2,789 research outputs found
Matching times of leading and following suggest cooperation through direct reciprocity during V-formation flight in ibis
One conspicuous feature of several larger bird species is their annual migration in V-shaped or echelon formation. When birds are flying in these formations, energy savings can be achieved by using the aerodynamic up-wash produced by the preceding bird. As the leading bird in a formation cannot profit from this up-wash, a social dilemma arises around the question of who is going to fly in front? To investigate how this dilemma is solved, we studied the flight behavior of a flock of juvenile Northern bald ibis (Geronticus eremita) during a human-guided autumn migration. We could show that the amount of time a bird is leading a formation is strongly correlated with the time it can itself profit from flying in the wake of another bird. On the dyadic level, birds match the time they spend in the wake of each other by frequent pairwise switches of the leading position. Taken together, these results suggest that bald ibis cooperate by directly taking turns in leading a formation. On the proximate level, we propose that it is mainly the high number of iterations and the immediacy of reciprocation opportunities that favor direct reciprocation. Finally, we found evidence that the animals' propensity to reciprocate in leading has a substantial influence on the size and cohesion of the flight formations
Adversarial decision-making: Choosing between models constructed by interested parties
In this paper, we characterize adversarial decision-making as a choice between competing interpretations of evidence ("models") constructed by interested parties. We show that if a court cannot perfectly determine which party's model is more likely to have generated the evidence, then adversaries face a tradeoff: a model further away from the best (most likely) interpretation has a lower probability of winning, but also a higher payoff following a win. We characterize equilibrium when both adversaries construct optimal models, and use the characterization to compare adversarial decision-making to an inquisitorial benchmark. We find that adversarial decisions are biased, and the bias favors the party with the less-likely, and more extreme, interpretation of the evidence. Court bias disappears when the court is better able to distinguish between the likelihoods of the competing models, or as the amount of evidence grows
Adversarial decision-making: Choosing between models constructed by interested parties
In this paper, we characterize adversarial decision-making as a choice between competing interpretations of evidence ("models") constructed by interested parties. We show that if a court cannot perfectly determine which party's model is more likely to have generated the evidence, then adversaries face a tradeoff: a model further away from the best (most likely) interpretation has a lower probability of winning, but also a higher payoff following a win. We characterize equilibrium when both adversaries construct optimal models, and use the characterization to compare adversarial decision-making to an inquisitorial benchmark. We find that adversarial decisions are biased, and the bias favors the party with the less-likely, and more extreme, interpretation of the evidence. Court bias disappears when the court is better able to distinguish between the likelihoods of the competing models, or as the amount of evidence grows
Diversity of Artists in Major U.S. Museums
The U.S. art museum sector is grappling with diversity. While previous work
has investigated the demographic diversity of museum staffs and visitors, the
diversity of artists in their collections has remained unreported. We conduct
the first large-scale study of artist diversity in museums. By scraping the
public online catalogs of 18 major U.S. museums, deploying a sample of 10,000
artist records comprising over 9,000 unique artists to crowdsourcing, and
analyzing 45,000 responses, we infer artist genders, ethnicities, geographic
origins, and birth decades. Our results are threefold. First, we provide
estimates of gender and ethnic diversity at each museum, and overall, we find
that 85% of artists are white and 87% are men. Second, we identify museums that
are outliers, having significantly higher or lower representation of certain
demographic groups than the rest of the pool. Third, we find that the
relationship between museum collection mission and artist diversity is weak,
suggesting that a museum wishing to increase diversity might do so without
changing its emphases on specific time periods and regions. Our methodology can
be used to broadly and efficiently assess diversity in other fields.Comment: 15 pages, 2 figures, minor revisions of and enhancements to tex
