209 research outputs found
Temporal Discounting Predicts How People Gamble On a Slot Machine
The gambling research literature suggests that temporal discounting may be as-sociated with problem gambling, but research has not demonstrated that rates of discounting predict differences in actual gambling behavior. Thirty eight indi-viduals of different ages and backgrounds were recruited to complete several questionnaires, including a delay-discounting task. They were then given $10 in tokens with the opportunity to gamble on a slot machine. How steeply partici-pants discounted the delayed (hypothetical) monetary rewards was a significant predictor of they gambled. Gender, age, and reported annual income were not significant predictors. To our knowledge, these data are the first to demonstrate that temporal discounting may predict differences in actual gambling behavior (vs. self reports). This predictive relationship has implications for both re-searchers and practitioners
Chemical and kinematical properties of BSSs and HB stars in NGC 6397
We used three sets of high-resolution spectra acquired with the multifiber
facility FLAMES at the Very Large Telescope of the European Southern
Observatory to investigate the chemical and kinematical properties of a sample
of 42 horizontal branch (HB) stars, 18 Blue Straggler Stars (BSSs) and 86 main
sequence turn-off and sub-giant branch stars in the nearby globular cluster NGC
6397. We measured rotational velocities and Fe, O and Mg abundances. All the
unevolved stars in our sample turn out to have low rotational velocites (v sin
i< 10\kms), while HB stars and BSSs show a broad distribution, with values
ranging from 0 to 70 \kms. For HB stars with T<10500 K there is a clear
temperature-oxygen anti-correlation, that can be understood if the star
position along the HB is mainly determined by the He content. The hottest BSSs
and HB stars (with temperatures T>8200 K and T> 10500 K, respectively) also
show significant deviations in their iron abundance with respect to the cluster
metallicity (as traced by the unevolved stars, [Fe/H]=-2.12). While similar
chemical patterns have been already observed in other hot HB stars, this is the
first evidence ever collected for BSSs. We interprete these abundance anomalies
as due to the metal radiative levitation, occurring in stars with shallow or no
convective envelopes
Lithium abundance in the globular cluster M4: from the Turn-Off to the RGB Bump
We present Li and Fe abundances for 87 stars in the GC M4,obtained with
GIRAFFE high-resolution spectra. The targets range from the TO up to the RGB
Bump. The Li abundance in the TO stars is uniform, with an average value
A(Li)=2.30+-0.02 dex,consistent with the upper envelope of Li content measured
in other GCs and in the Halo stars,confirming also for M4 the discrepancy with
the primordial Li abundance predicted by WMAP+BBNS. The iron content of M4 is
[Fe/H]=-1.10+-0.01 dex, with no systematic offsets between dwarf and giant
stars.The behaviour of the Li and Fe abundance along the entire evolutionary
path is incompatible with models with atomic diffusion, pointing out that an
additional turbulent mixing below the convective region needs to be taken into
account,able to inhibit the atomic diffusion.The measured A(Li) and its
homogeneity in the TO stars allow to put strong constraints on the shape of the
Li profile inside the M4 TO stars. The global behaviour of A(Li) with T_{eff}
can be reproduced with different pristine Li abundances, depending on the kind
of adopted turbulent mixing.One cannot reproduce the global trend starting from
the WMAP+BBNS A(Li) and adopting the turbulent mixing described by Richard et
al.(2005) with the same efficiency used by Korn et al.(2006) to explain the Li
content in NGC6397. Such a solution is not able to well reproduce
simultaneously the Li abundance observed in TO and RGB stars.Otherwise,
theWMAP+BBNS A(Li) can be reproduced assuming a more efficient turbulent mixing
able to reach deeper stellar regions where the Li is burned. The cosmological
Li discrepancy cannot be easily solved with the present,poor understanding of
the turbulence in the stellar interiors and a future effort to well understand
the true nature of this non-canonical process is needed.Comment: Accepted for publication in the MNRA
Halo globular clusters observed with AAOmega: dark matter content, metallicity and tidal heating
Globular clusters have proven to be essential to our understanding of many
