24,585 research outputs found
Controlling Reversibility in Reversing Petri Nets with Application to Wireless Communications
Petri nets are a formalism for modelling and reasoning about the behaviour of
distributed systems. Recently, a reversible approach to Petri nets, Reversing
Petri Nets (RPN), has been proposed, allowing transitions to be reversed
spontaneously in or out of causal order. In this work we propose an approach
for controlling the reversal of actions of an RPN, by associating transitions
with conditions whose satisfaction/violation allows the execution of
transitions in the forward/reversed direction, respectively. We illustrate the
framework with a model of a novel, distributed algorithm for antenna selection
in distributed antenna arrays.Comment: RC 201
Event structure semantics of (controlled) reversible CCS
CCSK is a reversible form of CCS which is causal, meaning that ac- tions can be reversed if and only if each action caused by them has already been reversed; there is no control on whether or when a computation reverses. We pro- pose an event structure semantics for CCSK. For this purpose we define a cat- egory of reversible bundle event structures, and use the causal subcategory to model CCSK. We then modify CCSK to control the reversibility with a rollback primitive, which reverses a specific action and all actions caused by it. To define the event structure semantics of rollback, we change our reversible bundle event structures by making the conflict relation asymmetric rather than symmetric, and we exploit their capacity for non-causal reversibility
Constraints On The Topology Of The Universe From The WMAP First-Year Sky Maps
We compute the covariance expected between the spherical harmonic
coefficients of the cosmic microwave temperature anisotropy if the
universe had a compact topology. For fundamental cell size smaller than the
distance to the decoupling surface, off-diagonal components carry more
information than the diagonal components (the power spectrum). We use a maximum
likelihood analysis to compare the Wilkinson Microwave Anisotropy Probe
first-year data to models with a cubic topology. The data are compatible with
finite flat topologies with fundamental domain times the distance to
the decoupling surface at 95% confidence. The WMAP data show reduced power at
the quadrupole and octopole, but do not show the correlations expected for a
compact topology and are indistinguishable from infinite models.Comment: 16 pages, 5 figure
It\u27s A Wonderful World After All
https://digitalcommons.library.umaine.edu/mmb-vp/5029/thumbnail.jp
Gap probabilities in non-Hermitian random matrix theory
We compute the gap probability that a circle of
radius r around the origin contains exactly k complex eigenvalues. Four different ensembles of random matrices are considered: the Ginibre ensembles and their chiral complex counterparts, with both complex (beta=2) or quaternion real (beta=4) matrix elements. For general non-Gaussian weights we give a Fredholm determinant or Pfaffian representation respectively, depending on the non-Hermiticity parameter. At maximal non-Hermiticity, that is for rotationally invariant weights, the product of Fredholm eigenvalues for beta=4 follows from beta=2 by skipping every second factor, in contrast to the known relation for Hermitian ensembles. On additionally choosing Gaussian weights we give new explicit expressions for the Fredholm eigenvalues in the chiral case, in terms of Bessel-K and incomplete Bessel-I functions. This compares to known results for the Ginibre ensembles in terms of incomplete exponentials. Furthermore we present an asymptotic expansion of the logarithm of the gap probability for large argument r at large N in all four ensembles, up to including the third order linear term. We can provide strict upper and lower bounds and present numerical evidence for its conjectured values, depending on the number of exact zero eigenvalues in the chiral ensembles. For the Ginibre ensemble at beta=2 exact results were previously derived by Forrester
Impact of a new H/He equation of state on the evolution of massive brown dwarfs. New determination of the hydrogen burning limit
We have explored the impact of the latest equation of state (EOS) for dense
hydrogen-helium mixtures (Chabrier \& Debras 2021), which takes into account
the interactions between hydrogen and helium species, upon the evolution of
very low mass stars and brown dwarfs (BD). These interactions modify the
thermodynamic properties of the H/He mixture, notably the entropy, a quantity
of prime importance for these fully convective bodies, but also the onset and
the development of degeneracy throughout the body. This translates into a
faster cooling rate, i.e. cooler isentropes for a given mass and age, and thus
larger brown dwarf masses and smaller radii for given effective temperature and
luminosity than the models based on previous EOSs. This means that objects of a
given mass and age, in the range M\lesssim 0.1\,\msol, yr,
will have cooler effective temperatures and fainter luminosities. Confronting
these new models with several observationally determined BD dynamical masses,
we show that this improves the agreement between evolutionary models and
observations and resolves at least part of the observed discrepancies between
the properties of dynamical mass determinations and evolutionary models. A
noticeable consequence of this improvement of the dense H/He EOS is that it
yields a larger H-burning minimum mass, now found to be 0.075\,\msol
(78.5\,\mjup) with the ATMO atmosphere models for solar metallicity. These
updated brown dwarf models are made publicly available.Comment: To appear in Astronomy & Astrophysic
Reversing Single Sessions
Session-based communication has gained a widespread acceptance in practice as
a means for developing safe communicating systems via structured interactions.
