23,017 research outputs found
Evaluating Maintainability Prejudices with a Large-Scale Study of Open-Source Projects
Exaggeration or context changes can render maintainability experience into
prejudice. For example, JavaScript is often seen as least elegant language and
hence of lowest maintainability. Such prejudice should not guide decisions
without prior empirical validation. We formulated 10 hypotheses about
maintainability based on prejudices and test them in a large set of open-source
projects (6,897 GitHub repositories, 402 million lines, 5 programming
languages). We operationalize maintainability with five static analysis
metrics. We found that JavaScript code is not worse than other code, Java code
shows higher maintainability than C# code and C code has longer methods than
other code. The quality of interface documentation is better in Java code than
in other code. Code developed by teams is not of higher and large code bases
not of lower maintainability. Projects with high maintainability are not more
popular or more often forked. Overall, most hypotheses are not supported by
open-source data.Comment: 20 page
Systems development methods and usability in Norway: An industrial perspective
This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2007 Springer Berlin HeidelbergThis paper investigates the relationship between traditional systems development methodologies and usability, through a survey of 78 Norwegian IT companies. Building on previous research we proposed two hypotheses; (1) that software companies will generally pay lip service to usability, but do not prioritize it in industrial projects, and (2) that systems development methods and usability are perceived as not being integrated. We find support for both hypotheses. Thus, the use of systems development methods is fairly stable, confirming earlier research. Most companies do not use a formal method, and of those who do, the majority use their own method. Generally, the use of methods is rather pragmatic: Companies that do not use formal methods report that they use elements from such methods. Further, companies that use their own method import elements from standardised methods into their own
Regularity of a inverse problem for generic parabolic equations
The paper studies some inverse boundary value problem for simplest parabolic
equations such that the homogenuous Cauchy condition is ill posed at initial
time. Some regularity of the solution is established for a wide class of
boundary value inputs.Comment: 9 page
Identification of SH ro-vibrational lines in R And
We report the identification of SH ro-vibrational lines in the
published high-resolution infrared spectrum of the S-type star, R And. This is
the first astronomical detection of this molecule. The lines show inverse
P-Cygni profiles, indicating infall motion of the molecular layer due to
stellar pulsation. A simple spherical shell model with a constant infall
velocity is adopted to determine the condition of the layer. It is found that a
single excitation temperature of 2200 K reproduces the observed line
intensities satisfactory. SH is located in a layer from 1.0 to ~1.1 stellar
radii, which is moving inward with a velocity of 9 km s-1. These results are
consistent with the previous measurements of CO transitions. The
estimated molecular abundance SH/H is 1x10^-7, consistent with a thermal
equilibrium calculation.Comment: 10 pages, 2 figures. Accepted for publication in ApJ Letter
Entropic trade-off relations for quantum operations
Spectral properties of an arbitrary matrix can be characterized by the
entropy of its rescaled singular values. Any quantum operation can be described
by the associated dynamical matrix or by the corresponding superoperator. The
entropy of the dynamical matrix describes the degree of decoherence introduced
by the map, while the entropy of the superoperator characterizes the a priori
knowledge of the receiver of the outcome of a quantum channel Phi. We prove
that for any map acting on a N--dimensional quantum system the sum of both
entropies is not smaller than ln N. For any bistochastic map this lower bound
reads 2 ln N. We investigate also the corresponding R\'enyi entropies,
providing an upper bound for their sum and analyze entanglement of the
bi-partite quantum state associated with the channel.Comment: 10 pages, 4 figure
On prescribed change of profile for solutions of parabolic equations
Parabolic equations with homogeneous Dirichlet conditions on the boundary are
studied in a setting where the solutions are required to have a prescribed
change of the profile in fixed time, instead of a Cauchy condition. It is shown
that this problem is well-posed in L_2-setting. Existence and regularity