Expanded Human Blood-Derived γδT Cells Display Potent Antigen-Presentation Functions
Cell-based immunotherapy strategies target tumors directly (via cytolytic effector cells) or aim at mobilizing endogenous anti-tumor immunity. The latter approach includes dendritic cells (DC) most frequently in the form of in vitro cultured peripheral blood monocytes-derived DC. Human blood γδT cells are selective for a single class of non-peptide agonists (“phosphoantigens”) and develop into potent antigen-presenting cells (APC), termed γδT-APC within 1–3 days of in vitro culture. Availability of large numbers of γδT-APC would be advantageous for use as a novel cellular vaccine. We here report optimal γδT cell expansion (>10(7) cells/ml blood) when peripheral blood mononuclear cells (PBMC) from healthy individuals and melanoma patients were stimulated with zoledronate and then cultured for 14 days in the presence of IL-2 and IL-15, yielding γδT cell cultures of variable purity (77 ± 21 and 56 ± 26%, respectively). They resembled effector memory αβT (T(EM)) cells and retained full functionality as assessed by in vitro tumor cell killing as well as secretion of pro-inflammatory cytokines (IFNγ, TNFα) and cell proliferation in response to stimulation with phosphoantigens. Importantly, day 14 γδT cells expressed numerous APC-related cell surface markers and, in agreement, displayed potent in vitro APC functions. Day 14 γδT cells from PBMC of patients with cancer were equally effective as their counterparts derived from blood of healthy individuals and triggered potent CD8(+) αβT cell responses following processing and cross-presentation of simple (influenza M1) and complex (tuberculin purified protein derivative) protein antigens. Of note, and in clear contrast to peripheral blood γδT cells, the ability of day 14 γδT cells to trigger antigen-specific αβT cell responses did not depend on re-stimulation. We conclude that day 14 γδT cell cultures provide a convenient source of autologous APC for use in immunotherapy of patients with various cancers
The Great Observatories All-Sky LIRG Survey: Comparison of Ultraviolet and Far-Infrared Properties
The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete
sample of 202 Luminous Infrared Galaxies (LIRGs) selected from the IRAS Revised
Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction
stages, from isolated galaxies to interacting pairs to late stage mergers. We
present a comparison of the UV and infrared properties of 135 galaxies in GOALS
observed by GALEX and Spitzer. For interacting galaxies with separations
greater than the resolution of GALEX and Spitzer (2-6"), we assess the UV and
IR properties of each galaxy individually. The contribution of the FUV to the
measured SFR ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0
+/- 0.4%. The specific star formation rate of the GOALS sample is extremely
high, with a median value (3.9*10^{-10} yr^{-1}) that is comparable to the
highest specific star formation rates seen in the Spitzer Infrared Nearby
Galaxies Survey sample. We examine the position of each galaxy on the IR
excess-UV slope (IRX-beta) diagram as a function of galaxy properties,
including IR luminosity and interaction stage. The LIRGs on average have
greater IR excesses than would be expected based on their UV colors if they
obeyed the same relations as starbursts with L_IR < 10^{11}L_0 or normal
late-type galaxies. The ratio of L_IR to the value one would estimate from the
IRXg-beta relation published for lower luminosity starburst galaxies ranges
from 0.2 to 68, with a median value of 2.7. A minimum of 19% of the total IR
luminosity in the RBGS is produced in LIRGs and ULIRGs with red UV colors (beta
> 0). Among resolved interacting systems, 32% contain one galaxy which
dominates the IR emission while the companion dominates the UV emission. Only
21% of the resolved systems contain a single galaxy which dominates both
wavelengths.Comment: 37 pages, 10 figures, accepted for publication in Ap
Targeting Iron Acquisition Blocks Infection with the Fungal Pathogens Aspergillus fumigatus and Fusarium oxysporum
Filamentous fungi are an important cause of pulmonary and systemic morbidity and mortality, and also cause corneal
blindness and visual impairment worldwide. Utilizing in vitro neutrophil killing assays and a model of fungal infection of the
cornea, we demonstrated that Dectin-1 dependent IL-6 production regulates expression of iron chelators, heme and
siderophore binding proteins and hepcidin in infected mice. In addition, we show that human neutrophils synthesize
lipocalin-1, which sequesters fungal siderophores, and that topical lipocalin-1 or lactoferrin restricts fungal growth in vivo.
