2,179 research outputs found
Economic choices can be made using only stimulus values
Decision-making often involves choices between different stimuli, each of which is associated with a different physical action. A growing consensus suggests that the brain makes such decisions by assigning a value to each available option and then comparing them to make a choice. An open question in decision neuroscience is whether the brain computes these choices by comparing the values of stimuli directly in goods space or instead by first assigning values to the associated actions and then making a choice over actions. We used a functional MRI paradigm in which human subjects made choices between different stimuli with and without knowledge of the actions required to obtain the different stimuli. We found neural correlates of the value of the chosen stimulus (a postdecision signal) in ventromedial prefrontal cortex before the actual stimulusâaction pairing was revealed. These findings provide support for the hypothesis that the brain is capable of making choices in the space of goods without first transferring values into action space
A large, massive, rotating disk around an isolated young stellar object
We present multi-wavelengths observations and a radiative transfer model of a
newly discovered massive circumstellar disk of gas and dust which is one of the
largest disks known today. Seen almost edge-on, the disk is resolved in
high-resolution near-infrared (NIR) images and appears as a dark lane of high
opacity intersecting a bipolar reflection nebula. Based on molecular line
observations we estimate the distance to the object to be 3.5 kpc. This leads
to a size for the dark lane of ~10500 AU but due to shadowing effects the true
disk size could be smaller. In Spitzer/IRAC 3.6 micron images the elongated
shape of the bipolar reflection nebula is still preserved and the bulk of the
flux seems to come from disk regions that can be detected due to the slight
inclination of the disk. At longer IRAC wavelengths, the flux is mainly coming
from the central regions penetrating directly through the dust lane.
Interferometric observations of the dust continuum emission at millimeter
wavelengths with the SMA confirm this finding as the peak of the unresolved
mm-emission coincides perfectly with the peak of the Spitzer/IRAC 5.8 micron
flux and the center of the dark lane seen in the NIR images. Simultaneously
acquired CO data reveal a molecular outflow along the northern part of the
reflection nebula which seems to be the outflow cavity. An elongated gaseous
disk component is also detected and shows signs of rotation. The emission is
perpendicular to the molecular outflow and thus parallel to but even more
extended than the dark lane in the NIR images. Based on the dust continuum and
the CO observations we estimate a disk mass of up to a few solar masses
depending on the underlying assumptions. Whether the disk-like structure is an
actual accretion disk or rather a larger-scale flattened envelope or pseudodisk
is difficult to discriminate with the current dataset (abridged).Comment: Accepted for publication in ApJ, 29 pages preprint style incl. 10
Figure
Comparison of Two Training Methods Applied to Apple Trees Trained to Slender Spindle During the First Years After Planting
Fibrotic Marker Galectin-3 Identifies Males at Risk of Developing Cancer and Heart Failure
BACKGROUND: Cancer and heart failure (HF) are the leading causes of death in the Western world. Shared mechanisms such as fibrosis may underlie either disease entity, furthermore it is unknown whether this relationship is sex-specific.OBJECTIVES: We sought to investigate how fibrosis-related biomarker galectin-3 (gal-3) aids in identifying individuals at risk for new-onset cancer and HF, and how this differs between sexes.METHODS: Gal-3 was measured at baseline and at 4-year follow-up in 5,786 patients of the PREVEND (Prevention of Renal and Vascular Endstage Disease) study. The total follow-up period was 11.5 years. An increase of â„50% in gal-3 levels between measurements was considered relevant. We performed sex-stratified log-rank tests and Cox regression analyses overall and by sex to evaluate the association of gal-3 over time with both new-onset cancer and new-onset HF.RESULTS: Of the 5,786 healthy participants (50% males), 399 (59% males) developed new-onset