results are established, as well as an analog of the maximum principle
The social, cosmopolitanism and beyond
First, this article will outline the metaphysics of âthe socialâ that implicitly and explicitly connects the work of lassical and contemporary cosmopolitan sociologists as different as Durkheim, Weber, Beck and Luhmann. In a second step, I will show that the cosmopolitan outlook of classical sociology is driven by exclusive differences. In understanding human affairs, both classical sociology and contemporary cosmopolitan sociology reflect a very modernist outlook of epistemological, conceptual, methodological and disciplinary rigour that separates the cultural sphere from the natural objects of concern. I will suggest that classical sociology â in order to be cosmopolitan â is forced (1) to exclude non-social and non-human objects as part of its conceptual and methodological rigour, and (2) consequently and methodologically to rule out the non-social and the non-human. Cosmopolitan sociology imagines âthe socialâ as a global, universal explanatory device to conceive and describe the non-social and non-human. In a third and final step the article draws upon the work of the French sociologist Gabriel Tarde and offers a possible alternative to the modernist social and cultural other-logics of social sciences. It argues for a inclusive conception of âthe socialâ that gives the non-social and non-human a cosmopolitan voice as well
On the unconstrained expansion of a spherical plasma cloud turning collisionless : case of a cloud generated by a nanometer dust grain impact on an uncharged target in space
Nano and micro meter sized dust particles travelling through the heliosphere
at several hundreds of km/s have been repeatedly detected by interplanetary
spacecraft. When such fast moving dust particles hit a solid target in space,
an expanding plasma cloud is formed through the vaporisation and ionisation of
the dust particles itself and part of the target material at and near the
impact point. Immediately after the impact the small and dense cloud is
dominated by collisions and the expansion can be described by fluid equations.
However, once the cloud has reached micro-m dimensions, the plasma may turn
collisionless and a kinetic description is required to describe the subsequent
expansion. In this paper we explore the late and possibly collisionless
spherically symmetric unconstrained expansion of a single ionized ion-electron
plasma using N-body simulations. Given the strong uncertainties concerning the
early hydrodynamic expansion, we assume that at the time of the transition to
the collisionless regime the cloud density and temperature are spatially
uniform. We do also neglect the role of the ambient plasma. This is a
reasonable assumption as long as the cloud density is substantially higher than
the ambient plasma density. In the case of clouds generated by fast
interplanetary dust grains hitting a solid target some 10^7 electrons and ions
are liberated and the in vacuum approximation is acceptable up to meter order
cloud dimensions. ..
A Highly Ordered Faraday-Rotation Structure in the Interstellar Medium
We describe a Faraday-rotation structure in the Interstellar Medium detected
through polarimetric imaging at 1420 MHz from the Canadian Galactic Plane
Survey (CGPS). The structure, at l=91.8, b=-2.5, has an extent of ~2 degree,
within which polarization angle varies smoothly over a range of ~100 degree.
Polarized intensity also varies smoothly, showing a central peak within an
outer shell. This region is in sharp contrast to its surroundings, where
low-level chaotic polarization structure occurs on arcminute scales. The
Faraday-rotation structure has no counterpart in radio total intensity, and is
unrelated to known objects along the line of sight, which include a Lynds
Bright Nebula, LBN 416, and the star cluster M39 (NGC7092). It is interpreted
as a smooth enhancement of electron density. The absence of a counterpart,
either in optical emission or in total intensity, establishes a lower limit to
its distance. An upper limit is determined by the strong beam depolarization in
this direction. At a probable distance of 350 +/- 50 pc, the size of the object
is 10 pc, the enhancement of electron density is 1.7 cm-3, and the mass of
ionized gas is 23 M_sun. It has a very smooth internal magnetic field of
strength 3 microG, slightly enhanced above the ambient field. G91.8-2.5 is the
second such object to be discovered in the CGPS, and it seems likely that such
structures are common in the Magneto-Ionic Medium.Comment: 16 pages, 5 figures, ApJ accepte
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