3,309,663 research outputs found
The last line effect explained
Micro-clones are tiny duplicated pieces of code; they typically comprise only few statements or lines. In this paper, we study the “Last Line Effect,” the phenomenon that the last line or statement in a micro-clone is much more likely to contain an error than the previous lines or statements. We do this by analyzing 219 open source projects and reporting on 263 faulty micro-clones and interviewing six authors of real-world faulty micro-clones. In an interdisciplinary collaboration, we examine the underlying psychological mechanisms for the presence of these relatively trivial errors. Based on the interviews and further technical analyses, we suggest that so-called “action slips” play a pivotal role for the existence of the last line effect: Developers’ attention shifts away at the end of a micro-clone creation task due to noise and the routine nature of the task. Moreover, all micro-clones whose origin we could determine were introduced in unusually large commits. Practitioners benefit from this knowledge twofold: 1) They can spot situations in which they are likely to introduce a faulty micro-clone and 2) they can use PVS-Studio, our automated micro-clone detector, to help find erroneous micro-clones
Use of dynamical coupling for improved quantum state transfer
We propose a method to improve quantum state transfer in transmission lines.
The idea is to localize the information on the last qubit of a transmission
line, by dynamically varying the coupling constants between the first and the
last pair of qubits. The fidelity of state transfer is higher then in a chain
with fixed coupling constants. The effect is stable against small fluctuations
in the system parameters.Comment: 5 pages, 7 figure
On kinks and other travelling-wave solutions of a modified sine-Gordon equation
We give an exhaustive, non-perturbative classification of exact
travelling-wave solutions of a perturbed sine-Gordon equation (on the real line
or on the circle) which is used to describe the Josephson effect in the theory
of superconductors and other remarkable physical phenomena. The perturbation of
the equation consists of a constant forcing term and a linear dissipative term.
On the real line candidate orbitally stable solutions with bounded energy
density are either the constant one, or of kink (i.e. soliton) type, or of
array-of-kinks type, or of "half-array-of-kinks" type. While the first three
have unperturbed analogs, the last type is essentially new. We also propose a
convergent method of successive approximations of the (anti)kink solution based
on a careful application of the fixed point theorem.Comment: Latex file, 25 pages, 4 figures. Final version to appear in
"Meccanica
Genistein induces a protective immunomodulatory effect in a mouse model of cervical cancer
Background: Genistein (GEN), a naturally occurring flavonoid present in soy bean, has attracted scientific interest for its possible benefits in cancer. Objective: The potential immunomodulatory effects of genistein on the immune system and against TC-1 tumor cell line were evaluated in adult female C57BL/6 mice. Methods: Mice were treated with GEN 10 days before to 10 days after the tumor induction. Thirty days after the last GEN treatment, lymphocyte proliferation, Lactase Dehydrogenase (LDH) cytolytic activity and cytokine secretion were analyzed in GEN and control groups. Results: The results showed that ingestion of genistein significantly increased lymphocyte proliferation and LDH release. Furthermore, the treatment with genistein also caused a significant increment in interferon gamma (IFN-γ). In addition, the treatment achieved significant therapeutic effect in tumor models compared to the control group. These results indicated that the effect of GEN on tumor growth may be attributed to its effect on lymphocyte proliferation, cytolytic activity and IFN-γ production. Conclusion: These results demonstrate that GEN exerts an immunomodulatory effect in a mouse model of Human Papillomavirus (HPV) associated-cervical cancer
Wind-wind collision in the eta Carinae binary system - III. The HeII 4686 line profile
We modeled the HeII 4686 line profiles observed in the eta Carinae binary
system close to the 2003.5 spectroscopic event, assuming that they were formed
in the shocked gas that flows at both sides of the contact surface formed by
wind-wind collision. We used a constant flow velocity and added turbulence in
the form of a gaussian velocity distribution. We allowed emission from both the
primary and secondary shocks but introduced infinite opacity at the contact
surface, implying that only the side of the contact cone visible to the
observer contributed to the line profile. Using the orbital parameters of the
