1,342 research outputs found
Dualizability of automatic algebras
We make a start on one of George McNulty's Dozen Easy Problems: "Which finite
automatic algebras are dualizable?" We give some necessary and some sufficient
conditions for dualizability. For example, we prove that a finite automatic
algebra is dualizable if its letters act as an abelian group of permutations on
its states. To illustrate the potential difficulty of the general problem, we
exhibit an infinite ascending chain of finite automatic algebras that are alternately dualizable and
non-dualizable
SIPS - Screening-Instrument fĂŒr prĂ€menstruelle Symptome*: Die deutsche Version des Premenstrual Symptoms Screening Tool zur Erfassung klinisch relevanter Beschwerden
Zusammenfassung: Hintergrund: PrĂ€menstruelle dysphorische Störungen (PMDS) und schwere prĂ€menstruelle Syndrome (PMS) treten hĂ€ufig auf, bleiben jedoch oft unerkannt und unbehandelt. BegĂŒnstigt wird dies durch das Fehlen eines entsprechenden deutschsprachigen Screening-Instruments. Ziel dieser Studie war es, das englischsprachige Premenstrual Symptoms Screening Tool (PSST) ins Deutsche zu ĂŒbertragen und seine Anwendung zu prĂŒfen. Material und Methoden: Die deutschsprachige Version des PSST wurde als "Screening-Instrument fĂŒr prĂ€menstruelle Symptome" (SIPS) erstellt und ihre GĂŒte an 47 Frauen mit und ohne PMDS/schwerem PMS internetbasiert mittels tĂ€glichen SymptomeinschĂ€tzungen bestimmt. Ergebnisse: Die Retest-ReliabilitĂ€t des SIPS betrug r=0,69, das Cronbachsα 0,924. Als ValiditĂ€tsmaĂ des SIPS zeigten sich signifikante Unterschiede zwischen Frauen mit und ohne PMDS/schwerem PMS, bestimmt durch das SIPS, bezĂŒglich prospektiv erfasster prĂ€menstrueller Symptomatik (F[2,44]=4,52, p<0,001) und SymptomverĂ€nderung (F[2,44]=25,23, p<0,001). Schlussfolgerung: Das SIPS ist reliabel und valide und kann helfen, Frauen mit behandlungsbedĂŒrftigen prĂ€menstruellen Beschwerden zu identifiziere
SIPS - Screening-Instrument fĂŒr prĂ€menstruelle Symptome : Die deutsche Version des Premenstrual Symptoms Screening Tool zur Erfassung klinisch relevanter Beschwerden
Premenstrual Dysphoric Disorder (PMDD) and severe Premenstrual Syndrome (PMS) are common, yet often remain unrecognized and not adequately treated. One reason for this is the lack of a valid German screening instrument. The aim of the present study was to create a German version of the English "premenstrual symptoms screening tool (PSST)" and to verify its applicability. The German version of the PSST was created as "Screening- Instrument fĂŒr PrĂ€menstruelle Symptome (SIPS)" and its reliability and validity estimated based on data from 47 women with and without PMDD/severe PMS, using internet-based daily symptom-ratings. The retest-reliability of the SIPS was r=0.69, Cronbach`s Alpha was 0.924. As indicator of the convergent validity of the SIPS, there were significant differences between women with and without PMDD/severe PMS as identified by the SIPS, with regard to prospectively assessed premenstrual symptomatology (F(2,44)=4.52, p>0.001) and symptom change (F(2,44)=25.23, p>0.001). The SIPS is reliable and valid and may help improving the identification of women who require treatment for their premenstrual symptoms
A Search for Nitrogen Enriched Quasars in the Sloan Digital Sky Survey Early Data Release
A search for nitrogen-rich quasars in the Sloan Digital Sky Survey Early Data
Release (SDSS EDR) catalog has yielded 16 candidates, including five with very
prominent emission, but no cases with nitrogen emission as strong as in
Q0353-383. The quasar Q0353-383 has long been known to have extremely strong
nitrogen intercombination lines at lambda 1486 and lambda 1750 Angstroms,
implying an anomalously high nitrogen abundance of about 15 times solar. It is
still the only one of its kind known. A preliminary search through the EDR
using the observed property of the weak C IV emission seen in Q0353-383
resulted in a sample of 23 objects with unusual emission or absorption-line
properties, including one very luminous redshift 2.5 star-forming galaxy. We
present descriptions, preliminary emission-line measurements, and spectra for
all the objects discussed here.Comment: 20 pages, 5 figures, submitted to AJ; final refereed versio
BLR kinematics and Black Hole Mass in Markarian 6
We present results of the optical spectral and photometric observations of
the nucleus of Markarian 6 made with the 2.6-m Shajn telescope at the Crimean
Astrophysical Observatory. The continuum and emission Balmer line intensities
varied more than by a factor of two during 1992-2008. The lag between the
continuum and Hbeta emission line flux variations is 21.1+-1.9 days. For the
Halpha line the lag is about 27 days but its uncertainty is much larger. We use
Monte-Carlo simulation of the random time series to check the effect of our
data sampling on the lag uncertainties and we compare our simulation results
with those obtained by random subset selection (RSS) method of Peterson et al.
