Behavioural Types for Local-First Software

Peer-to-peer systems are the most resilient form of distributed computing, but the design of robust protocols for their coordination is difficult. This makes it hard to specify and reason about global behaviour of such systems. This paper presents swarm protocols to specify such systems from a global viewpoint. Swarm protocols are projected to machines, that is local specifications of peers. We take inspiration from behavioural types with a key difference: peers communicate through an event notification mechanism rather than through point-to-point message passing. Our goal is to adhere to the principles of local-first software where network devices collaborate on a common task while retaining full autonomy: every participating device can locally make progress at all times, not encumbered by unavailability of other devices or network connections. This coordination-free approach leads to inconsistencies that may emerge during computations. Our main result shows that under suitable well-formedness conditions for swarm protocols consistency is eventually recovered and the locally observable behaviour of conforming machines will eventually match the global specification. Our model elaborates on the Actyx industrial platform and provides the basis for tool support: we sketch an implemented prototype which proves this work a viable step towards reasoning about local-first and peer-to-peer software systems

Behavioural Types for Local-First Software (Artifact)

This artifact supports the theory of swarm protocols presented in the related article. Specifically, following the top-down development typical of choreographic approaches, our artifact enables the specification of systems of peers communicating through an event notification mechanism from a global viewpoint which can then be projected to local specifications of peers, rendered as machines. To the best of our knowledge, ours is the first implementation of a behavioural type framework supporting the application of the principles of local-first software for network devices which collaborate on a common task while retaining full autonomy. The artifact can be integrated in the Actyx industrial platform; this proves this work a viable step towards reasoning about local-first and peer-to-peer software systems

Reproductive Physiology of Aedes (Aedimorphus) vexans (Diptera: Culicidae) in Relation to Flight Potential

Total protein, lipid, and glycogen of Aedes vexans (Meigen) were related linearly to body size at eclosion. Starvation after emergence led to the determination of minimal irreducible amounts of protein, lipid, and glycogen and the availability of the teneral reserves, whereas access to sucrose revealed the potential for reserve synthesis. Glycogenesis and lipogenesis increased reserves ≈10-fold the teneral value within 1 and 2 wk after emergence, respectively. Carbohydrate feeding was an essential behavior before blood feeding and oogenesis commenced. Female flight was tested on a flight mill. Maximal flights of 10-17 km in a single night occurred at 2 wk posteclosion and paralleled maximal reserve syntheses. Comparisons of our laboratory data to host-seeking mosquitoes in the field confirmed our data. The vast majority of maternal lipid was transferred to the yolk when a blood meal was taken, but only a quarter of the blood protein was recovered from mature ovaries. Maternal glycogen was used mainly for flight. Fecundity varied between 20 and 120 eggs per female and was determined largely by body size and blood meal volume. At 27°C, maximal egg numbers were produced, but at 22 and 17°C the caloric yolk content was greater. Females from the southern United States were smaller than females from northern areas. However, southern females had similar fecundity as northern females, and their flight performances were similar. Differences in the reproductive physiology between this species and Ae. aegypti were discusse

Stability Verification of Neural Network Controllers using Mixed-Integer Programming

We propose a framework for the stability verification of Mixed-Integer Linear Programming (MILP) representable control policies. This framework compares a fixed candidate policy, which admits an efficient parameterization and can be evaluated at a low computational cost, against a fixed baseline policy, which is known to be stable but expensive to evaluate. We provide sufficient conditions for the closed-loop stability of the candidate policy in terms of the worst-case approximation error with respect to the baseline policy, and we show that these conditions can be checked by solving a Mixed-Integer Quadratic Program (MIQP). Additionally, we demonstrate that an outer and inner approximation of the stability region of the candidate policy can be computed by solving an MILP. The proposed framework is sufficiently general to accommodate a broad range of candidate policies including ReLU Neural Networks (NNs), optimal solution maps of parametric quadratic programs, and Model Predictive Control (MPC) policies. We also present an open-source toolbox in Python based on the proposed framework, which allows for the easy verification of custom NN architectures and MPC formulations. We showcase the flexibility and reliability of our framework in the context of a DC-DC power converter case study and investigate its computational complexity

A Measurement of Spin Asymmetries in Quasi-Real Photo-Production of Hadrons with High Transverse Momentum at COMPASS

During 2002–2004, the COMPASS experiment at the CERN SPS has recorded 1.5 fb−1 of deep inelastic scattering events with polarized muon beam and polarized deuterium target. The cross section for singleinclusive charged hadron production in dependence on the hadron’s transverse momentum pT is extracted. A PYTHIA and GEANT simulation is used to obtain the acceptance correction factors. The double spin asymmetry $A^{hd}_{LL}$ is measured in the region 1 GeV/c < pT < 3:5 GeV/c, the pT dependence of which is connected to the gluon polarization \DeltaG

