586 research outputs found
Quality Assurance of Software Applications Using the In Vivo Testing Approach
Software products released into the field typically have some number of residual defects that either were not detected or could not have been detected during testing. This may be the result of flaws in the test cases themselves, incorrect assumptions made during the creation of test cases, or the infeasibility of testing the sheer number of possible configurations for a complex system; these defects may also be due to application states that were not considered during lab testing, or corrupted states that could arise due to a security violation. One approach to this problem is to continue to test these applications even after deployment, in hopes of finding any remaining flaws. In this paper, we present a testing methodology we call in vivo testing, in which tests are continuously executed in the deployment environment. We also describe a type of test we call in vivo tests that are specifically designed for use with such an approach: these tests execute within the current state of the program (rather than by creating a clean slate) without affecting or altering that state from the perspective of the end-user. We discuss the approach and the prototype testing framework for Java applications called Invite. We also provide the results of case studies that demonstrate Invite's effectiveness and efficiency
Generative User-Experience Research for Developing Domain-specific Natural Language Processing Applications
User experience (UX) is a part of human-computer interaction (HCI) research
and focuses on increasing intuitiveness, transparency, simplicity, and trust
for system users. Most of the UX research for machine learning (ML) or natural
language processing (NLP) focuses on a data-driven methodology, i.e., it fails
to focus on users' requirements, and engages domain users mainly for usability
evaluation. Moreover, more typical UX methods tailor the systems towards user
usability, unlike learning about the user needs first. The paper proposes a
methodology for integrating generative UX research into developing domain NLP
applications. Generative UX research employs domain users at the initial stages
of prototype development, i.e., ideation and concept evaluation, and the last
stage for evaluating the change in user value. In the case study, we report the
full-cycle prototype development of a domain-specific semantic search for daily
operations in the process industry. Our case study shows that involving domain
experts increases their interest and trust in the final NLP application.
Moreover, we show that synergetic UX+NLP research efficiently considers data-
and user-driven opportunities and constraints, which can be crucial for NLP
applications in narrow domain
Effect of the stellar spin history on the tidal evolution of close-in planets
We investigate how the evolution of the stellar spin rate affects, and is
affected by, planets in close orbits, via star-planet tidal interactions. To do
this, we used a standard equilibrium tidal model to compute the orbital
evolution of single planets orbiting both Sun-like stars and 0.1 M\odot
M-dwarfs. We tested two stellar spin evolution profiles, one with fast initial
rotation (P=1.2 day) and one with slow initial rotation (P=8 day). We tested
the effect of varying the stellar and planetary dissipation and the planet's
mass and initial orbital radius. Conclusions: Tidal evolution allows to
differentiate the early behaviors of extremely close-in planets orbiting either
a rapidly rotating star or a slowly rotating star. The early spin-up of the
star allows the close-in planets around fast rotators to survive the early
evolution. For planets around M-dwarfs, surviving the early evolution means
surviving on Gyr timescales whereas for Sun-like stars the spin-down brings
about late mergers of Jupiter planets. In light of this study, we can say that
differentiating between one spin evolution from another given the present
position of planets can be very tricky. Unless we can observe some markers of
former evolution it is nearly impossible to distinguish the two very different
spin profiles, let alone intermediate spin profiles. Though some conclusions
can still be drawn from statistical distributions of planets around fully
convective M-dwarfs. However, if the tidal evolution brings about a merger late
in its history it can also entail a noticeable acceleration of the star in late
ages, so that it is possible to have old stars that spin rapidly. This raises
the question of better constraining the age of stars
Consistency between ARPES and STM measurements on SmB
Strongly correlated topological surface states are promising platforms for
next-generation quantum applications, but they remain elusive in real
materials. The correlated Kondo insulator SmB is one of the most promising
candidates, with theoretically predicted heavy Dirac surface states supported
by transport and scanning tunneling microscopy (STM) experiments. However, a
puzzling discrepancy appears between STM and angle-resolved photoemission
(ARPES) experiments on SmB. Although ARPES detects spin-textured surface
states, their velocity is an order of magnitude higher than expected, while the
Dirac point -- the hallmark of any topological system -- can only be inferred
deep within the bulk valence band. A significant challenge is that SmB
lacks a natural cleavage plane, resulting in ordered surface domains limited to
10s of nanometers. Here we use STM to show that surface band bending can shift
energy features by 10s of meV between domains. Starting from our STM spectra,