In this paper, we investigate how these structured interactions are affected by
reversibility, which provides a computational model allowing executed
interactions to be undone. In particular, we provide a systematic study of the
integration of different notions of reversibility in both binary and multiparty
single sessions. The considered forms of reversibility are: one for completely
reversing a given session with one backward step, and another for also
restoring any intermediate state of the session with either one backward step
or multiple ones. We analyse the costs of reversing a session in all these
different settings. Our results show that extending binary single sessions to
multiparty ones does not affect the reversibility machinery and its costs
Sensitive PCR Method for Detection of Escherichia coli 0157:H7 and Other Shiga toxin-producing Bacteria in Ground Meat
Sensitivity of a polymerase chain reaction (PCR) procedure was evaluated for Escherichia coli O157:H7 and Shiga toxin gene (stx) detection in ground beef and ground pork at contamination levels of 0.14, 1.4, and 14 colony forming units per gram (CFU/g) of meat. The PCR procedure, developed during our previous research, amplifies three target genes simultaneously: uidA that is specific for E. coli O157:H7, and stx1 and stx2, the genes for Shiga toxins 1 and 2, respectively. Detection of the uidA gene by the PCR was 91% sensitive in beef and 55% sensitive in pork, and 90% and 71% sensitive for stx gene detection in beef and pork, respectively. In comparison, detection of E. coli O157:H7 by culture, done simultaneously with PCR, was 53% sensitive in beef and 11% sensitive in pork. Results indicate that this PCR procedure is a rapid and sensitive method for STEC and E. coli O157:H7 detection in meat at contamination levels less than 1 CFU/g
New England Regional Health Equity Profile & Call to Action
Good health is a foundation that allows people to participate in the most important aspects of life. The purpose of the New England Regional Health Equity Profile and Call to Action is to identify where differences in good health exist among racial, ethnic, and disability populations in New England as well as foster policy, programmatic, and individual action to combat health disparities and achieve health equity for racial, ethnic, disability and underserved populations in New England. The report was written by the members of the New England Regional Health Equity Council (RHEC), one of ten regional health equity councils formed by the Office of Minority Health at the federal Department of Health and Human Services. The mission of the New England RHEC is to achieve health equity for all through collective action in the New England region. The New England RHEC’s vision is to achieve health equity through cross-sector interaction and collaboration of activities and resources to optimize health for all where they live, learn, work, and play.
The New England Regional Health Equity Profile and Call to Action uses a “social determinants of health” approach. A social determinants of health approach focuses on understanding how the intersection of the social and physical environments; individual behaviors; and access to education, income, healthy foods and health care, impacts a wide range of health and quality-of-life outcomes. The report examines the following topics: Socio-Economic Status, Healthy Eating and Physical Activity, Risky Behaviors, Cultural Competency in Health Care, Health Care Access, Health Outcomes, and the Intersection of Race/Ethnicity & Disability. It also includes a description of State Health Equity Activities and a Regional Call to Action
- …