3,396 research outputs found
Bacterial microbiomes from vertically-transmitted fungal inocula of the leaf-cutting ant Atta texana
Microbiome surveys provide clues for the functional roles of symbiotic microbial communities and their hosts. In this study, we elucidated bacterial microbiomes associated with the vertically transmitted fungal inocula (pellets) used by foundress queens of the leaf-cutting ant Atta texana as starter-cultures for new gardens. As reference microbiomes, we also surveyed bacterial microbiomes of foundress queens, gardens and brood of incipient nests. Pseudomonas, Acinetobacter, Propionibacterium and Corynebacterium were consistently present in high abundance in microbiomes. Some pellet and ant samples contained abundant bacteria from an Entomoplasmatales-clade, and a separate PCR-based survey of Entomoplasmatales bacteria in eight attine ant-genera from Brazil placed these bacteria in a monophyletic clade within the bacterial genus Mesoplasma. The attine ant-Mesoplasma association parallels a similar association between a closely related, monophyletic Entomoplasmatales-clade and army ants. Of thirteen A. texana nests surveyed, three nests with exceptionally high Mesoplasma abundance died, whereas the other nests survived. It is unclear whether Mesoplasma was the primary cause of mortality, or Mesoplasma became abundant in moribund nests for non-pathogenic reasons. However, the consistent and geographically widespread presence of Mesoplasma suggests an important functional role in the association with attine ants
WARNING: Physics Envy May Be Hazardous To Your Wealth!
The quantitative aspirations of economists and financial analysts have for
many years been based on the belief that it should be possible to build models
of economic systems - and financial markets in particular - that are as
predictive as those in physics. While this perspective has led to a number of
important breakthroughs in economics, "physics envy" has also created a false
sense of mathematical precision in some cases. We speculate on the origins of
physics envy, and then describe an alternate perspective of economic behavior
based on a new taxonomy of uncertainty. We illustrate the relevance of this
taxonomy with two concrete examples: the classical harmonic oscillator with
some new twists that make physics look more like economics, and a quantitative
equity market-neutral strategy. We conclude by offering a new interpretation of
tail events, proposing an "uncertainty checklist" with which our taxonomy can
be implemented, and considering the role that quants played in the current
financial crisis.Comment: v3 adds 2 reference
Government Spending Cycles: Ideological or Opportunistic?
ands. The time series analysis, covering the period 1953â1993, allows for different types of government spending. In general, spending is inspired by ideological and opportunistic motives: all government expenditure categories show an upward drift during election times and the partisan motives behind government spending are clearly revealed: left-wing cabinets attach greater importance to social security and health care than right-wing cabinets and right-wing cabinets value expenditure on infrastructure and defense more than left-wing parties.
Constructive comments by Frans van Winden, Wilko Letterie, Peter Cornelisse, Arie Ros, André de Moor, Harry ter Rele and an anonymous referee are gratefully acknowledged
The complex TIE between macrophages and angiogenesis
Macrophages are primarily known as phagocytic immune cells, but they also play a role in diverse processes, such as morphogenesis, homeostasis and regeneration. In this review, we discuss the influence of macrophages on angiogenesis, the process of new blood vessel formation from the pre-existing vasculature. Macrophages play crucial roles at each step of the angiogenic cascade, starting from new blood vessel sprouting to the remodelling of the vascular plexus and vessel maturation. Macrophages form promising targets for both pro- and anti-angiogenic treatments. However, to target macrophages, we will first need to understand the mechanisms that control the functional plasticity of macrophages during each of the steps of the angiogenic cascade. Here, we review recent insights in this topic. Special attention will be given to the TIE2-expressing macrophage (TEM), which is a subtype of highly angiogenic macrophages that is able to influence angiogenesis via the angiopoietin-TIE pathway
An analysis of a Heavy Gluino LSP at CDF : The Heavy Gluino Window
In this paper we consider a heavy gluino to be the lightest supersymmetric
particle [LSP]. We investigate the limits on the mass of a heavy gluino LSP,
using the searches for excess events in the jets plus missing momentum channel
in Run I. The neutral and charged R-hadrons, containing a heavy gluino LSP,
have distinct signatures at the Fermilab Tevatron. The range of excluded gluino
masses depends on whether the R-hadron is charged or neutral and the amount of
energy deposited in the hadronic calorimeter. The latter depends on the energy
loss per collision in the calorimeter and the number of collisions; where both
quantities require a model for R-hadron- Nucleon scattering. We show how the
excluded range of gluino mass depends on these parameters. We find that gluinos
with mass in the range between GeV and GeV are excluded by
CDF Run I data. Combined with previous results of Baer et al., which use LEP
data to exclude the range 3 - 2225 GeV, our result demonstrates that an
allowed window for a heavy gluino with mass between 25 and 35 GeV is quite
robust. Finally we discuss the relevant differences of our analysis of Tevatron
data to that of Baer et al.Comment: 36 pages, 11 figures, added an acknowledgemen
Excitation and Abundance of C3 in star forming cores:Herschel/HIFI observations of the sight-lines to W31C and W49N
We present spectrally resolved observations of triatomic carbon (C3) in
several ro-vibrational transitions between the vibrational ground state and the
low-energy nu2 bending mode at frequencies between 1654-1897 GHz along the
