301 research outputs found
Towards a software product line of trie-based collections
Collection data structures in standard libraries of programming languages are designed to excel for the average case by carefully balancing memory footprint and runtime performance. These implicit design decisions and hard-coded trade-offs do constrain users from using an optimal variant for a given problem. Although a wide range of specialized collections is available for the Java Virtual Machine (JVM), they introduce yet another dependency and complicate user adoption by requiring specific Application Program Interfaces (APIs) incompatible with the standard library. A product line for collection data structures would relieve library designers from optimizing for the general case. Furthermore, a product line allows evolving the potentially large code base of a collection family efficiently. The challenge is to find a small core framework for collection data structures which covers all variations without exhaustively listing them, while supporting good performance at the same time. We claim that the concept of Array Mapped Tries (AMTs) embodies a high degree of commonality in the sub-domain of immutable collection data structures. AMTs are flexible enough to cover most of the variability, while minimizing code bloat in the generator and the generated code. We implemented a Data Structure Code Generator (DSCG) that emits immutable collections based on an AMT skeleton foundation. The generated data structures outperform competitive handoptimized implementations, and the generator still allows for customization towards specific workloads
Generic Model Refactorings
Many modeling languages share some common concepts and principles. For example, Java, MOF, and UML share some aspects of the concepts\ud
of classes, methods, attributes, and inheritance. However, model\ud
transformations such as refactorings specified for a given language\ud
cannot be readily reused for another language because their related\ud
metamodels may be structurally different. Our aim is to enable a\ud
flexible reuse of model transformations across various metamodels.\ud
Thus, in this paper, we present an approach allowing the specification\ud
of generic model transformations, in particular refactorings, so\ud
that they can be applied to different metamodels. Our approach relies\ud
on two mechanisms: (1) an adaptation based mainly on the weaving\ud
of aspects; (2) the notion of model typing, an extension of object\ud
typing in the model-oriented context. We validated our approach by\ud
performing some experiments that consisted of specifying three well\ud
known refactorings (Encapsulate Field, Move Method, and Pull Up Method)\ud
and applying each of them onto three different metamodels (Java,\ud
MOF, and UML)
Audience responses to representations of family-assisted suicide on British television
Reflecting on different generic conventions, this study highlights the strengths and weaknesses of documentaries and soap operas in addressing the societal and the personal dimensions of family-assisted suicide. Based on an analysis of YouTube user comments, this study compares how audience members respond to representations of family-assisted suicide in British documentaries and soap operas broadcast between 2010 and 2016. The thematic analysis of comments shows key differences between audience engagement with factual and fictional representations. Markers of a political engagement with this sensitive social issue occur more frequently in comments on documentaries than in comments on soap operas. Comments on soap operas are frequently expressions of emotion, or displays of specialist soap opera knowledge
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Convective transport of formaldehyde to the upper troposphere and lower stratosphere and associated scavenging in thunderstorms over the central United States during the 2012DC3 study
Two-photon quantum walks in an elliptical direct-write waveguide array
Integrated optics provides an ideal test bed for the emulation of quantum
systems via continuous-time quantum walks. Here we study the evolution of
two-photon states in an elliptic array of waveguides. We characterise the
photonic chip via coherent-light tomography and use the results to predict
distinct differences between temporally indistinguishable and distinguishable
two-photon inputs which we then compare with experimental observations. Our
work highlights the feasibility for emulation of coherent quantum phenomena in
three-dimensional waveguide structures.Comment: 8 pages, 7 figure
Quantum computing with mixed states
We discuss a model for quantum computing with initially mixed states.
Although such a computer is known to be less powerful than a quantum computer
operating with pure (entangled) states, it may efficiently solve some problems
for which no efficient classical algorithms are known. We suggest a new
implementation of quantum computation with initially mixed states in which an
algorithm realization is achieved by means of optimal basis independent
transformations of qubits.Comment: 2 figures, 52 reference
Accounting for assay performance when estimating the temporal dynamics in SARS-CoV-2 seroprevalence in the U.S.
Reconstructing the incidence of SARS-CoV-2 infection is central to understanding the state of the pandemic. Seroprevalence studies are often used to assess cumulative infections as they can identify asymptomatic infection. Since July 2020, commercial laboratories have conducted nationwide serosurveys for the U.S. CDC. They employed three assays, with different sensitivities and specificities, potentially introducing biases in seroprevalence estimates. Using models, we show that accounting for assays explains some of the observed state-to-state variation in seroprevalence, and when integrating case and death surveillance data, we show that when using the Abbott assay, estimates of proportions infected can differ substantially from seroprevalence estimates. We also found that states with higher proportions infected (before or after vaccination) had lower vaccination coverages, a pattern corroborated using a separate dataset. Finally, to understand vaccination rates relative to the increase in cases, we estimated the proportions of the population that received a vaccine prior to infection
On opportunistic software reuse
The availability of open source assets for almost all imaginable domains has led the software industry toopportunistic design-an approach in which people develop new software systems in an ad hoc fashion by reusing and combining components that were not designed to be used together. In this paper we investigate this emerging approach. We demonstrate the approach with an industrial example in whichNode.jsmodules and various subsystems are used in an opportunistic way. Furthermore, to study opportunistic reuse as a phenomenon, we present the results of three contextual interviews and a survey with reuse practitioners to understand to what extent opportunistic reuse offers improvements over traditional systematic reuse approaches.Peer reviewe
Silencing Early Viral Replication in Macrophages and Dendritic Cells Effectively Suppresses Flavivirus Encephalitis
West Nile (WN) and St. Louis encephalitis (SLE) viruses can cause fatal
neurological infection and currently there is neither a specific treatment nor
an approved vaccine for these infections. In our earlier studies, we have
reported that siRNAs can be developed as broad-spectrum antivirals for the
treatment of infection caused by related viruses and that a small peptide called
RVG-9R can deliver siRNA to neuronal cells as well as macrophages. To increase
the repertoire of broad-spectrum antiflaviviral siRNAs, we screened 25 siRNAs
targeting conserved regions in the viral genome. Five siRNAs were found to
inhibit both WNV and SLE replication in vitro reflecting broad-spectrum
antiviral activity and one of these was also validated in vivo. In addition, we
also show that RVG-9R delivers siRNA to macrophages and dendritic cells,
resulting in effective suppression of virus replication. Mice were challenged
intraperitoneally (i.p.) with West Nile virus (WNV) and treated i.v. with
siRNA/peptide complex. The peritoneal macrophages isolated on day 3 post
infection were isolated and transferred to new hosts. Mice receiving macrophages
from the anti-viral siRNA treated mice failed to develop any disease while the
control mice transferred with irrelevant siRNA treated mice all died of
encephalitis. These studies suggest that early suppression of viral replication
in macrophages and dendritic cells by RVG-9R-mediated siRNA delivery is key to
preventing the development of a fatal neurological disease
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