1,314 research outputs found
Hybrid Software Development Approaches in Practice: A European Perspective
Agile and traditional development approaches are used in combination in todays software development. To improve the understanding and to provide better guidance for selecting appropriate development approaches, it is important to analyze such combinations in practice. Results obtained from an online survey strongly confirm that hybrid development approaches are widely used in industry. Our results show that hybrid development approaches: (i) have become reality for nearly all companies; (ii) are applied to specific projects even in the presence of company-wide policies for process usage; (iii) are neither planned nor designed but emerge from the evolution of different work practices; and, (iv) are consistently used regardless of company size or industry secto
The persistence landscape and some of its properties
Persistence landscapes map persistence diagrams into a function space, which
may often be taken to be a Banach space or even a Hilbert space. In the latter
case, it is a feature map and there is an associated kernel. The main advantage
of this summary is that it allows one to apply tools from statistics and
machine learning. Furthermore, the mapping from persistence diagrams to
persistence landscapes is stable and invertible. We introduce a weighted
version of the persistence landscape and define a one-parameter family of
Poisson-weighted persistence landscape kernels that may be useful for learning.
We also demonstrate some additional properties of the persistence landscape.
First, the persistence landscape may be viewed as a tropical rational function.
Second, in many cases it is possible to exactly reconstruct all of the
component persistence diagrams from an average persistence landscape. It
follows that the persistence landscape kernel is characteristic for certain
generic empirical measures. Finally, the persistence landscape distance may be
arbitrarily small compared to the interleaving distance.Comment: 18 pages, to appear in the Proceedings of the 2018 Abel Symposiu
Housing Transfer Taxes and Household Mobility: Distortion on the Housing or Labour Market?
Stresses in silos: Comparison between theoretical models and new experiments
We present precise and reproducible mean pressure measurements at the bottom
of a cylindrical granular column. If a constant overload is added, the pressure
is linear in overload and nonmonotonic in the column height. The results are
{\em quantitatively} consistent with a local, linear relation between stress
components, as was recently proposed by some of us. They contradict the
simplest classical (Janssen) approximation, and may pose a rather severe test
of competing models.Comment: 4 pages, 2 figures, final version to appear in Phys. Rev. Let
Exploring CEvNS with NUCLEUS at the Chooz Nuclear Power Plant
Coherent elastic neutrino-nucleus scattering (CENS) offers a unique way
to study neutrino properties and to search for new physics beyond the Standard
Model. Nuclear reactors are promising sources to explore this process at low
energies since they deliver large fluxes of (anti-)neutrinos with typical
energies of a few MeV. In this paper, a new-generation experiment to study
CENS is described. The NUCLEUS experiment will use cryogenic detectors
which feature an unprecedentedly low energy threshold and a time response fast
enough to be operated in above-ground conditions. Both sensitivity to
low-energy nuclear recoils and a high event rate tolerance are stringent
requirements to measure CENS of reactor antineutrinos. A new experimental
site, denoted the Very-Near-Site (VNS) at the Chooz nuclear power plant in
France is described. The VNS is located between the two 4.25 GW
reactor cores and matches the requirements of NUCLEUS. First results of on-site
measurements of neutron and muon backgrounds, the expected dominant background
contributions, are given. In this paper a preliminary experimental setup with
dedicated active and passive background reduction techniques is presented.
Furthermore, the feasibility to operate the NUCLEUS detectors in coincidence
with an active muon-veto at shallow overburden is studied. The paper concludes
with a sensitivity study pointing out the promising physics potential of
NUCLEUS at the Chooz nuclear power plant
A Cryogenic Silicon Interferometer for Gravitational-wave Detection
The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor
Search for gravitational waves from binary inspirals in S3 and S4 LIGO data
We report on a search for gravitational waves from the coalescence of compact
binaries during the third and fourth LIGO science runs. The search focused on
gravitational waves generated during the inspiral phase of the binary
evolution. In our analysis, we considered three categories of compact binary
systems, ordered by mass: (i) primordial black hole binaries with masses in the
range 0.35 M(sun) < m1, m2 < 1.0 M(sun), (ii) binary neutron stars with masses
in the range 1.0 M(sun) < m1, m2 < 3.0 M(sun), and (iii) binary black holes
with masses in the range 3.0 M(sun)< m1, m2 < m_(max) with the additional
constraint m1+ m2 < m_(max), where m_(max) was set to 40.0 M(sun) and 80.0
M(sun) in the third and fourth science runs, respectively. Although the
detectors could probe to distances as far as tens of Mpc, no gravitational-wave
signals were identified in the 1364 hours of data we analyzed. Assuming a
binary population with a Gaussian distribution around 0.75-0.75 M(sun), 1.4-1.4
M(sun), and 5.0-5.0 M(sun), we derived 90%-confidence upper limit rates of 4.9
yr^(-1) L10^(-1) for primordial black hole binaries, 1.2 yr^(-1) L10^(-1) for
binary neutron stars, and 0.5 yr^(-1) L10^(-1) for stellar mass binary black
holes, where L10 is 10^(10) times the blue light luminosity of the Sun.Comment: 12 pages, 11 figure
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