898 research outputs found
Real-world evidence of the collective effects of psychedelic therapy: Evaluating from the grassroots
With a surge in critiques levelled against the evidence generated by randomised controlled trials in the study of psychedelic-assisted therapy (PAT), and the legalization of PAT in select jurisdictions such as Australia, and Oregon and Colorado in the United States, we consider what form the real-world evidence of its effects could take. Specifically, we propose to complement individual-level data-gathering (the usual remit of pharmacovigilance procedures) with evidence of PAT's collective effects. Taking our cue from long-standing claims that psychedelics are agents of social transformation, we draw upon the ‘transformative paradigm’ of evaluation, an approach that is itself oriented around social justice and change vis-à-vis marginalised expertise – or what we approach as ‘the grassroots’. To illustrate the potential of such grassroots evaluations, we offer eight examples of social issues that have been discussed in relation to PAT and psychedelics use and, for each, discuss the kinds of expertise that could be brought into the evaluation team and the kinds of questions that could be asked. We further describe our grassroots approach according to three values inspired by the qualities of grass roots themselves: rhizomatic accountability, dark reflexivity, and more-than-human hosting. We argue that these values align with the contemporary experience, practice, and context of PAT. We hope to generate discussion, innovation, and – ultimately – action toward specific study designs that are adequate to the task of documenting, and working with, the transformative potential of psychedelics in contemporary medicalized societies
A comparison of numerical techniques for determining the parameters of distributed RC networks
Numerical techniques for modeling distributed RC network
The True Incidence of Magnetism among Field White Dwarfs
We study the incidence of magnetism in white dwarfs from three large and
well-observed samples of hot, cool, and nearby white dwarfs in order to test
whether the fraction of magnetic degenerates is biased, and whether it varies
with effective temperature, cooling age, or distance. The magnetic fraction is
considerably higher for the cool sample of Bergeron, Ruiz, and Leggett, and the
Holberg, Oswalt, and Sion sample of local white dwarfs that it is for the
generally-hotter white dwarfs of the Palomar Green Survey. We show that the
mean mass of magnetic white dwarfs in this survey is 0.93 solar masses or more,
so there may be a strong bias against their selection in the magnitude-limited
Palomar Green Survey. We argue that this bias is not as important in the
samples of cool and nearby white dwarfs. However, this bias may not account for
all of the difference in the magnetic fractions of these samples.
It is not clear that the magnetic white dwarfs in the cool and local samples
are drawn from the same population as the hotter PG stars. In particular, two
or threee of the cool sample are low-mass white dwarfs in unresolved binary
systems. Moreover, there is a suggestion from the local sample that the
fractional incidence may increase with decreasing temperature, luminosity,
and/or cooling age. Overall, the true incidence of magnetism at the level of 2
megagauss or greater is at least 10%, and could be higher. Limited studies
capable of detecting lower field strengths down to 10 kilogauss suggest by
implication that the total fraction may be substantially higher than 10%.Comment: 16 pages, 2 figures, Astronomical Journal in press -- Jan 2003 issu
Awry²: Making Space for Experimenting with Form
Could experimenting with form help us to counter – even crack – coloniality? We are hopeful. For us, experimenting with form shimmers with possibilities for (a) decolonising Psychology. Awry² (“Awry-squared”) is a section dedicated to experimenting with form within Critical Psychology and related fields. Aka, where Awry goes awry. In this Introduction, we summarise some shapeshifting possibilities for knowledge, knowing, knowers when experimenting with form. And we overview how, through Awry², we are experimenting with making a space for these possibilities to both breathe and be put to the test
On the Nature of the Peculiar Hot Star in the Young LMC Cluster NGC1818
The blue star reported in the field of the young LMC cluster NGC1818 by Elson
et al. (1998) has the wrong luminosity and radius to be a "luminous white
dwarf" member of the cluster. In addition, unless the effective temperature
quoted by the authors is a drastic underestimate, the luminosity is much too
low for it to be a cluster member in the post-AGB phase. Other possibilities,
including that of binary evolution, are briefly discussed. However, the
implication that the massive main sequence turnoff stars in this cluster can
produce white dwarfs (instead of neutron stars) from single-star evolution
needs to be reconsidered.Comment: 5 pages, no figures, Ap J Letters in pres
On the Spectral Evolution of Cool, Helium-Atmosphere White Dwarfs: Detailed Spectroscopic and Photometric Analysis of DZ Stars
We present a detailed analysis of a large spectroscopic and photometric
sample of DZ white dwarfs based on our latest model atmosphere calculations. We
revise the atmospheric parameters of the trigonometric parallax sample of
Bergeron, Leggett, & Ruiz (12 stars) and analyze 147 new DZ white dwarfs
discovered in the Sloan Digital Sky Survey. The inclusion of metals and
hydrogen in our model atmosphere calculations leads to different atmospheric
parameters than those derived from pure helium models. Calcium abundances are
found in the range from log (Ca/He) = -12 to -8. We also find that fits of the
coolest objects show peculiarities, suggesting that our physical models may not
correctly describe the conditions of high atmospheric pressure encountered in
the coolest DZ stars. We find that the mean mass of the 11 DZ stars with
trigonometric parallaxes, = 0.63 Mo, is significantly lower than that
obtained from pure helium models, = 0.78 Mo, and in much better agreement
with the mean mass of other types of white dwarfs. We determine hydrogen
abundances for 27% of the DZ stars in our sample, while only upper limits are
obtained for objects with low signal-to-noise ratio spectroscopic data. We
confirm with a high level of confidence that the accretion rate of hydrogen is
at least two orders of magnitude smaller than that of metals (and up to five in