important astrophysical phenomena. Here we analyse spectroscopic observations
of ten Halo globular clusters to determine their dark matter content, their
tidal heating by the Galactic disc and halo, describe their metallicities and
the likelihood that Newtonian dynamics explain their kinematics. We analyse a
large number of members in all clusters, allowing us to address all these
issues together, and we have included NGC 288 and M30 to overlap with previous
studies. We find that any flattening of the velocity dispersion profiles in the
outer regions of our clusters can be explained by tidal heating. We also find
that all our GCs have M/L_V < 5, therefore, we infer the observed dynamics do
not require dark matter, or a modification of gravity. We suggest that the lack
of tidal heating signatures in distant clusters indicates the Halo is not
triaxial. The isothermal rotations of each cluster are measured, with M4 and
NGC 288 exhibiting rotation at a level of 0.9 +/- 0.1 km/s and 0.25 +/- 0.15
km/s, respectively. We also indirectly measure the tidal radius of NGC 6752,
determining a more realistic figure for this cluster than current literature
values. Lastly, an unresolved and intriguing puzzle is uncovered with regard to
the cooling of the outer regions of all ten clusters.Comment: 12 pages, 8 figures, 1 table. Accepted for publication in MNRAS
Distances and ages of NGC 6397, NGC 6752 and 47 Tuc
Distances and absolute ages for the globular clusters NGC6397, NGC6752, and
47 Tuc are obtained using Main Sequence Fitting. Accurate reddenings and metal
abundances (errors of 0.005 mag and 0.04 dex) are obtained by comparing B-V,
b-y colours and UVES spectra for clusters TO-stars and subgiants with similar
data for Hipparcos subdwarfs, using a reddening free temperature indicator
(Halpha). Errors in distances and ages are 0.07 mag and 1 Gyr. NGC6397 and
NGC6752 have ages of 13.5\pm 1.1 and 13.4\pm 1.1 Gyr, while 47 Tuc is probably
about 2.6 Gyr younger, in agreement with results obtained by techniques
sensitive to relative ages. Considering possible systematic errors, the age of
the oldest globular clusters is 13.4\pm 0.8\pm 0.6 Gyr (random and systematic
errors). This age is fully compatible with WMAP results, and indicates that the
oldest Galactic globular clusters formed within the first 1.7 Gyr after the Big
Bang, corresponding to a redshift of z\geq 2.5, in a standard LambdaCDM model.
The epoch of formation of the (inner halo) globular clusters lasted about 2.6
Gyr, ending at a time corresponding to a redshift of z\geq 1.3. Once combined
with values of Ho given by WMAP and by the HST Key Project, our age estimate
provides a robust upper limit at 95% level of confidence of Omega_M<0.57,
indicating the need for a vacuum energy independent of results from type Ia SNe
and clusters of galaxies. Using cluster distances, we derive a value of
M_V(HB)=(0.22\pm 0.05)([Fe/H]+1.5)+(0.56\pm 0.07) for the zero point of the
relation between the horizontal branch absolute magnitude and metallicity. When
combined with the apparent average luminosity of the RR Lyrae stars in the LMC
by Clementini et al. (2003), this zero point provides a new estimate of the
distance modulus to the LMC: (m-M)o=18.50\pm 0.09.Comment: 16 pages, 5 encapsulated figures, accepted for publication in A&
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Differential Stem and Progenitor Cell Trafficking by Prostaglandin E2
SUMMARY To maintain lifelong production of blood cells, hematopoietic stem cells (HSC) are tightly regulated by inherent programs and extrinsic regulatory signals received from their microenvironmental niche. Long-term repopulating HSC (LT-HSC) reside in several, perhaps overlapping, niches that produce regulatory molecules/signals necessary for homeostasis and increased output following stress/injury 1–5. Despite significant advances in specific cellular or molecular mechanisms governing HSC/niche interactions, little is understood about regulatory function within the intact mammalian hematopoietic niche. Recently, we and others described a positive regulatory role for Prostaglandin E2 (PGE2) on HSC function ex vivo 6,7. While exploring the role of endogenous PGE2 we unexpectedly observed hematopoietic egress after nonsteroidal anti-inflammatory drug (NSAID) treatment. Surprisingly, this was independent of the SDF-1/CXCR4 axis. Stem and progenitor cells were found to have differing mechanisms of egress, with HSC transit to the periphery dependent on niche attenuation and reduction in the retentive molecule osteopontin (OPN). Hematopoietic grafts mobilized with NSAIDs had superior repopulating ability and long-term engraftment. Treatment of non-human primates and healthy human volunteers confirmed NSAID-mediated egress in higher species. PGE2 receptor knockout mice demonstrated that progenitor expansion and stem/progenitor egress resulted from reduced EP4 receptor signaling. These results not only uncover unique regulatory roles for EP4 signaling in HSC retention in the niche but also define a rapidly translatable strategy to therapeutically enhance transplantation
