347 research outputs found
On the logical structure of Bell theorems without inequalities
Bell theorems show how to experimentally falsify local realism. Conclusive
falsification is highly desirable as it would provide support for the most
profoundly counterintuitive feature of quantum theory - nonlocality. Despite
the preponderance of evidence for quantum mechanics, practical limits on
detector efficiency and the difficulty of coordinating space-like separated
measurements have provided loopholes for a classical worldview; these loopholes
have never been simultaneously closed. A number of new experiments have
recently been proposed to close both loopholes at once. We show some of these
novel designs fail in the most basic way, by not ruling out local hidden
variable models, and we provide an explicit classical model to demonstrate
this. They share a common flaw, which reveals a basic misunderstanding of how
nonlocality proofs work. Given the time and resources now being devoted to such
experiments, theoretical clarity is essential. Our explanation is presented in
terms of simple logic and should serve to correct misconceptions and avoid
future mistakes. We also show a nonlocality proof involving four participants
which has interesting theoretical properties.Comment: 8 pages, text clarified, explicit LHV model provided for flawed
nonlocality tes
The experience of antiretroviral treatment for Black West African women who are HIV positive and living in London: an interpretative phenomenological analysis
Antiretroviral therapy (ART) offers a powerful intervention in HIV but effectiveness can be compromised by inadequate adherence. This paper is a detailed examination of the experience of medication in a purposively selected group of people living with HIV. In-depth interviews were conducted with 10 HIV positive, West African women of black heritage living in London, UK. This group was of interest since it is the second largest group affected by HIV in the UK. Interviews were subjected to interpretative phenomenological analysis, an idiographic, experiential, qualitative approach. The paper details the womenâs negative experience of treatment. ART can be considered difficult and unrelenting and may be disconnected from the womenâs sense of health or illness. Participantsâ social context often exacerbated the difficulties. Some reported an improvement in their feelings about the medication over time. These findings point to some intrinsic and social motivators which could act as spurs to adherence
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Variability of quasilinear diffusion coefficients for plasmaspheric hiss
In the Outer Radiation Belt, the acceleration and loss of high-energy electrons is largely controlled by wave-particle interactions. Quasilinear diffusion coefficients are an efficient way to capture the small-scale physics of wave-particle interactions due to magnetospheric wave modes such as plasmaspheric hiss. The strength of quasilinear diffusion coefficients as a function of energy and pitch-angle depends on both wave parameters and plasma parameters such as ambient magnetic field strength, plasma number density and composition. For plasmaspheric hiss in the magnetosphere, observations indicate large variations in the wave intensity and wavenormal angle, but less is known about the simultaneous variability of the magnetic field and number density. We use in-situ measurements from the Van Allen Probe mission to demonstrate the variability of selected factors that control the size and shape of pitch-angle diffusion coefficients: wave intensity, magnetic field strength and electron number density. We then compare with the variability of diffusion coefficients calculated individually from co-located and simultaneous groups of measurements. We show that the distribution of the plasmaspheric hiss diffusion coefficients is highly non-Gaussian with large variance, and that the distributions themselves vary strongly across the three phase-space bins studied. In most bins studied, the plasmaspheric hiss diffusion coefficients tend to increase with geomagnetic activity, but our results indicate that new approaches that include natural variability may yield improved parameterizations. We suggest methods like stochastic parameterization of wave-particle interactions could use variability information to improve modelling of the Outer Radiation Belt
The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines
We explore the variability of quasars in the MgII and Hbeta broad emission
lines and UV/optical continuum emission using the Sloan Digital Sky Survey
Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic
study of quasar variability to date: our study includes 29 spectroscopic epochs
from SDSS-RM over months, containing 357 quasars with MgII and 41 quasars
with Hbeta . On longer timescales, the study is also supplemented with
two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional
quasars with MgII and 572 quasars with Hbeta. The MgII emission line is
significantly variable ( 10% on 100-day timescales), a necessary
prerequisite for its use for reverberation mapping studies. The data also
confirm that continuum variability increases with timescale and decreases with
luminosity, and the continuum light curves are consistent with a damped
random-walk model on rest-frame timescales of days. We compare the
emission-line and continuum variability to investigate the structure of the
broad-line region. Broad-line variability shows a shallower increase with
timescale compared to the continuum emission, demonstrating that the broad-line
transfer function is not a -function. Hbeta is more variable than MgII
(roughly by a factor of ), suggesting different excitation mechanisms,
optical depths and/or geometrical configuration for each emission line. The
ensemble spectroscopic variability measurements enabled by the SDSS-RM project
have important consequences for future studies of reverberation mapping and
black hole mass estimation of quasars.Comment: 20 pages, 25 figures. ApJ accepted: minor revisions following referee
repor
The Sloan Digital Sky Survey Reverberation Mapping Project: No Evidence for Evolution in the M-sigma Relation to z~1
We present host stellar velocity dispersion measurements for a sample of 88
broad-line quasars at 0.10.6) from the Sloan Digital Sky Survey
Reverberation Mapping (SDSS-RM) project. High signal-to-noise ratio coadded
spectra (average S/N~30 per 69 km/s pixel) from SDSS-RM allowed decomposition
of the host and quasar spectra, and measurement of the host stellar velocity
dispersions and black hole (BH) masses using the single-epoch (SE) virial
