reference
SFR indicator for use in our analysis. Linear correlations between SFR and the
70 and 160 micron luminosity are found for L(70)>=1.4x10^{42} erg/s and
L(160)>=2x10^{42} erg/s, corresponding to SFR>=0.1-0.3 M_sun/yr. Below those
two luminosity limits, the relation between SFR and 70 micron (160 micron)
luminosity is non-linear and SFR calibrations become problematic. The
dispersion of the data around the mean trend increases for increasing
wavelength, becoming about 25% (factor ~2) larger at 70 (160) micron than at 24
micron. The increasing dispersion is likely an effect of the increasing
contribution to the infrared emission of dust heated by stellar populations not
associated with the current star formation. The non-linear relation between SFR
and the 70 and 160 micron emission at faint galaxy luminosities suggests that
the increasing transparency of the interstellar medium, decreasing effective
dust temperature, and decreasing filling factor of star forming regions across
the galaxy become important factors for decreasing luminosity. The SFR
calibrations are provided for galaxies with oxygen abundance 12+Log(O/H)>8.1.
At lower metallicity the infrared luminosity no longer reliably traces the SFR
because galaxies are less dusty and more transparent.Comment: 69 pages, 19 figures, 2 tables; accepted for publication on Ap
Intrinsic galaxy shapes and alignments I: Measuring and modelling COSMOS intrinsic galaxy ellipticities
The statistical properties of the ellipticities of galaxy images depend on
how galaxies form and evolve, and therefore constrain models of galaxy
morphology, which are key to the removal of the intrinsic alignment
contamination of cosmological weak lensing surveys, as well as to the
calibration of weak lensing shape measurements. We construct such models based
on the halo properties of the Millennium Simulation and confront them with a
sample of 90,000 galaxies from the COSMOS Survey, covering three decades in
luminosity and redshifts out to z=2. The ellipticity measurements are corrected
for effects of point spread function smearing, spurious image distortions, and
measurement noise. Dividing galaxies into early, late, and irregular types, we
find that early-type galaxies have up to a factor of two lower intrinsic
ellipticity dispersion than late-type galaxies. None of the samples shows
evidence for redshift evolution, while the ellipticity dispersion for late-type
galaxies scales strongly with absolute magnitude at the bright end. The
simulation-based models reproduce the main characteristics of the intrinsic
ellipticity distributions although which model fares best depends on the
selection criteria of the galaxy sample. We observe fewer close-to-circular
late-type galaxy images in COSMOS than expected for a sample of randomly
oriented circular thick disks and discuss possible explanations for this
deficit.Comment: 18 pages, 8 figures; updated simulations and galaxy sample
definition, more galaxy samples analysed; matches version published in MNRA
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