502 research outputs found
CoCaml: Functional Programming with Regular Coinductive Types
Functional languages offer a high level of abstraction, which results in programs that are elegant and easy to understand. Central to the development of functional programming are inductive and coinductive types and associated programming constructs, such as pattern-matching. Whereas inductive types have a long tradition and are well supported in most languages, coinductive types are subject of more recent research and are less mainstream.
We present CoCaml, a functional programming language extending OCaml, which allows us to define recursive functions on regular coinductive datatypes. These functions are defined like usual recursive functions, but parameterized by an equation solver. We present a full implementation of all the constructs and solvers and show how these can be used in a variety of examples, including operations on infinite lists, infinitary γ-terms, and p-adic numbers
LISA ON TABLE: AN OPTICAL SIMULATOR FOR LISA
LISA, the first space project for detecting gravitational waves, relies on two main technical challenges: the free falling masses and an outstanding precision on phase shift measurements (a few pm on 5 Mkm in the LISA band). The technology of the free falling masses, i.e. their isolation to forces other than gravity and the capability for the spacecraft to precisely follow the test masses, will soon be tested with the technological LISA Pathfinder mission. The performance of the phase measurement will be achieved by at least two stabilization stages: a pre-stabilisation of the laser frequency at a level of 10-13 (relative frequency stability) will be further improved by using numerical algorithms, such as Time Delay Interferometry, which have been theoretically and numerically demonstrated to reach the required performance level (10-21). Nevertheless, these algorithms, though already tested with numerical model of LISA, require experimental validation, including 'realistic' hardware elements. Such an experiment would allow to evaluate the expected noise level and the possible interactions between subsystems. To this end, the APC is currently developing an optical benchtop experiment, called LISA On Table (LOT), which is representative of the three LISA spacecraft. A first module of the LOT experiment has been mounted and is being characterized. After completion this facility may be used by the LISA community to test hardware (photodiodes, phasemeters) or software (reconstruction algorithms) components
Switzerland: National Trends in Sexual Behaviour in the Context of HIV/STI Behavioural Surveillance 1987–2012
Background: National trends in sexual behaviour have been assessed mainly in the context of the HIV related behavioural surveillance system set up in Switzerland between 1987 and 1992.
Methods: Several populations are included in the system. Repeatedsurveys have been regularly conducted among the general population and youth, men having sex with other men (MSM), injecting drug users (IDU). Data on sexual behaviour are regularly recorded among people living with HIV/Aids (PLWHA) included in the Swiss HIV Cohort
Tissue Engineering for Periodontal Ligament Regeneration: Biomechanical Specifications
The periodontal biomechanical environment is very difficult to investigate.
By the complex geometry and composition of the periodontal ligament, its
mechanical behavior is very dependent on the type of loading (compressive vs.
tensile loading; static vs. cyclic loading; uniaxial vs. multiaxial) and the
location around the root (cervical, middle, or apical). These different aspects
of the periodontal ligament make it difficult to develop a functional
biomaterial to treat periodontal attachment due to periodontal diseases. This
review aims to describe the structural and biomechanical properties of the
periodontal ligament. Particular importance is placed in the close
interrelationship that exists between structure and biomechanics: the
periodontal ligament structural organization is specific to its biomechanical
environment, and its biomechanical properties are specific to its structural
arrangement. This balance between structure and biomechanics can be explained
by a mechanosensitive periodontal cellular activity. These specifications have
to be considered in the further tissue engineering strategies for the
development of an efficient biomaterial for periodontal tissues regeneration
Reluplex: An Efficient SMT Solver for Verifying Deep Neural Networks
Deep neural networks have emerged as a widely used and effective means for
tackling complex, real-world problems. However, a major obstacle in applying
them to safety-critical systems is the great difficulty in providing formal
guarantees about their behavior. We present a novel, scalable, and efficient
technique for verifying properties of deep neural networks (or providing
counter-examples). The technique is based on the simplex method, extended to
handle the non-convex Rectified Linear Unit (ReLU) activation function, which
is a crucial ingredient in many modern neural networks. The verification
procedure tackles neural networks as a whole, without making any simplifying
assumptions. We evaluated our technique on a prototype deep neural network
implementation of the next-generation airborne collision avoidance system for
unmanned aircraft (ACAS Xu). Results show that our technique can successfully
prove properties of networks that are an order of magnitude larger than the
largest networks verified using existing methods.Comment: This is the extended version of a paper with the same title that
appeared at CAV 201
Comparison of plant location determinants: Food versus non-food agricultural processors
The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311
Towards Physical Hybrid Systems
Some hybrid systems models are unsafe for mathematically correct but
physically unrealistic reasons. For example, mathematical models can classify a
system as being unsafe on a set that is too small to have physical importance.