The many possible climates from the Paris Agreement’s aim of 1.5 °C warming
The United Nations’ Paris Agreement includes the aim of pursuing efforts to limit global warming to only 1.5 °C above pre-industrial levels. However, it is not clear what the resulting climate would look like across the globe and over time. Here we show that trajectories towards a ‘1.5 °C warmer world’ may result in vastly different outcomes at regional scales, owing to variations in the pace and location of climate change and their interactions with society’s mitigation, adaptation and vulnerabilities to climate change. Pursuing policies that are considered to be consistent with the 1.5 °C aim will not completely remove the risk of global temperatures being much higher or of some regional extremes reaching dangerous levels for ecosystems and societies over the coming decades
Nonhumans in participatory design
© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. This article examines the role that nonhumans play in participatory design. Research and practice concerned with participatory design mostly focuses on human participants, however nonhumans also participate in the design process and can play a significant role in shaping the process. This article focuses on how nonhumans participate in the design process. An empirical case study is used to illustrate how humans and nonhumans assemble to form networks in order to effect a design. Nonhumans increase the level of participation in a design process. The case study reveals how nonhumans help to maintain, destroy or strengthen networks by substituting, mediating and communicating with humans and often, in doing so, making human actors more or less visible in the process. Nonhumans play a part in configuring the social. Revealing the presence and roles of nonhumans is an important means through which to increase the democracy within the design process
The continuity of effect of schizophrenia polygenic risk score and patterns of cannabis use on transdiagnostic symptom dimensions at first-episode psychosis: findings from the EU-GEI study
Diagnostic categories do not completely reflect the heterogeneous expression of psychosis. Using data from the EU-GEI study, we evaluated the impact of schizophrenia polygenic risk score (SZ-PRS) and patterns of cannabis use on the transdiagnostic expression of psychosis. We analysed first-episode psychosis patients (FEP) and controls, generating transdiagnostic dimensions of psychotic symptoms and experiences using item response bi-factor modelling. Linear regression was used to test the associations between these dimensions and SZ-PRS, as well as the combined effect of SZ-PRS and cannabis use on the dimensions of positive psychotic symptoms and experiences. We found associations between SZ-PRS and (1) both negative (B = 0.18; 95%CI 0.03–0.33) and positive (B = 0.19; 95%CI 0.03–0.35) symptom dimensions in 617 FEP patients, regardless of their categorical diagnosis; and (2) all the psychotic experience dimensions in 979 controls. We did not observe associations between SZ-PRS and the general and affective dimensions in FEP. Daily and current cannabis use were associated with the positive dimensions in FEP (B = 0.31; 95%CI 0.11–0.52) and in controls (B = 0.26; 95%CI 0.06–0.46), over and above SZ-PRS. We provide evidence that genetic liability to schizophrenia and cannabis use map onto transdiagnostic symptom dimensions, supporting the validity and utility of the dimensional representation of psychosis. In our sample, genetic liability to schizophrenia correlated with more severe psychosis presentation, and cannabis use conferred risk to positive symptomatology beyond the genetic risk. Our findings support the hypothesis that psychotic experiences in the general population have similar genetic substrates as clinical disorders
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