2,085 research outputs found
Testing general relativity using golden black-hole binaries
The coalescences of stellar-mass black-hole binaries through their inspiral,
merger, and ringdown are among the most promising sources for ground-based
gravitational-wave (GW) detectors. If a GW signal is observed with sufficient
signal-to-noise ratio, the masses and spins of the black holes can be estimated
from just the inspiral part of the signal. Using these estimates of the initial
parameters of the binary, the mass and spin of the final black hole can be
uniquely predicted making use of general-relativistic numerical simulations. In
addition, the mass and spin of the final black hole can be independently
estimated from the merger--ringdown part of the signal. If the binary black
hole dynamics is correctly described by general relativity (GR), these
independent estimates have to be consistent with each other. We present a
Bayesian implementation of such a test of general relativity, which allows us
to combine the constraints from multiple observations. Using kludge modified GR
waveforms, we demonstrate that this test can detect sufficiently large
deviations from GR, and outline the expected constraints from upcoming GW
observations using the second-generation of ground-based GW detectors.Comment: 5 pages, 2 fig
Public-Key Encryption with Quantum Keys
In the framework of Impagliazzo's five worlds, a distinction is often made
between two worlds, one where public-key encryption exists (Cryptomania), and
one in which only one-way functions exist (MiniCrypt). However, the boundaries
between these worlds can change when quantum information is taken into account.
Recent work has shown that quantum variants of oblivious transfer and
multi-party computation, both primitives that are classically in Cryptomania,
can be constructed from one-way functions, placing them in the realm of quantum
MiniCrypt (the so-called MiniQCrypt). This naturally raises the following
question: Is it possible to construct a quantum variant of public-key
encryption, which is at the heart of Cryptomania, from one-way functions or
potentially weaker assumptions?
In this work, we initiate the formal study of the notion of quantum
public-key encryption (qPKE), i.e., public-key encryption where keys are
allowed to be quantum states. We propose new definitions of security and
several constructions of qPKE based on the existence of one-way functions
(OWF), or even weaker assumptions, such as pseudorandom function-like states
(PRFS) and pseudorandom function-like states with proof of destruction
(PRFSPD). Finally, to give a tight characterization of this primitive, we show
that computational assumptions are necessary to build quantum public-key
encryption. That is, we give a self-contained proof that no quantum public-key
encryption scheme can provide information-theoretic security.Comment: This submission subsumes arXiv:2303.02080 and arXiv:2303.0536
Does gender matter? A cross-national investigation of primary class-room discipline.
© 2018 Informa UK Limited, trading as Taylor & Francis GroupFewer than 15% of primary school teachers in both Germany and the UK are male. With the on-going international debate about educational performance highlighting the widening gender achievement gap between girl and boy pupils, the demand for more male teachers has become prevalent in educational discourse. Concerns have frequently been raised about the underachievement of boys, with claims that the lack of male ‘role models’ in schools has an adverse effect on boys’ academic motivation and engagement. Although previous research has examined ‘teaching’ as institutional talk, men’s linguistic behaviour in the classroom remains largely ignored, especially in regard to enacting discipline. Using empirical spoken data collected from four primary school classrooms in both the UK and in Germany, this paper examines the linguistic discipline strategies of eight male and eight female teachers using Interactional Sociolinguistics to address the question, does teacher gender matter?Peer reviewedFinal Accepted Versio
Dual Purpose Lyot Coronagraph Masks for Simultaneous High-Contrast Imaging and High-Resolution Wavefront Sensing
Directly imaging Earth-sized exoplanets with a visible-light coronagraph
instrument on a space telescope will require a system that can achieve
raw contrast and maintain it for the duration of observations
(on the order of hours or more). We are designing, manufacturing, and testing
Dual Purpose Lyot coronagraph (DPLC) masks that allow for simultaneous
wavefront sensing and control using out-of-band light to maintain high contrast
in the science focal plane. Our initial design uses a tiered metallic focal
plane occulter to suppress starlight in the transmitted coronagraph channel and
a dichroic-coated substrate to reflect out-of-band light to a wavefront sensing
camera. The occulter design introduces a phase shift such that the reflected
channel is a Zernike wavefront sensor. The dichroic coating allows higher-order
wavefront errors to be detected which is especially critical for compensating
for residual drifts from an actively-controlled segmented primary mirror. A
second-generation design concept includes a metasurface to create
polarization-dependent phase shifts in the reflected beam, which has several
advantages including an extended dynamic range. We will present the focal plane
mask designs, characterization, and initial testing at NASA's High Contrast
Imaging Testbed (HCIT) facility.Comment: To appear in the Proceedings of the SPIE, Techniques and
Instrumentation for Detection of Exoplanets X
On the Lagrangian Realization of Non-Critical -Strings
A large class of non-critical string theories with extended worldsheet gauge
symmetry are described by two coupled, gauged Wess-Zumino-Witten Models. We
give a detailed analysis of the gauge invariant action and in particular the
gauge fixing procedure and the resulting BRST symmetries. The results are
applied to the example of strings.Comment: 19 pages, LaTeX (REVTEX macro's
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