1,427 research outputs found
A Quantitative Study of Java Software Buildability
Researchers, students and practitioners often encounter a situation when the
build process of a third-party software system fails. In this paper, we aim to
confirm this observation present mainly as anecdotal evidence so far. Using a
virtual environment simulating a programmer's one, we try to fully
automatically build target archives from the source code of over 7,200 open
source Java projects. We found that more than 38% of builds ended in failure.
Build log analysis reveals the largest portion of errors are
dependency-related. We also conduct an association study of factors affecting
build success
Linking partial and quasi dynamical symmetries in rotational nuclei
Background: Quasi dynamical symmetries (QDS) and partial dynamical symmetries
(PDS) play an important role in the understanding of complex systems. Up to now
these symmetry concepts have been considered to be unrelated. Purpose:
Establish a link between PDS and QDS and find an emperical manifestation.
Methods: Quantum number fluctuations and the intrinsic state formalism are used
within the framework of the interacting boson model of nuclei. Results: A
previously unrecognized region of the parameter space of the interacting boson
model that has both O(6) PDS (purity) and SU(3) QDS (coherence) in the ground
band is established. Many rare-earth nuclei approximately satisfying both
symmetry requirements are identified. Conclusions: PDS are more abundant than
previously recognized and can lead to a QDS of an incompatible symmetry.Comment: 5 pages, 4 figures, 1 tabl
Low Space External Memory Construction of the Succinct Permuted Longest Common Prefix Array
The longest common prefix (LCP) array is a versatile auxiliary data structure
in indexed string matching. It can be used to speed up searching using the
suffix array (SA) and provides an implicit representation of the topology of an
underlying suffix tree. The LCP array of a string of length can be
represented as an array of length words, or, in the presence of the SA, as
a bit vector of bits plus asymptotically negligible support data
structures. External memory construction algorithms for the LCP array have been
proposed, but those proposed so far have a space requirement of words
(i.e. bits) in external memory. This space requirement is in some
practical cases prohibitively expensive. We present an external memory
algorithm for constructing the bit version of the LCP array which uses
bits of additional space in external memory when given a
(compressed) BWT with alphabet size and a sampled inverse suffix array
at sampling rate . This is often a significant space gain in
practice where is usually much smaller than or even constant. We
also consider the case of computing succinct LCP arrays for circular strings
The maximum modulus of a trigonometric trinomial
Let Lambda be a set of three integers and let C_Lambda be the space of
2pi-periodic functions with spectrum in Lambda endowed with the maximum modulus
norm. We isolate the maximum modulus points x of trigonometric trinomials T in
C_Lambda and prove that x is unique unless |T| has an axis of symmetry. This
permits to compute the exposed and the extreme points of the unit ball of
C_Lambda, to describe how the maximum modulus of T varies with respect to the
arguments of its Fourier coefficients and to compute the norm of unimodular
relative Fourier multipliers on C_Lambda. We obtain in particular the Sidon
constant of Lambda
(Never) Mind your p's and q's: Von Neumann versus Jordan on the Foundations of Quantum Theory
In two papers entitled "On a new foundation [Neue Begr\"undung] of quantum
mechanics," Pascual Jordan (1927b,g) presented his version of what came to be
known as the Dirac-Jordan statistical transformation theory. As an alternative
that avoids the mathematical difficulties facing the approach of Jordan and
Paul A. M. Dirac (1927), John von Neumann (1927a) developed the modern Hilbert
space formalism of quantum mechanics. In this paper, we focus on Jordan and von
Neumann. Central to the formalisms of both are expressions for conditional
probabilities of finding some value for one quantity given the value of
another. Beyond that Jordan and von Neumann had very different views about the
appropriate formulation of problems in quantum mechanics. For Jordan, unable to