(1998). The lag in the high-velocity wings are shorter than in the line core in
accordance with the virial motions. However, the lag is slightly larger in the
blue wing than in the red wing. This is a signature of the infall gas motion.
Probably the BLR kinematic in the Mrk 6 nucleus is a combination of the
Keplerian and infall motions. The velocity-delay dependence is similar for
individual observational seasons. The measurements of the Hbeta line width in
combination with the reverberation lag permits us to determine the black hole
mass, M_BH=(1.8+-0.2)x10^8 M_sun. This result is consistent with the AGN
scaling relationships between the BLR radius and the optical continuum
luminosity (R_BLR is proportional to L^0.5) as well as with the black-hole
mass-luminosity relationship (M_BH-L) under the Eddington luminosity ratio for
Mrk 6 to be L_bol/L_Edd ~ 0.01.Comment: 17 pages, 10 figures, accepted for publication in MNRA
Predictors and immunological correlates of sublethal mercury exposure in vampire bats
Mercury (Hg) is a pervasive heavy metal that often enters the environment from anthropogenic sources such as gold mining and agriculture. Chronic exposure to Hg can impair immune function, reducing the ability of animals to resist or recover from infections. How Hg influences immunity and susceptibility remains unknown for bats, which appear immunologically distinct from other mammals and are reservoir hosts of many pathogens of importance to human and animal health. We here quantify total Hg (THg) in hair collected from common vampire bats (Desmodus rotundus), which feed on blood and are the main reservoir hosts of rabies virus in Latin America. We examine how diet, sampling site and year, and bat demography influence THg and test the consequences of this variation for eight immune measures. In two populations from Belize, THg concentrations in bats were best explained by an interaction between long-term diet inferred from stable isotopes and year. Bats that foraged more consistently on domestic animals exhibited higher THg. However, relationships between diet and THg were evident only in 2015 but not in 2014, which could reflect recent environmental perturbations associated with agriculture. THg concentrations were low relative to values previously observed in other bat species but still correlated with bat immunity. Bats with higher THg had more neutrophils, weaker bacterial killing ability and impaired innate immunity. These patterns suggest that temporal variation in Hg exposure may impair bat innate immunity and increase susceptibility to pathogens such as bacteria. Unexpected associations between low-level Hg exposure and immune function underscore the need to better understand the environmental sources of Hg exposure in bats and the consequences for bat immunity and susceptibility
Synchronous vs. asynchronous dynamics of diffusion-controlled reactions
An analytical method based on the classical ruin problem is developed to
compute the mean reaction time between two walkers undergoing a generalized
random walk on a 1d lattice. At each time step, either both walkers diffuse
simultaneously with probability (synchronous event) or one of them diffuses
while the other remains immobile with complementary probability (asynchronous
event). Reaction takes place through same site occupation or position exchange.