cancer, and 192 (65% males) developed new-onset HF. In males, an increase in gal-3 was significantly associated with new-onset cancer (both combined and certain cancer-specific subtypes), after adjusting for age, body mass index, hypertension, smoking status, estimated glomerular filtration rate, diabetes mellitus, triglycerides, coronary artery disease, and C-reactive protein (HR: 1.89; 95% CI: 1.32-2.71; P < 0.001). Similar analyses demonstrated an association with new-onset HF in males (HR: 1.77; 95% CI: 1.07-2.95; P = 0.028). In females, changes in gal-3 over time were neither associated with new-onset cancer nor new-onset HF. CONCLUSIONS: Gal-3, a marker of fibrosis, is associated with new-onset cancer and new-onset HF in males, but not in females.</p
No need for secondary Pneumocystis jirovecii pneumonia prophylaxis in adult people living with HIV from Europe on ART with suppressed viraemia and a CD4 cell count greater than 100 cells/”L
Introduction: Since the beginning of the HIV epidemic in resource-rich countries, Pneumocystis jirovecii pneumonia (PjP) is one of the most frequent opportunistic AIDS-defining infections. The Collaboration of Observational HIV Epidemiological Research Europe (COHERE) has shown that primary Pneumocystis jirovecii Pneumonia (PjP) prophylaxis can be safely withdrawn in patients with CD4 counts of 100 to 200 cells/”L if plasma HIV-RNA is suppressed on combination antiretroviral therapy. Whether this holds true for secondary prophylaxis is not known, and this has proved difficult to determine due to the much lower population at risk. Methods: We estimated the incidence of secondary PjP by including patient data collected from 1998 to 2015 from the COHERE cohort collaboration according to time-updated CD4 counts, HIV-RNA and use of PjP prophylaxis in persons >16 years of age. We fitted a Poisson generalized additive model in which the smoothed effect of CD4 was modelled by a restricted cubic spline, and HIV-RNA was stratified as low (10,000copies/mL). Results: There were 373 recurrences of PjP during 74,295 person-years (py) in 10,476 patients. The PjP incidence in the different plasma HIV-RNA strata differed significantly and was lowest in the low stratum. For patients off prophylaxis with CD4 counts between 100 and 200 cells/”L and HIV-RNA below 400 copies/mL, the incidence of recurrent PjP was 3.9 (95% CI: 2.0 to 5.8) per 1000 py, not significantly different from patients on prophylaxis in the same stratum (1.9, 95% CI: 0.1 to 3.7). Conclusions: HIV viraemia importantly affects the risk of recurrent PjP. In virologically suppressed patients on ART with CD4 counts of 100 to 200/”L, the incidence of PjP off prophylaxis is below 10/1000 py. Secondary PjP prophylaxis may be safely withheld in such patients. While European guidelines recommend discontinuing secondary PjP prophylaxis only if CD4 counts rise above 200 cells/mL, the latest US Guidelines consider secondary prophylaxis discontinuation even in patients with a CD4 count above 100 cells/”L and suppressed viral load. Our results strengthen and support this US recommendation. Keywords: opportunistic infections; Pneumocystis jirovecii pneumonia; prophylaxi
No need for secondary Pneumocystis jirovecii pneumonia prophylaxis in adult people living with HIV from Europe on ART with suppressed viraemia and a CD4 cell count greater than 100 cells/”L
INTRODUCTION: Since the beginning of the HIV epidemic in resource-rich countries, Pneumocystis jirovecii pneumonia (PjP) is one of the most frequent opportunistic AIDS-defining infections. The Collaboration of Observational HIV Epidemiological Research Europe (COHERE) has shown that primary Pneumocystis jirovecii Pneumonia (PjP) prophylaxis can be safely withdrawn in patients with CD4 counts of 100 to 200 cells/”L if plasma HIV-RNA is suppressed on combination antiretroviral therapy. Whether this holds true for secondary prophylaxis is not known, and this has proved difficult to determine due to the much lower population at risk. METHODS: We estimated the incidence of secondary PjP by including patient data collected from 1998 to 2015 from the COHERE cohort collaboration according to time-updated CD4 counts, HIV-RNA and use of PjP prophylaxis in persons >16 years of age. We fitted a Poisson generalized additive model in which the smoothed effect of CD4 was modelled by a restricted