some cases) to be compatible with the observations. We find a correlation
between the hydrogen abundance and the effective temperature, suggesting for
the first time empirical evidence of a lower temperature boundary for the
hydrogen screening mechanism. Finally, we speculate on the possibility that the
DZA white dwarfs could be the result of the convective mixing of thin
hydrogen-rich atmospheres with the underlying helium convection zone.Comment: 67 pages, 32 figures, accepted for publication in Ap
The hazards of genotype imputation in chromosomal regions under selection: A case study using the Lactase gene region
Although imputation of missing SNP results has been widely used in genetic studies, claims about the quality and usefulness of imputation have outnumbered the few studies that have questioned its limitations. But it is becoming clear that these limitations are real—for example, disease association signals can be missed in regions of LD breakdown. Here, as a case study, using the chromosomal region of the well-known lactase gene, LCT, we address the issue of imputation in the context of variants that have become frequent in a limited number of modern population groups only recently, due to selection. We study SNPs in a 500 bp region covering the enhancer of LCT, and compare imputed genotypes with directly genotyped data. We examine the haplotype pairs of all individuals with discrepant and missing genotypes. We highlight the nonrandom nature of the allelic errors and show that most incorrect imputations and missing data result from long haplotypes that are evolutionarily closely related to those carrying the derived alleles, while some relate to rare and recombinant haplotypes. We conclude that bias of incorrectly imputed and missing genotypes can decrease the accuracy of imputed results substantially
The Spectra of T Dwarfs. II. Red Optical Data
We present 6300--10100 {\AA} spectra for a sample of 13 T dwarfs observed
using LRIS mounted on the Keck I 10m Telescope. A variety of features are
identified and analyzed, including pressure-broadened K I and Na I doublets;
narrow Cs I and Rb I lines; weak CaH, CrH, and FeH bands; strong HO
absorption; and a possible weak CH band. H emission is detected in
three of the T dwarfs, strong in the previously reported active T dwarf 2MASS
1237+6526 and weak in SDSS 12540122 and 2MASS 1047+2124. None of the T
dwarfs exhibit Li I absorption. Guided by the evolution of optical spectral
features with near-infrared spectral type, we derive a parallel optical
classification scheme, focusing on spectral types T5 to T8, anchored to select
spectral standards. We find general agreement between optical and near-infrared
types for nearly all of the T dwarfs so far observed, including two
earlier-type T dwarfs, within our classification uncertainties (1
subtype). These results suggest that competing gravity and temperature effects
compensate for each other over the 0.6--2.5 \micron spectral region. We
identify one possible means of disentangling these effects by comparing the
strength of the K I red wing to the 9250 {\AA} HO band. One of our objects,
2MASS 0937+2931, exhibits a peculiar spectrum, with a substantial red slope and
relatively strong FeH absorption, both consequences of a metal-deficient
atmosphere. Based on its near-infrared properties and substantial space motion,
this object may be a thick disk or halo brown dwarf.Comment: 22 pages including 9 figures, accepted to ApJ v594 Sept. 200
Analysis of hydrogen-rich magnetic white dwarfs detected in the Sloan Digital Sky Survey
We model the structure of the surface magnetic fields of the hydrogen-rich
white dwarfs in the SDSS. We have calculated a grid of state-of-the-art
theoretical optical spectra of hydrogen-rich magnetic white dwarfs with
magnetic field strengths between 1 MG and 1200 MG for different angles, and for
effective temperatures between 7000 K and 50000 K. We used a least-squares
minimization scheme with an evolutionary algorithm in order to find the
magnetic field geometry best fitting the observed data. We used simple centered
dipoles or dipoles which were shifted along the dipole axis to model the
coadded SDSS fiber spectrum of each object. We have analysed the spectra of all
known magnetic DAs from the SDSS (97 previously published plus 44 newly
discovered) and also investigated the statistical properties of magnetic field
geometries of this sample. The total number of known magnetic white dwarfs
already more than tripled by the SDSS and more objects are expected from a more
systematic search. The magnetic fields span a range between ~1 and 900 MG. Our
results further support the claim that Ap/Bp population is insufficient in
generating the numbers and field strength distributions of the observed MWDs,
and either another source of progenitor types or binary evolution is needed.
Moreover clear indications for non-centered dipoles exist in about ~50% of the
objects which is consistent with the magnetic field distribution observed in
Ap/Bp stars.Comment: 15 pages, accepted for publication in A&A. For online version with
full appendix figures, see
http://www.ari.uni-heidelberg.de/mitarbeiter/bkulebi/papers/12570_online.pd
Multiwavelength Observations of the Hot DB Star PG 0112+104
We present a comprehensive multiwavelength analysis of the hot DB white dwarf
PG 0112+104. Our analysis relies on newly-acquired FUSE observations, on
medium-resolution FOS and GHRS data, on archival high-resolution GHRS
observations, on optical spectrophotometry both in the blue and around Halpha,
as well as on time-resolved photometry. From the optical data, we derive a
self-consistent effective temperature of 31,300+-500 K, a surface gravity of
log g = 7.8 +- 0.1 (M=0.52 Msun), and a hydrogen abundance of log N(H)/N(He) <
-4.0. The FUSE spectra reveal the presence of CII and CIII lines that
complement the previous detection of CII transitions with the GHRS. The
improved carbon abundance in this hot object is log N(C)/N(He) = -6.15 +- 0.23.
No photospheric features associated with other heavy elements are detected. We
reconsider the role of PG 0112+104 in the definition of the blue edge of the
V777 Her instability strip in light of our high-speed photometry, and contrast
our results with those of previous observations carried out at the McDonald
Observatory.Comment: 10 pages in emulateapj, 9 figures, accepted for publication in Ap
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