sight-lines to the submillimeter continuum sources W31C and W49N, using
Herschel's HIFI instrument. We detect C3 in absorption arising from the warm
envelope surrounding the hot core, as indicated by the velocity peak position
and shape of the line profile. The sensitivity does not allow to detect C3
absorption due to diffuse foreground clouds. From the column densities of the
rotational levels in the vibrational ground state probed by the absorption we
derive a rotation temperature (T_rot) of ~50--70 K, which is a good measure of
the kinetic temperature of the absorbing gas, as radiative transitions within
the vibrational ground state are forbidden. It is also in good agreement with
the dust temperatures for W31C and W49N. Applying the partition function
correction based on the derived T_rot, we get column densities N(C3)
~7-9x10^{14} cm^{-2} and abundance x(C3)~10^{-8} with respect to H2. For W31C,
using a radiative transfer model including far-infrared pumping by the dust
continuum and a temperature gradient within the source along the line of sight
we find that a model with x(C3)=10^{-8}, T_kin=30-50 K, N(C3)=1.5 10^{15}
cm^{-2} fits the observations reasonably well and provides parameters in very
good agreement with the simple excitation analysis.Comment: Accepted for publication in Astronomy and Astrophysics (HIFI first
results issue
Novel EDGE encoding method enhances ability to identify genetic interactions
Assumptions are made about the genetic model of single nucleotide polymorphisms (SNPs) when choosing a traditional genetic encoding: additive, dominant, and recessive. Furthermore, SNPs across the genome are unlikely to demonstrate identical genetic models. However, running SNP-SNP interaction analyses with every combination of encodings raises the multiple testing burden. Here, we present a novel and flexible encoding for genetic interactions, the elastic data-driven genetic encoding (EDGE), in which SNPs are assigned a heterozygous value based on the genetic model they demonstrate in a dataset prior to interaction testing. We assessed the power of EDGE to detect genetic interactions using 29 combinations of simulated genetic models and found it outperformed the traditional encoding methods across 10%, 30%, and 50% minor allele frequencies (MAFs). Further, EDGE maintained a low false-positive rate, while additive and dominant encodings demonstrated inflation. We evaluated EDGE and the traditional encodings with genetic data from the Electronic Medical Records and Genomics (eMERGE) Network for five phenotypes: age-related macular degeneration (AMD), age-related cataract, glaucoma, type 2 diabetes (T2D), and resistant hypertension. A multi-encoding genome-wide association study (GWAS) for each phenotype was performed using the traditional encodings, and the top results of the multi-encoding GWAS were considered for SNP-SNP interaction using the traditional encodings and EDGE. EDGE identified a novel SNP-SNP interaction for age-related cataract that no other method identified: rs7787286 (MAF: 0.041;intergenic region of chromosome 7)-rs4695885 (MAF: 0.34;intergenic region of chromosome 4) with a Bonferroni LRT p of 0.018. A SNP-SNP interaction was found in data from the UK Biobank within 25 kb of these SNPs using the recessive encoding: rs60374751 (MAF: 0.030) and rs6843594 (MAF: 0.34) (Bonferroni LRT p: 0.026). We recommend using EDGE to flexibly detect interactions between SNPs exhibiting diverse action. Author summary Although traditional genetic encodings are widely implemented in genetics research, including in genome-wide association studies (GWAS) and epistasis, each method makes assumptions that may not reflect the underlying etiology. Here, we introduce a novel encoding method that estimates and assigns an individualized data-driven encoding for each single nucleotide polymorphism (SNP): the elastic data-driven genetic encoding (EDGE). With simulations, we demonstrate that this novel method is more accurate and robust than traditional encoding methods in estimating heterozygous genotype values, reducing the type I error, and detecting SNP-SNP interactions. We further applied the traditional encodings and EDGE to biomedical data from the Electronic Medical Records and Genomics (eMERGE) Network for five phenotypes, and EDGE identified a novel interaction for age-related cataract not detected by traditional methods, which replicated in data from the UK Biobank. EDGE provides an alternative approach to understanding and modeling diverse SNP models and is recommended for studying complex genetics in common human phenotypes
Dependence of Quadrupole Strength in the Transition
Models of baryon structure predict a small quadrupole deformation of the
nucleon due to residual tensor forces between quarks or distortions from the
pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through
the dependence of the magnetic (), electric (), and
scalar () multipoles in the
transition. We report new experimental values for the ratios
and over the range = 0.4-1.8 GeV, extracted from
precision data using a truncated multipole expansion.
Results are best described by recent unitary models in which the pion cloud
plays a dominant role.Comment: 5 pages, 5 figures, 1 table. To be published in Phys. Rev. Lett.
(References, figures and table updated, minor changes.
The e p -> e' p eta reaction at and above the S11(1535) baryon resonance
New cross sections for the reaction e p -> ep eta are reported for total
center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q^2 =
0.25--1.5 GeV^2. This large kinematic range allows extraction of important new
information about response functions, photocouplings, and eta N coupling
strengths of baryon resonances. Expanded W coverage shows sharp structure at W
\~ 1.7 GeV; this is shown to come from interference between S and P waves and
can be interpreted in terms of known resonances. Improved values are derived
for the photon coupling amplitude for the S11(1535) resonance.Comment: 11 pages, RevTeX, 5 figures, submitted to Phys. Rev. Let
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