Conversely, we show that exogenous iron or the xenosiderophore deferroxamine enhances fungal growth in infected mice.
By examining mutant Aspergillus and Fusarium strains, we found that fungal transcriptional responses to low iron levels and
extracellular siderophores are essential for fungal growth during infection. Further, we showed that targeting fungal iron
acquisition or siderophore biosynthesis by topical application of iron chelators or statins reduces fungal growth in the
cornea by 60% and that dual therapy with the iron chelator deferiprone and statins further restricts fungal growth by 75%.
Together, these studies identify specific host iron-chelating and fungal iron-acquisition mediators that regulate fungal
growth, and demonstrate that therapeutic inhibition of fungal iron acquisition can be utilized to treat topical fungal
infections
Deep ROC Analysis and AUC as Balanced Average Accuracy to Improve Model Selection, Understanding and Interpretation
Optimal performance is critical for decision-making tasks from medicine to
autonomous driving, however common performance measures may be too general or
too specific. For binary classifiers, diagnostic tests or prognosis at a
timepoint, measures such as the area under the receiver operating
characteristic curve, or the area under the precision recall curve, are too
general because they include unrealistic decision thresholds. On the other
hand, measures such as accuracy, sensitivity or the F1 score are measures at a
single threshold that reflect an individual single probability or predicted
risk, rather than a range of individuals or risk. We propose a method in
between, deep ROC analysis, that examines groups of probabilities or predicted
risks for more insightful analysis. We translate esoteric measures into
familiar terms: AUC and the normalized concordant partial AUC are balanced
average accuracy (a new finding); the normalized partial AUC is average
sensitivity; and the normalized horizontal partial AUC is average specificity.
Along with post-test measures, we provide a method that can improve model
selection in some cases and provide interpretation and assurance for patients
in each risk group. We demonstrate deep ROC analysis in two case studies and
provide a toolkit in Python.Comment: 14 pages, 6 Figures, submitted to IEEE Transactions on Pattern
Analysis and Machine Intelligence (TPAMI), currently under revie
Tracing PAHs and Warm Dust Emission in the Seyfert Galaxy NGC 1068
We present a study of the nearby Seyfert galaxy NGC 1068 using mid- and far-
infrared data acquired with the IRAC, IRS, and MIPS instruments aboard the
Spitzer Space Telescope. The images show extensive 8 um and 24 um emission
coinciding with star formation in the inner spiral approximately 15" (1 kpc)
from the nucleus, and a bright complex of star formation 47" (3 kpc) SW of the
nucleus. The brightest 8 um PAH emission regions coincide remarkably well with
knots observed in an Halpha image. Strong PAH features at 6.2, 7.7, 8.6, and
11.3 um are detected in IRS spectra measured at numerous locations inside,
within, and outside the inner spiral. The IRAC colors and IRS spectra of these
regions rule out dust heated by the AGN as the primary emission source; the
SEDs are dominated by starlight and PAH emission. The equivalent widths and
flux ratios of the PAH features in the inner spiral are generally consistent
with conditions in a typical spiral galaxy ISM. Interior to the inner spiral,
the influence of the AGN on the ISM is evident via PAH flux ratios indicative
of a higher ionization parameter and a significantly smaller mean equivalent
width than observed in the inner spiral. The brightest 8 and 24 um emission
peaks in the disk of the galaxy, even at distances beyond the inner spiral, are
located within the ionization cones traced by [O III]/Hbeta, and they are also
remarkably well aligned with the axis of the radio jets. Although it is
possible that radiation from the AGN may directly enhance PAH excitation or
trigger the formation of OB stars that subsequently excite PAH emission at
these locations in the inner spiral, the orientation of collimated radiation
from the AGN and star formation knots in the inner spiral could be
coincidental. (abridged)Comment: 20 pages, 11 figures; AJ, accepted; full resolution version available
at http://spider.ipac.caltech.edu/staff/jhhowell/astro/howelln1068.pd
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