1,899 research outputs found
How closely do baryons follow dark matter on large scales?
We investigate the large-scale clustering and gravitational interaction of
baryons and dark matter (DM) over cosmic time using a set of collisionless
N-body simulations. Both components, baryons and DM, are evolved from distinct
primordial density and velocity power spectra as predicted by early-universe
physics. We first demonstrate that such two-component simulations require an
unconventional match between force and mass resolution (i.e. force softening on
at least the mean particle separation scale). Otherwise, the growth on any
scale is not correctly recovered because of a spurious coupling between the two
species at the smallest scales. With these simulations, we then demonstrate how
the primordial differences in the clustering of baryons and DM are
progressively diminished over time. In particular, we explicitly show how the
BAO signature is damped in the spatial distribution of baryons and imprinted in
that of DM. This is a rapid process, yet it is still not fully completed at low
redshifts. On large scales, the overall shape of the correlation function of
baryons and DM differs by 2% at z = 9 and by 0.2% at z = 0. The differences in
the amplitude of the BAO peak are approximately a factor of 5 larger: 10% at z
= 9 and 1% at z = 0. These discrepancies are, however, smaller than effects
expected to be introduced by galaxy formation physics in both the shape of the
power spectrum and in the BAO peak, and are thus unlikely to be detected given
the precision of the next generation of galaxy surveys. Hence, our results
validate the standard practice of modelling the observed galaxy distribution
using predictions for the total mass clustering in the Universe.Comment: 9 pages, 6 figures. Replaced with version published in MNRA
The Relationship between Service Learning and Deep Learning
Data analysis from the 2012 National Survey of Student Engagement (NSSE) found that students at Indiana University-Purdue University Indianapolis (IUPUI) who participated in one or more service learning courses had higher mean scores on all three measures of deep learning. These include higher order learning, integrative learning, and reflective learning
Nilpotence in normed MGL-modules
We establish a motivic version of the May Nilpotence Conjecture: if E is a
normed motivic spectrum that satisfies , then also . In words, motivic homology detects vanishing of normed
modules over the algebraic cobordism spectrum.Comment: 17 page
Self-regulation of the endothelin receptor system in choriocarcinoma cells
AbstractThe human trophoblast secretes endothelin-1 (ET-1) and expresses ET receptors. The present study tested whether the transformed BeWo, JAR and JEG-3 choriocarcinoma cells: (1) secrete endothelin-1 (ET-1); (2) express both ET-A and ET-B receptor subtypes; and (3) have the potential to allow for autologous regulation of ET-receptor proteins. The cells were cultured for 24/48 h with or without 10% FCS and, in experiments on receptor regulation, with ET-1 (5–20 nM and 10 μM). ET-1 secretion was measured by RIA and receptor levels by immunoblotting. All cell types secreted ET-1 albeit at different levels and sensitivity to FCS. All cell lines expressed both ET-A (JEG-3>BeWo=JAR) and ET-B (JEG-3=JAR>BeWo) receptor subtypes, which could be up- and downregulated depending on ET-1 concentration, culture time and FCS presence. It is concluded that BeWo, JAR and JEG-3 choriocarcinoma cells secrete ET-1 and express both ET-A and ET-B receptor subtypes. The receptor levels can be regulated by ET-1. This provides the molecular basis for an autocrine system with the potential of autologous regulation of yet unidentified ET-1-induced functions
Biometric Verification Secure Against Malicious Adversaries
Biometric verification has been widely deployed in current authentication
solutions as it proves the physical presence of individuals. To protect the
sensitive biometric data in such systems, several solutions have been developed
that provide security against honest-but-curious (semi-honest) attackers.
However, in practice attackers typically do not act honestly and multiple
studies have shown drastic biometric information leakage in such
honest-but-curious solutions when considering dishonest, malicious attackers.
In this paper, we propose a provably secure biometric verification protocol
to withstand malicious attackers and prevent biometric data from any sort of
leakage. The proposed protocol is based on a homomorphically encrypted log
likelihood-ratio-based (HELR) classifier that supports any biometric modality
(e.g. face, fingerprint, dynamic signature, etc.) encoded as a fixed-length
real-valued feature vector and performs an accurate and fast biometric
recognition. Our protocol, that is secure against malicious adversaries, is
designed from a protocol secure against semi-honest adversaries enhanced by
zero-knowledge proofs. We evaluate both protocols for various security levels
and record a sub-second speed (between s and s) for the protocol
against semi-honest adversaries and between s and s for the
protocol secure against malicious adversaries.Comment: This is a complete reworking and major expansion of our paper
arXiv:1705.09936 * Reworking of original semi-honest protocol and its
security proof * Major expansions: tailored zero-knowledge proofs; efficient
variant of original protocol that we prove secure against malicious
adversaries; extensive experimental evaluation using three different
datasets; in-depth comparison with related wor
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