cubic spline, and HIV-RNA was stratified as low (10,000copies/mL). RESULTS: There were 373 recurrences of PjP during 74,295 person-years (py) in 10,476 patients. The PjP incidence in the different plasma HIV-RNA strata differed significantly and was lowest in the low stratum. For patients off prophylaxis with CD4 counts between 100 and 200 cells/”L and HIV-RNA below 400 copies/mL, the incidence of recurrent PjP was 3.9 (95% CI: 2.0 to 5.8) per 1000 py, not significantly different from patients on prophylaxis in the same stratum (1.9, 95% CI: 0.1 to 3.7). CONCLUSIONS: HIV viraemia importantly affects the risk of recurrent PjP. In virologically suppressed patients on ART with CD4 counts of 100 to 200/”L, the incidence of PjP off prophylaxis is below 10/1000 py. Secondary PjP prophylaxis may be safely withheld in such patients. While European guidelines recommend discontinuing secondary PjP prophylaxis only if CD4 counts rise above 200 cells/mL, the latest US Guidelines consider secondary prophylaxis discontinuation even in patients with a CD4 count above 100 cells/”L and suppressed viral load. Our results strengthen and support this US recommendation
Evolved Massive Stars at Low-metallicity V. Mass-Loss Rate of Red Supergiant Stars in the Small Magellanic Cloud
We assemble the most complete and clean red supergiant (RSG) sample (2,121
targets) so far in the Small Magellanic Cloud (SMC) with 53 different bands of
data to study the MLR of RSGs. In order to match the observed spectral energy
distributions (SEDs), a theoretical grid of 17,820 Oxygen-rich models
(``normal'' and ``dusty'' grids are half-and-half) is created by the
radiatively-driven wind model of the DUSTY code, covering a wide range of dust
parameters. We select the best model for each target by calculating the minimal
modified chi-square and visual inspection. The resulting MLRs from DUSTY are
converted to real MLRs based on the scaling relation, for which a total MLR of
yr is measured (corresponding to a
dust-production rate of yr), with a
typical MLR of yr for the general population of
the RSGs. The complexity of mass-loss estimation based on the SED is fully
discussed for the first time, indicating large uncertainties based on the
photometric data (potentially up to one order of magnitude or more). The
Hertzsprung-Russell and luminosity versus median absolute deviation diagrams of
the sample indicate the positive relation between luminosity and MLR.
Meanwhile, the luminosity versus MLR diagrams show a ``knee-like'' shape with
enhanced mass-loss occurring above , which may
be due to the degeneracy of luminosity, pulsation, low surface gravity,
convection, and other factors. We derive our MLR relation by using a
third-order polynomial to fit the sample and compare our result with previous
empirical MLR prescriptions. Given that our MLR prescription is based on a much
larger sample than previous determinations, it provides a more accurate
relation at the cool and luminous region of the H-R diagram at low-metallicity
compared to previous studies.Comment: 16 pages, 19 figures, accepted by A&
Trends in Cancer Incidence in Different Antiretroviral Treatment-Eras amongst People with HIV
Despite cancer being a leading comorbidity amongst individuals with HIV, there are limited data assessing cancer trends across different antiretroviral therapy (ART)-eras. We calculated age-standardised cancer incidence rates (IRs) from 2006-2021 in two international cohort collaborations (D:A:D and RESPOND). Poisson regression was used to assess temporal trends, adjusted for potential confounders. Amongst 64,937 individuals (31% ART-naĂŻve at baseline) and 490,376 total person-years of follow-up (PYFU), there were 3763 incident cancers (IR 7.7/1000 PYFU [95% CI 7.4, 7.9]): 950 AIDS-defining cancers (ADCs), 2813 non-ADCs, 1677 infection-related cancers, 1372 smoking-related cancers, and 719 BMI-related cancers (groups were not mutually exclusive). Age-standardised IRs for overall cancer remained fairly constant over time (8.22/1000 PYFU [7.52, 8.97] in 2006-2007, 7.54 [6.59, 8.59] in 2020-2021). The incidence of ADCs (3.23 [2.79, 3.72], 0.99 [0.67, 1.42]) and infection-related cancers (4.83 [4.2, 5.41], 2.43 [1.90, 3.05]) decreased over time, whilst the incidence of non-ADCs (4.99 [4.44, 5.58], 6.55 [5.67, 7.53]), smoking-related cancers (2.38 [2.01, 2.79], 3.25 [2.63-3.96]), and BMI-related cancers (1.07 [0.83, 1.37], 1.88 [1.42, 2.44]) increased. Trends were similar after adjusting for demographics, comorbidities, HIV-related factors, and ART use. These results highlight the need for better prevention strategies to reduce the incidence of NADCs, smoking-, and BMI-related cancers