In particular, differences in measure zero sets in models of cyber-physical
systems (CPS) have significant mathematical impact on the mathematical safety
of these models even though differences on measure zero sets have no tangible
physical effect in a real system. We develop the concept of "physical hybrid
systems" (PHS) to help reunite mathematical models with physical reality. We
modify a hybrid systems logic (differential temporal dynamic logic) by adding a
first-class operator to elide distinctions on measure zero sets of time within
CPS models. This approach facilitates modeling since it admits the verification
of a wider class of models, including some physically realistic models that
would otherwise be classified as mathematically unsafe. We also develop a proof
calculus to help with the verification of PHS.Comment: CADE 201
Mapping HIV-related behavioural surveillance among injecting drug users in Europe, 2008.
The systematic collection of behavioural information is an important component of second-generation HIV surveillance. The extent of behavioural surveillance among injecting drug users (IDUs) in Europe was examined using data collected through a questionnaire sent to all 31 countries of the European Union and European Free Trade Association as part of a European-wide behavioural surveillance mapping study on HIV and other sexually transmitted infections. The questionnaire was returned by 28 countries during August to September 2008: 16 reported behavioural surveillance studies (two provided no further details). A total of 12 countries used repeated surveys for behavioural surveillance and five used their Treatment Demand Indicator system (three used both approaches). The data collected focused on drug use, injecting practices, testing for HIV and hepatitis C virus and access to healthcare. Eight countries had set national indicators: three indicators were each reported by five countries: the sharing any injecting equipment, uptake of HIV testing and uptake of hepatitis C virus testing. The recall periods used varied. Seven countries reported conducting one-off behavioural surveys (in one country without a repeated survey, these resulted an informal surveillance structure). All countries used convenience sampling, with service-based recruitment being the most common approach. Four countries had used respondent-driven sampling. Three fifths of the countries responding (18/28) reported behavioural surveillance activities among IDUs; however, harmonisation of behavioural surveillance indicators is needed
P16-45. High avidity CD4+ T cell response directed to an immunodominant Gag epitope in HIV controllers: an ANRS EP36 study
International audiencen.
Rain attenuation prediction model for satellite communications based on the Météo-France ensemble prediction system PEARP
This paper presents an
example of the usage of ensemble weather forecasting for the control of
satellite-based communication systems. Satellite communication systems become
increasingly sensitive to weather conditions as their operating frequency
increases to avoid electromagnetic spectrum congestion and enhance their
capacity. In the microwave domain, electromagnetic waves that are conveying
information are attenuated between the satellite and Earth terminals in the
presence of hydrometeors (mostly rain drops and more marginally cloud
droplets). To maintain a reasonable level of service availability, even with
adverse weather conditions considering the scarcity of amplification power in
spacecraft, fade mitigation techniques have been developed. The general idea
behind those fade mitigation techniques is to reroute, change the
characteristics or reschedule the transmission in the case of too-significant
propagation impairments. For some systems, a scheduling on how to use those
mechanisms some hours in advance is required, making assumptions on the
future weather conditions affecting the link. To this aim the use of weather
forecast data to control the attenuation compensation mechanisms seems of
particular interest to maximize the performances of the communication links
and hence of the associated economic value. A model to forecast the
attenuation on the link based on forecasted rainfall amounts from
deterministic or ensemble weather forecasting is presented and validated. In
a second phase, the model's application to a simplified telecommunication
system allows us to demonstrate the valuable contribution of weather
forecasting in the system's availability optimization or in the system's
throughput optimization. The benefit of using ensemble forecasts rather than
deterministic ones is demonstrated as well.</p
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