We study the influence of the degree of synchronicity of the walkers and
the lattice size on the global reaction's efficiency. For odd , the
purely synchronous case () is always the most effective one, while for
even , the encounter time is minimized by a combination of synchronous and
asynchronous events. This new parity effect is fully confirmed by Monte Carlo
simulations on 1d lattices as well as for 2d and 3d lattices. In contrast, the
1d continuum approximation valid for sufficiently large lattices predicts a
monotonic increase of the efficiency as a function of . The relevance of the
model for several research areas is briefly discussed.Comment: 21 pages (including 12 figures and 4 tables), uses revtex4.cls,
accepted for publication in Physica
Gravitational Microlensing of a Reverberating Quasar Broad Line Region - I. Method and Qualitative Results
The kinematics and morphology of the broad emission line region (BELR) of
quasars are the subject of significant debate. The two leading methods for
constraining BELR properties are microlensing and reverberation mapping. Here
we combine these two methods with a study of the microlensing behaviour of the
BELR in Q2237+0305, as a change in continuum emission (a "flare") passes
through it. Beginning with some generic models of the BELR - sphere, bicones,
disk - we slice in velocity and time to produce brightness profiles of the BELR
over the duration of the flare. These are numerically microlensed to determine
whether microlensing of reverberation mapping provides new information about
the properties of BELRs. We describe our method and show images of the models
as they are flaring, and the unlensed and lensed spectra that are produced.
Qualitative results and a discussion of the spectra are given in this paper,
highlighting some effects that could be observed. Our conclusion is that the
influence of microlensing, while not strong, can produce significant observable
effects that will help in differentiating the properties of BELRs.Comment: 17 pages, 14 low resolution figures, 1 table, accepted for MNRAS. v2:
Corrected velocities p16, 8 to 0.08, 9 to 0.0
The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta
We have recently completed a 64-night spectroscopic monitoring campaign at
the Lick Observatory 3-m Shane telescope with the aim of measuring the masses
of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected
masses in the range ~10^6-10^7 M_sun and also the well-studied nearby active
galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including
NGC 5548) showed optical variability of sufficient strength during the
monitoring campaign to allow for a time lag to be measured between the
continuum fluctuations and the response to these fluctuations in the broad
Hbeta emission. We present here the light curves for the objects in this sample
and the subsequent Hbeta time lags for the nine objects where these
measurements were possible. The Hbeta lag time is directly related to the size
of the broad-line region, and by combining the lag time with the measured width
of the Hbeta emission line in the variable part of the spectrum, we determine
the virial mass of the central supermassive black hole in these nine AGNs. The
absolute calibration of the black hole masses is based on the normalization
derived by Onken et al. We also examine the time lag response as a function of
velocity across the Hbeta line profile for six of the AGNs. The analysis of
four leads to ambiguous results with relatively flat time lags as a function of
velocity. However, SBS 1116+583A exhibits a symmetric time lag response around
the line center reminiscent of simple models for circularly orbiting broad-line
region (BLR) clouds, and Arp 151 shows an asymmetric profile that is most
easily explained by a simple gravitational infall model. Further investigation
will be necessary to fully understand the constraints placed on physical models
of the BLR by the velocity-resolved response in these objects.Comment: 24 pages, 16 figures and 13 tables, submitted to Ap
Efficiency of encounter-controlled reaction between diffusing reactants in a finite lattice: topology and boundary effects
The role of dimensionality (Euclidean versus fractal), spatial extent,
boundary effects and system topology on the efficiency of diffusion-reaction
processes involving two simultaneously-diffusing reactants is analyzed. We
present numerically-exact values for the mean time to reaction, as gauged by
the mean walklength before reactive encounter, obtained via application of the
theory of finite Markov processes, and via Monte Carlo simulation. As a general
rule, we conclude that for sufficiently large systems, the efficiency of
diffusion-reaction processes involving two synchronously diffusing reactants
(two-walker case) relative to processes in which one reactant of a pair is
anchored at some point in the reaction space (one walker plus trap case) is
higher, and is enhanced the lower the dimensionality of the system. This
differential efficiency becomes larger with increasing system size and, for
periodic systems, its asymptotic value may depend on the parity of the lattice.
Imposing confining boundaries on the system enhances the differential
efficiency relative to the periodic case, while decreasing the absolute
efficiencies of both two-walker and one walker plus trap processes. Analytic
arguments are presented to provide a rationale for the results obtained. The
insights afforded by the analysis to the design of heterogeneous catalyst
systems are also discussed.Comment: 15 pages, 8 figures, uses revtex4, accepted for publication in
Physica
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