Optical Intensity Interferometry with the Cherenkov Telescope Array
With its unprecedented light-collecting area for night-sky observations, the
Cherenkov Telescope Array (CTA) holds great potential for also optical stellar
astronomy, in particular as a multi-element intensity interferometer for
realizing imaging with sub-milliarcsecond angular resolution. Such an
order-of-magnitude increase of the spatial resolution achieved in optical
astronomy will reveal the surfaces of rotationally flattened stars with
structures in their circumstellar disks and winds, or the gas flows between
close binaries. Image reconstruction is feasible from the second-order
coherence of light, measured as the temporal correlations of arrival times
between photons recorded in different telescopes. This technique (once
pioneered by Hanbury Brown and Twiss) connects telescopes only with electronic
signals and is practically insensitive to atmospheric turbulence and to
imperfections in telescope optics. Detector and telescope requirements are very
similar to those for imaging air Cherenkov observatories, the main difference
being the signal processing (calculating cross correlations between single
camera pixels in pairs of telescopes). Observations of brighter stars are not
limited by sky brightness, permitting efficient CTA use during also bright-Moon
periods. While other concepts have been proposed to realize kilometer-scale
optical interferometers of conventional amplitude (phase-) type, both in space
and on the ground, their complexity places them much further into the future
than CTA, which thus could become the first kilometer-scale optical imager in
astronomy.Comment: Astroparticle Physics, in press; 47 pages, 10 figures, 124 reference
Transiting Exoplanet Studies and Community Targets for JWST's Early Release Science Program
The James Webb Space Telescope will revolutionize transiting exoplanet
atmospheric science due to its capability for continuous, long-duration
observations and its larger collecting area, spectral coverage, and spectral
resolution compared to existing space-based facilities. However, it is unclear
precisely how well JWST will perform and which of its myriad instruments and
observing modes will be best suited for transiting exoplanet studies. In this
article, we describe a prefatory JWST Early Release Science (ERS) program that
focuses on testing specific observing modes to quickly give the community the
data and experience it needs to plan more efficient and successful future
transiting exoplanet characterization programs. We propose a multi-pronged
approach wherein one aspect of the program focuses on observing transits of a
single target with all of the recommended observing modes to identify and
understand potential systematics, compare transmission spectra at overlapping
and neighboring wavelength regions, confirm throughputs, and determine overall
performances. In our search for transiting exoplanets that are well suited to
achieving these goals, we identify 12 objects (dubbed "community targets") that
meet our defined criteria. Currently, the most favorable target is WASP-62b
because of its large predicted signal size, relatively bright host star, and
location in JWST's continuous viewing zone. Since most of the community targets
do not have well-characterized atmospheres, we recommend initiating preparatory
observing programs to determine the presence of obscuring clouds/hazes within
their atmospheres. Measurable spectroscopic features are needed to establish
the optimal resolution and wavelength regions for exoplanet characterization.
Other initiatives from our proposed ERS program include testing the instrument
brightness limits and performing phase-curve observations.(Abridged)Comment: This is a white paper that originated from an open discussion at the
Enabling Transiting Exoplanet Science with JWST workshop held November 16 -
18, 2015 at STScI (http://www.stsci.edu/jwst/science/exoplanets). Accepted
for publication in PAS
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