binary system derived from the 7 mm light curve during the last spectroscopic
event (Paper II) we were able to reproduce the line profiles obtained with the
HST at different epochs, as well as the line mean velocities obtained with
ground based telescopes. A very important feature of our model is that the line
profile depends on the inclination of the orbital plane; we found that to
explain the latitude dependent mean velocity of the line, scattered into the
line of sight by the Homunculus, the orbit inclination should be close to 90
degrees, meaning that it does not lie in the Homunculus equatorial plane, as
usually assumed. This inclination, together with the relative position of the
stars during the spectroscopic events, allowed us to explain most of the
observational features, like the variation of the Purple Haze with the orbital
phase, and to conciliate the X-ray absorption with the postulated shell effect
used to explain the optical and UV light curves.Comment: to appear in the MNRA
Incentive Effects in Asymmetric Tournaments Empirical Evidence from the German Hockey League
Following tournament theory, incentives will be rather low if the contestants of a tournament are heterogeneous. We empirically test this prediction using a large dataset from the German Hockey League. Our results show that indeed the intensity of a game is lower if the teams are more heterogeneous. This effect can be observed for the game as a whole as well as for the ?rst and last third. When dividing the teams in the dataset into favorites and underdogs, we only observe a reduction of effort provision from favorite teams. As the number of games per team changes between different seasons, we can also investigate the effect of a changing spread between winner and loser prize. In line with theory, teams reduce effort if the spread declines. Interestingly, effort is also sensitive to the total number of teams in the league even if the price spread remains unchanged
Last but not Least: Additional Positional Effects on Citation and Readership in arXiv
We continue investigation of the effect of position in announcements of newly
received articles, a single day artifact, with citations received over the
course of ensuing years. Earlier work [arXiv:0907.4740, arXiv:0805.0307]
focused on the "visibility" effect for positions near the beginnings of
announcements, and on the "self-promotion" effect associated to authors
intentionally aiming for these positions, with both found correlated to a later
enhanced citation rate. Here we consider a "reverse-visibility" effect for
positions near the ends of announcements, and on a "procrastination" effect
associated to submissions made within the 20 minute period just before the
daily deadline. For two large subcommunities of theoretical high energy
physics, we find a clear "reverse-visibility" effect, in which articles near
the ends of the lists receive a boost in both short-term readership and
long-term citations, almost comparable in size to the "visibility" effect
documented earlier. For one of those subcommunities, we find an additional
"procrastination" effect, in which last position articles submitted shortly
before the deadline have an even higher citation rate than those that land more
accidentally in that position. We consider and eliminate geographic effects as
responsible for the above, and speculate on other possible causes, including
"oblivious" and "nightowl" effects.Comment: 13p, appeared JASIST on-line first (12 Oct 2010
Effect of vegetation on sound fields in idealised urban open spaces
Noise pollution is a major environmental problem within the EU and during the last years vegetation was examined for its benefits in increasing health and well-being of citizens from different viewpoints, including noise control and soundscape enhancement. This work focuses on numerical simulations to investigate the effectiveness of vegetation for controlling sound fields, especially in terms of the abatement of traffic noise. Two idealised urban squares were studied, one rectangular and one octagonal. Three plant types, climbing plants (ivy), living green walls with soil substrate and plants in pots (nephrolepis exaltata), were used in this investigation, based on their measured properties in laboratory, and four aspects of the use of vegetation were evaluated: effect of the amount of vegetation, effect of changing in the scattering coefficient of vegetation, effect of vegetation in different receiver positions and effect of vegetation on different groups of receivers. Parametric studies on the determination of a line source and on the definition of sound power levels referred to traffic noise were also developed. Three simulation tools were used, namely CATT-Acoustic®, CRR (Combined Ray-tracing and Radiosity) and Odeon
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