let go of the analogy to classical mechanics, the solution of such problems
required the identication of sets of canonically conjugate variables, i.e., p's
and q's. For von Neumann, not constrained by the analogy to classical
mechanics, it required only the identication of a maximal set of commuting
operators with simultaneous eigenstates. He had no need for p's and q's. Jordan
and von Neumann also stated the characteristic new rules for probabilities in
quantum mechanics somewhat differently. Jordan (1927b) was the first to state
those rules in full generality. Von Neumann (1927a) rephrased them and, in a
subsequent paper (von Neumann, 1927b), sought to derive them from more basic
considerations. In this paper we reconstruct the central arguments of these
1927 papers by Jordan and von Neumann and of a paper on Jordan's approach by
Hilbert, von Neumann, and Nordheim (1928). We highlight those elements in these
papers that bring out the gradual loosening of the ties between the new quantum
formalism and classical mechanics.Comment: New version. The main difference with the old version is that the
introduction has been rewritten. Sec. 1 (pp. 2-12) in the old version has
been replaced by Secs. 1.1-1.4 (pp. 2-31) in the new version. The paper has
been accepted for publication in European Physical Journal
From Einstein's Theorem to Bell's Theorem: A History of Quantum Nonlocality
In this Einstein Year of Physics it seems appropriate to look at an important
aspect of Einstein's work that is often down-played: his contribution to the
debate on the interpretation of quantum mechanics. Contrary to popular opinion,
Bohr had no defence against Einstein's 1935 attack (the EPR paper) on the
claimed completeness of orthodox quantum mechanics. I suggest that Einstein's
argument, as stated most clearly in 1946, could justly be called Einstein's
reality-locality-completeness theorem, since it proves that one of these three
must be false. Einstein's instinct was that completeness of orthodox quantum
mechanics was the falsehood, but he failed in his quest to find a more complete
theory that respected reality and locality. Einstein's theorem, and possibly
Einstein's failure, inspired John Bell in 1964 to prove his reality-locality
theorem. This strengthened Einstein's theorem (but showed the futility of his
quest) by demonstrating that either reality or locality is a falsehood. This
revealed the full nonlocality of the quantum world for the first time.Comment: 18 pages. To be published in Contemporary Physics. (Minor changes;
references and author info added
Isotope shift in the dielectronic recombination of three-electron ^{A}Nd^{57+}
Isotope shifts in dielectronic recombination spectra were studied for Li-like
^{A}Nd^{57+} ions with A=142 and A=150. From the displacement of resonance
positions energy shifts \delta E^{142,150}(2s-2p_1/2)= 40.2(3)(6) meV
(stat)(sys)) and \delta E^{142,150}(2s-2p_3/2) = 42.3(12)(20) meV of 2s-2p_j
transitions were deduced. An evaluation of these values within a full QED
treatment yields a change in the mean-square charge radius of ^{142,150}\delta
= -1.36(1)(3) fm^2. The approach is conceptually new and combines the
advantage of a simple atomic structure with high sensitivity to nuclear size.Comment: 10 pages, 3 figures, accepted for publication in Physical Review
Letter
Direct observation of long-lived isomers in Bi
Long-lived isomers in 212Bi have been studied following 238U projectile
fragmentation at 670 MeV per nucleon. The fragmentation products were injected
as highly charged ions into the GSI storage ring, giving access to masses and
half-lives. While the excitation energy of the first isomer of 212Bi was
confirmed, the second isomer was observed at 1478(30) keV, in contrast to the
previously accepted value of >1910 keV. It was also found to have an extended
Lorentz-corrected in-ring halflife >30 min, compared to 7.0(3) min for the
neutral atom. Both the energy and half-life differences can be understood as
being due a substantial, though previously unrecognised, internal decay branch
for neutral atoms. Earlier shell-model calculations are now found to give good
agreement with the isomer excitation energy. Furthermore, these and new
calculations predict the existence of states at slightly higher energy that
could facilitate isomer de-excitation studies.Comment: published in PRL 110, 12250
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