method. The large sample size and dynamic range in luminosity
(L5100=10^(43.2-44.7) erg/s) lead to the first clear detection of a correlation
between SE virial BH mass and host stellar velocity dispersion far beyond the
local universe. However, the observed correlation is significantly flatter than
the local relation, suggesting that there are selection biases in high-z
luminosity-threshold quasar samples for such studies. Our uniform sample and
analysis enable an investigation of the redshift evolution of the M-sigma
relation free of caveats by comparing different samples/analyses at disjoint
redshifts. We do not observe evolution of the M-sigma relation in our sample,
up to z~1, but there is an indication that the relation flattens towards higher
redshifts. Coupled with the increasing threshold luminosity with redshift in
our sample, this again suggests certain selection biases are at work, and
simple simulations demonstrate that a constant M-sigma relation is favored to
z~1. Our results highlight the scientific potential of deep coadded
spectroscopy from quasar monitoring programs, and offer a new path to probe the
co-evolution of BHs and galaxies at earlier times.Comment: replaced with the accepted version (minor changes and updated
references); ApJ in press; changed title to highlight the main resul
Intensive swift and LCO monitoring of PG 1302â102 : active galactic nucleus disk reverberation mapping of a supermassive black hole binary candidate
This work is supported by the NANOGrav National Science Foundation Physics Frontiers Center award No. 2020265 and NASA grant 80NSSC24K0251. Research at UC Irvine was supported by NSF grant AST-1907290. E.M.C. gratefully acknowledges support from the NSF through grant No. AST-1909199.We present an intensive multiwavelength monitoring campaign of the quasar PG 1302â102 with Swift and the Las Cumbres Observatory network telescopes. At z ⌠0.3, it tests the limits of the reverberation mapping (RM) technique in probing the accretion disk around a supermassive black hole (SMBH) and extends the parameter space to high masses and high accretion rates. This is also the first time the RM technique has been applied to test disk structures predicted in the SMBH binary model that has been suggested for this source. PG 1302â102 was observed at a âŒdaily cadence for âŒ9 months in 14 bands spanning from X-ray to UV and optical wavelengths, and it shows moderate to significant levels of variability correlated between wavelengths. We measure the interband time lags, which are consistent with a Ï â λ 4/3 relation as expected from standard disk reprocessing, albeit with large uncertainties. The disk size implied by the lag spectrum is consistent with the expected disk size for its black hole mass within uncertainties. While the source resembles other reverberation-mapped active galactic nuclei in many respects, and we do not find evidence supporting the prevalent hypothesis that it hosts an SMBH binary, we demonstrate the feasibility of studying SMBH binaries from this novel angle and suggest possibilities for the LSST Deep Drilling Fields.Peer reviewe
Intensive Swift and LCO monitoring of PG 1302102: AGN disk reverberation mapping of a supermassive black hole binary candidate
We present an intensive multiwavelength monitoring campaign of the quasar PG
1302102 with Swift and the Las Cumbres Observatory network telescopes. At
, it tests the limits of the reverberation mapping (RM) technique in
probing the accretion disk around a supermassive black hole (SMBH) and extends
the parameter space to high masses and high accretion rates. This is also the
first time the RM technique has been applied to test disk structures predicted
in the SMBH binary model that has been suggested for this source. PG 1302102
was observed at a daily cadence for months in 14 bands spanning
from X-ray to UV and optical wavelengths, and it shows moderate to significant
levels of variability correlated between wavelengths. We measure the inter-band
time lags which are consistent with a relation as
expected from standard disk reprocessing, albeit with large errors. The disk
size implied by the lag spectrum is consistent with the expected disk size for
its black hole mass within uncertainties. While the source resembles other
reverberation-mapped AGN in many respects, and we do not find evidence
supporting the prevalent hypothesis that it hosts an SMBH binary, we
demonstrate the feasibility of studying SMBH binaries from this novel angle and
suggest possibilities for the LSST Deep Drilling Fields.Comment: 11 pages, 5 figures, 4 tables. Accepted for publication in ApJ. The
full dataset will be available with the ApJ articl
Intentional and unintentional medication non-adherence in psoriasis: The role of patientsâ medication beliefs and habit strength
Medication non-adherence is a missed opportunity for therapeutic benefit. We assessed âreal-worldâ levels of self-reported non-adherence to conventional and biologic systemic therapies used for psoriasis and evaluated psychological and biomedical factors associated with non-adherence using multivariable analyses. Latent profile analysis was used to investigate whether patients can be categorized into groups with similar medication beliefs. Latent profile analysis categorizes individuals with similar profiles on a set of continuous variables into discrete groups represented by a categorical latent variable. Eight hundred and eleven patients enrolled in the British Association of Dermatologists Biologic Interventions Register were included. Six hundred and seventeen patients were using a self-administered systemic therapy; 22.4% were classified as ânon-adherentâ (12% intentionally and 10.9% unintentionally). Patients using an oral conventional systemic agent were more likely to be non-adherent compared to those using etanercept or adalimumab (29.2% vs. 16.4%; P †0.001). Latent profile analysis supported a three-group model; all groups held strong beliefs about their need for systemic therapy but differed in levels of medication concerns. Group 1 (26.4% of the sample) reported the strongest concerns, followed by Group 2 (61%), with Group 3 (12.6%) reporting the weakest concerns. Group 1 membership was associated with intentional non-adherence (odds ratio = 2.27, 95% confidence interval = 1.16â4.47) and weaker medication-taking routine or habit strength was associated with unintentional non-adherence (odds ratio = 0.92, 95% confidence interval = 0.89â0.96). Medication beliefs and habit strength are modifiable targets for strategies to improve adherence in psoriasis
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