we simulate the full spectral function as an average over multiple domains with
different surface potentials. Our simulation shows excellent agreement with
ARPES data, and thus resolves the apparent discrepancy between large-area
measurements that average over multiple band-shifted domains and
atomically-resolved measurements within a single domain
Gene transfer into hepatocytes using asialoglycoprotein receptor mediated endocytosis of DNA complexed with an artificial tetra-antennary galactose ligand
We have constructed an artificial ligand for the hepatocyte-specific asialoglycoprotein receptor for the purpose of generating a synthetic delivery system for DNA. This ligand has a tetra-antennary structure, containing four terminal galactose residues on a branched carrier peptide. The carbohydrate residues of this glycopeptide were introduced by reductive coupling of lactose to the alpha- and epsilon-amino groups of the two N-terminal lysines on the carrier peptide. The C-terminus of the peptide, containing a cysteine separated from the branched N-terminus by a 10 amino acid spacer sequence, was used for conjugation to 3-(2-pyridyldithio)propionate-modified polylysine via disulfide bond formation. Complexes containing plasmid DNA bound to these galactose-polylysine conjugates have been used for asialoglycoprotein receptor-mediated transfer of a luciferase gene into human (HepG2) and murine (BNL CL.2) hepatocyte cell lines. Gene transfer was strongly promoted when amphipathic peptides with pH-controlled membrane-disruption activity, derived from the N-terminal sequence of influenza virus hemagglutinin HA-2, were also present in these DNA complexes. Thus, we have essentially borrowed the small functional domains of two large proteins, asialoglycoprotein and hemagglutinin, and assembled them into a supramolecular complex to generate an efficient gene-transfer system
Spin-polarized imaging of strongly interacting fermions in the ferrimagnetic state of Weyl candidate CeBi
CeBi has an intricate magnetic phase diagram whose fully-polarized state has
recently been suggested as a Weyl semimetal, though the role of states in
promoting strong interactions has remained elusive. Here we focus on the
less-studied, but also time-reversal symmetry-breaking ferrimagnetic phase of
CeBi, where our density functional theory (DFT) calculations predict additional
Weyl nodes near the Fermi level . We use spin-polarized scanning
tunneling microscopy and spectroscopy to image the surface ferrimagnetic order
on the itinerant Bi states, indicating their orbital hybridization with
localized Ce states. We observe suppression of this spin-polarized
signature at , coincident with a Fano line shape in the
conductance spectra, suggesting the Bi states partially Kondo screen the
magnetic moments, and this hybridization causes strong Fermi-level
band renormalization. The band flattening is supported by our quasiparticle
interference (QPI) measurements, which also show band splitting in agreement
with DFT, painting a consistent picture of a strongly interacting magnetic Weyl
semimetal
Inference on inspiral signals using LISA MLDC data
In this paper we describe a Bayesian inference framework for analysis of data
obtained by LISA. We set up a model for binary inspiral signals as defined for
the Mock LISA Data Challenge 1.2 (MLDC), and implemented a Markov chain Monte
Carlo (MCMC) algorithm to facilitate exploration and integration of the
posterior distribution over the 9-dimensional parameter space. Here we present
intermediate results showing how, using this method, information about the 9
parameters can be extracted from the data.Comment: Accepted for publication in Classical and Quantum Gravity, GWDAW-11
special issu
Visualizing the atomic-scale origin of metallic behavior in Kondo insulators
A Kondo lattice is often electrically insulating at low temperatures.
However, several recent experiments have detected signatures of bulk
metallicity within this Kondo insulating phase. Here we visualize the
real-space charge landscape within a Kondo lattice with atomic resolution using
a scanning tunneling microscope. We discover nanometer-scale puddles of
metallic conduction electrons centered around uranium-site substitutions in the
heavy-fermion compound URuSi, and around samarium-site defects in the
topological Kondo insulator SmB. These defects disturb the Kondo screening
cloud, leaving behind a fingerprint of the metallic parent state. Our results
suggest that the mysterious 3D quantum oscillations measured in SmB could
arise from these Kondo-lattice defects, although we cannot rule out other
explanations. Our imaging technique could enable the development of
atomic-scale charge sensors using heavy-fermion probes
Rotation symmetry breaking in revealed by angle-resolved photoemission spectroscopy
Using angle-resolved photoemission spectroscopy it is revealed that in the vicinity of optimal doping the electronic structure of La2−xSrxCuO4 cuprate undergoes an electronic reconstruction associated with a wave vector qa=(π,0). The reconstructed Fermi surface and folded band are distinct to the shadow bands observed in BSCCO cuprates and in underdoped La2−xSrxCuO4 with x≤0.12, which shift the primary band along the zone diagonal direction. Furthermore, the folded bands appear only with qa=(π,0) vector, but not with qb=(0,π). We demonstrate that the absence of qb reconstruction is not due to the matrix-element effects in the photoemission process, which indicates the fourfold symmetry is broken in the system
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