533 research outputs found
Session Coalgebras: A Coalgebraic View on Session Types and Communication Protocols
Compositional methods are central to the development and verification of
software systems. They allow to break down large systems into smaller
components, while enabling reasoning about the behaviour of the composed
system. For concurrent and communicating systems, compositional techniques
based on behavioural type systems have received much attention. By abstracting
communication protocols as types, these type systems can statically check that
programs interact with channels according to a certain protocol, whether the
intended messages are exchanged in a certain order. In this paper, we put on
our coalgebraic spectacles to investigate session types, a widely studied class
of behavioural type systems. We provide a syntax-free description of
session-based concurrency as states of coalgebras. As a result, we rediscover
type equivalence, duality, and subtyping relations in terms of canonical
coinductive presentations. In turn, this coinductive presentation makes it
possible to elegantly derive a decidable type system with subtyping for
-calculus processes, in which the states of a coalgebra will serve as
channel protocols. Going full circle, we exhibit a coalgebra structure on an
existing session type system, and show that the relations and type system
resulting from our coalgebraic perspective agree with the existing ones.Comment: 36 pages, submitte
Session Coalgebras: A Coalgebraic View on Regular and Context-Free Session Types
Compositional methods are central to the verification of software systems. For concurrent and communicating systems, compositional techniques based on behavioural type systems have received much attention. By abstracting communication protocols as types, these type systems can statically check that channels in a program interact following a certain protocolâwhether messages are exchanged in the intended order. In this article, we put on our coalgebraic spectacles to investigate session types, a widely studied class of behavioural type systems. We provide a syntax-free description of session-based concurrency as states of coalgebras. As a result, we rediscover type equivalence, duality, and subtyping relations in terms of canonical coinductive presentations. In turn, this coinductive presentation enables us to derive a decidable type system with subtyping for the Ï-calculus, in which the states of a coalgebra will serve as channel protocols. Going full circle, we exhibit a coalgebra structure on an existing session type system, and show that the relations and type system resulting from our coalgebraic perspective coincide with existing ones. We further apply to session coalgebras the coalgebraic approach to regular languages via the so-called rational fixed point, inspired by the trinity of automata, regular languages, and regular expressions with session coalgebras, rational fixed point, and session types, respectively. We establish a suitable restriction on session coalgebras that determines a similar trinity, and reveals the mismatch between usual session types and our syntax-free coalgebraic approach. Furthermore, we extend our coalgebraic approach to account for context-free session types, by equipping session coalgebras with a stack
Quality indicators for patients with traumatic brain injury in European intensive care units
Background: The aim of this study is to validate a previously published consensus-based quality indicator set for the management of patients with traumatic brain injury (TBI) at intensive care units (ICUs) in Europe and to study its potential for quality measur
ARDD 2020: from aging mechanisms to interventions
Aging is emerging as a druggable target with growing interest from academia, industry and investors. New technologies such as artificial intelligence and advanced screening techniques, as well as a strong influence from the industry sector may lead to novel discoveries to treat age-related diseases. The present review summarizes presentations from the 7th Annual Aging Research and Drug Discovery (ARDD) meeting, held online on the 1st to 4th of September 2020. The meeting covered topics related to new methodologies to study aging, knowledge about basic mechanisms of longevity, latest interventional strategies to target the aging process as well as discussions about the impact of aging research on society and economy. More than 2000 participants and 65 speakers joined the meeting and we already look forward to an even larger meeting next year. Please mark your calendars for the 8th ARDD meeting that is scheduled for the 31st of August to 3rd of September, 2021, at Columbia University, USA
Search for the doubly charmed baryon Î cc + in the Î c + Ï â Ï + final state
Abstract: A search for the doubly charmed baryon Îcc+ is performed in the Îc+ÏâÏ+ invariant-mass spectrum, where the Îc+ baryon is reconstructed in the pKâÏ+ final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fbâ1. No significant signal is observed in the invariant-mass range of 3.4â3.8 GeV/c2. Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the Îcc++â (Îc+â pKâÏ+)Ï+ decay for different Îcc+ mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the Îcc+âÎc+KâÏ+ decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c2, including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5â3.7 GeV/c2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties
Evidence of a J/psi Lambda structure and observation of excited Xi(-) states in the Xi(-)(b) -> J/psi Lambda K- decay
First evidence of a structure in the invariant mass
distribution is obtained from an amplitude analysis of decays. The observed structure is consistent with being due to
a charmonium pentaquark with strangeness. Its mass and width are determined to
be 4458.8\pm2.9\,^{+4.7}_{-1.1}MeV and 17.3\pm6.5\,^{+8.0}_{-5.7}MeV, where
the quoted uncertainties are statistical and systematic, respectively. The
structure is also consistent with being due to two resonances. In addition, the
narrow excited states, and , are
seen for the first time in a decay, and their masses and widths
are measured with improved precision. The analysis is performed using
collision data corresponding to a total integrated luminosity of 9fb,
collected with the LHCb experiment at centre-of-mass energies of , and
TeV.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-039.html (LHCb
public pages
Searches for rare B-s(0) and B-0 decays into four muons
Searches for rare and decays into four muons are performed
using proton-proton collision data recorded by the LHCb experiment,
corresponding to an integrated luminosity of 9 . Direct decays
and decays via light scalar and resonances are considered. No evidence
for the six decays searched for is found and upper limits at the 95% confidence
level on their branching fractions ranging between and
are set
Session Coalgebras: A Coalgebraic View on Session Types and Communication Protocols
Compositional methods are central to the development and verification of software systems. They allow breaking down large systems into smaller components, while enabling reasoning about the behaviour of the composed system. For concurrent and communicating systems, compositional techniques based on behavioural type systems have received much attention. By abstracting communication protocols as types, these type systems can statically check that programs interact with channels according to a certain protocol, whether the intended messages are exchanged in a certain order. In this paper, we put on our coalgebraic spectacles to investigate session types, a widely studied class of behavioural type systems. We provide a syntax-free description of session-based concurrency as states of coalgebras. As a result, we rediscover type equivalence, duality, and subtyping relations in terms of canonical coinductive presentations. In turn, this coinductive presentation makes it possible to elegantly derive a decidable type system with subtyping for í-calculus processes, in which the states of a coalgebra will serve as channel protocols. Going full circle, we exhibit a coalgebra structure on an existing session type system, and show that the relations and type system resulting from our coalgebraic perspective agree with the existing ones
12 Grand Challenges in Single-Cell Data Science
Laehnemann D, Köster J, Szczurek E, et al. 12 Grand Challenges in Single-Cell Data Science. PeerJ. 2019.The recent upswing of microfluidics and combinatorial indexing strategies, further enhanced by very low sequencing costs, have turned single cell sequencing into an empowering technology; analyzing thousandsâor even millionsâof cells per experimental run is becoming a routine assignment in laboratories worldwide. As a consequence, we are witnessing a data revolution in single cell biology. Although some issues are similar in spirit to those experienced in bulk sequencing, many of the emerging data science problems are unique to single cell analysis; together, they give rise to the new realm of 'Single-Cell Data Science'.
Here, we outline twelve challenges that will be central in bringing this new field forward. For each challenge, the current state of the art in terms of prior work is reviewed, and open problems are formulated, with an emphasis on the research goals that motivate them.
This compendium is meant to serve as a guideline for established researchers, newcomers and students alike, highlighting interesting and rewarding problems in 'Single-Cell Data Science' for the coming years.</jats:p
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