The significance of detailed structure in the boundary layer to thermal radiation at the surface in climate models

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95310/1/grl7683.pd

C60+_{60}^+ and the Diffuse Interstellar Bands: An Independent Laboratory Check

In 2015, Campbell et al. (Nature 523, 322) presented spectroscopic laboratory gas phase data for the fullerene cation, C$_{60}^+$, that coincide with reported astronomical spectra of two diffuse interstellar band (DIB) features at 9633 and 9578 \AA. In the following year additional laboratory spectra were linked to three other and weaker DIBs at 9428, 9366, and 9349 \AA. The laboratory data were obtained using wavelength-dependent photodissociation spectroscopy of small (up to three) He-tagged C$_{60}^+-$He$_n$ ion complexes, yielding rest wavelengths for the bare C$_{60}^+$ cation by correcting for the He-induced wavelength shifts. Here we present an alternative approach to derive the rest wavelengths of the four most prominent C$_{60}^+$ absorption features, using high resolution laser dissociation spectroscopy of C$_{60}^+$ embedded in ultracold He droplets. Accurate wavelengths of the bare fullerene cation are derived based on linear wavelength shifts recorded for He$_n$C$_{60}^+$ species with $n$ up to 32. A careful analysis of all available data results in precise rest wavelengths (in air) for the four most prominent C$_{60}^+$ bands: 9631.9(1) \AA, 9576.7(1) \AA, 9427.5(1) \AA, and 9364.9(1) \AA. The corresponding band widths have been derived and the relative band intensity ratios are discussed

PDE7A1 hydrolyzes cCMP

AbstractThe degradation and biological role of the cyclic pyrimidine nucleotide cCMP is largely elusive. We investigated nucleoside 3′,5′-cyclic monophosphate (cNMP) specificity of six different recombinant phosphodiesterases (PDEs) by using a highly-sensitive HPLC–MS/MS detection method. PDE7A1 was the only enzyme that hydrolyzed significant amounts of cCMP. Enzyme kinetic studies using purified GST-tagged truncated PDE7A1 revealed a cCMP KM value of 135±19μM. The Vmax for cCMP hydrolysis reached 745±27nmol/(minmg), which is about 6-fold higher than the corresponding velocity for adenosine 3′,5′-cyclic monophosphate (cAMP) degradation. In summary, PDE7A is a high-speed and low-affinity PDE for cCMP

Comparing Two Subjective Rating Scales Assessing Cognitive Load During Technology-Enhanced STEM Laboratory Courses

Cognitive load theory is considered universally applicable to all kinds of learning scenarios. However, instead of a universal method for measuring cognitive load that suits different learning contexts or target groups, there is a great variety of assessment approaches. Particularly common are subjective rating scales, which even allow for measuring the three assumed types of cognitive load in a differentiated way. Although these scales have been proven to be effective for various learning tasks, they might not be an optimal fit for the learning demands of specific complex environments such as technology-enhanced STEM laboratory courses. The aim of this research was therefore to examine and compare the existing rating scales in terms of validity for this learning context and to identify options for adaptation, if necessary. For the present study, the two most common subjective rating scales that are known to differentiate between load types (the cognitive load scale by Leppink et al. and the naïve rating scale by Klepsch et al.) were slightly adapted to the context of learning through structured hands-on experimentation where elements such as measurement data, experimental setups, and experimental tasks affect knowledge acquisition. N 95 engineering students performed six experiments examining basic electric circuits where they had to explore fundamental relationships between physical quantities based on the observed data. Immediately after the experimentation, the students answered both adapted scales. Various indicators of validity, which considered the scales’ internal structure and their relation to variables such as group allocation as participants were randomly assigned to two conditions with a contrasting spatial arrangement of the measurement data, were analyzed. For the given dataset, the intended three-factorial structure could not be confirmed, and most of the a priori-defined subscales showed insufficient internal consistency. A multitrait–multimethod analysis suggests convergent and discriminant evidence between the scales which could not be confirmed sufficiently. The two contrasted experimental conditions were expected to result in different ratings for the extraneous load, which was solely detected by one adapted scale. As a further step, two new scales were assembled based on the overall item pool and the given dataset. They revealed a three-factorial structure in accordance with the three types of load and seemed to be promising new tools, although their subscales for extraneous load still suffer from low reliability scores