Lattice Boltzmann Simulations of Droplet formation in confined Channels with Thermocapillary flows

Based on mesoscale lattice Boltzmann simulations with the "Shan-Chen" model, we explore the influence of thermocapillarity on the break-up properties of fluid threads in a microfluidic T-junction, where a dispersed phase is injected perpendicularly into a main channel containing a continuous phase, and the latter induces periodic break-up of droplets due to the cross-flowing. Temperature effects are investigated by switching on/off both positive/negative temperature gradients along the main channel direction, thus promoting a different thread dynamics with anticipated/delayed break-up. Numerical simulations are performed at changing the flow-rates of both the continuous and dispersed phases, as well as the relative importance of viscous forces, surface tension forces and thermocapillary stresses. The range of parameters is broad enough to characterize the effects of thermocapillarity on different mechanisms of break-up in the confined T-junction, including the so-called "squeezing" and "dripping" regimes, previously identified in the literature. Some simple scaling arguments are proposed to rationalize the observed behaviour, and to provide quantitative guidelines on how to predict the droplet size after break-up.Comment: 18 pages, 9 figure

Approximate model-based shielding for safe reinforcement learning

Reinforcement learning (RL) has shown great potential for solving complex tasks in a variety of domains. However, applying RL to safety-critical systems in the real-world is not easy as many algorithms are sample-inefficient and maximising the standard RL objective comes with no guarantees on worst-case performance. In this paper we propose approximate model-based shielding (AMBS), a principled look-ahead shielding algorithm for verifying the performance of learned RL policies w.r.t. a set of given safety constraints. Our algorithm differs from other shielding approaches in that it does not require prior knowledge of the safety-relevant dynamics of the system. We provide a strong theoretical justification for AMBS and demonstrate superior performance to other safety-aware approaches on a set of Atari games with state-dependent safety-labels

Non-canonical binding site for bacterial initiation factor 3 on the large ribosomal subunit.

Canonical translation initiation in bacteria entails the assembly of the 30S initiation complex (IC), which binds the 50S subunit to form a 70S IC. IF3, a key initiation factor, is recruited to the 30S subunit at an early stage and is displaced from its primary binding site upon subunit joining. We employed four different FRET pairs to monitor IF3 relocation after 50S joining. IF3 moves away from the 30S subunit, IF1 and IF2, but can remain bound to the mature 70S IC. The secondary binding site is located on the 50S subunit in the vicinity of ribosomal protein L33. The interaction between IF3 and the 50S subunit is largely electrostatic with very high rates of IF3 binding and dissociation. The existence of the non-canonical binding site may help explain how IF3 participates in alternative initiation modes performed directly by the 70S ribosomes, such as initiation on leaderless mRNAs or re-initiation

Modeling instantaneous dynamic triggering in a 3–D fault system: application to the June 2000 South Iceland seismic sequence

We present a model of seismogenesis on an extended 3–D fault subjected to the external perturbations of coseismic stress changes due to an earthquake occurred on another fault (the causative fault). As an application, we consider the spatio–temporal stress distribution produced by the MS = 6.6 June 17, 2000 mainshock in the South Iceland Seismic Zone (SISZ) on the Hvalhnúkur fault. The latter is located nearly 64 km from the causative fault and failed 26 s after the mainshock with an estimated magnitude Mw  [5, 5.5], providing an example of instantaneous dynamic triggering. The stress perturbations are computed by means of a discrete wavenumber and reflectivity code. The response of the perturbed fault is then analyzed solving the truly 3–D, fully dynamic (or spontaneous) problem, accounting for crustal stratification. In a previous study, the response of the Hvalhnúkur fault was analyzed by using a spring–slider fault model, comparing the estimated perturbed failure time with the observed origin time. In addition to the perturbed failure time, the present model can provide numerical estimates of many other dynamical features of the triggered event that can be compared with available observations: the rupture history of the whole fault plane and its final extension and the seismic moment of the 26 s event. We show the key differences existing between a mass–spring model and the present extended fault model, in particular we show the essential role of the load exerted by the other slipping points of the fault. By considering both rate– and state–dependent laws and non–linear slip–dependent law, we show how the dynamics of the 26 s fault strongly depends on the assumed constitutive law and initial stress conditions. In the case of rate– and state– dependent governing laws, assuming an initial effective normal stress distribution which is suitable for the SISZ and consistent with previously stated conditions of instantaneous dynamic triggering of the Hvalhnúkur fault, we obtain results in general agreement with observations

805-1 Theophylline Reverses Myocardial Infarction-Related Brady and Tachy Arrhythmias: Role of Adenosine

Brady and tachyarrhythmias often complicate the early management of acute myocardial infarction (MI). Endogenously released adenosine (ADO) from ischemic cardiac cells has been proposed as a potential mediator of these arrhythmias. In order to test this hypothesis, theophylline (THEO), a competitive ADO receptor antagonist, was administered to nine patients who developed sustained or hemodynamically significant brady or tachyarrhythmias immediately following an acute inferior MI.MethodsOnce such an arrhythmia was detected, continuous ECG monitoring was begun. THEO was then administered i.v. at a rate of 100mg/min until the arrhythmia resolved or a maximum of 250mg THEO was infused. Patients were then monitored for 24 hours for recurrent arrhythmias.ResultsBradyarrhythmias were detected in 5 patients (3 with 3° AV block, 2 with 2° AV block). Tachyarrhythmias were detected in four patients (2 with atrial fibrillation, 2 with accelerated idioventricular rhythm). All patients converted to normal sinus rhythm within five minutes of the administration of THEO (178±57mg). No recurrent arrhythmia occurred in the follow-up period.ConclusionsMany of the brady and tachyarrhythmias which occur early after inferior MI are ADO-mediated. ADO receptor antagonism appears effective in converting these arrhythmias to normal sinus rhythm and may be considered as primary therapy

An observing system for the collection of fishery and oceanographic data

Fishery Observing System (FOS) was developed as a first and basic step towards fish stock abundance nowcasting/forecasting within the framework of the EU research program Mediterranean Forecasting System: Toward an Environmental Prediction (MFSTEP). The study of the relationship between abundance and environmental parameters also represents a crucial point towards forecasting. Eight fishing vessels were progressively equipped with FOS instrumentation to collect fishery and oceanographic data. The vessels belonged to different harbours of the Central and Northern Adriatic Sea. For this pilot application, anchovy (<I>Engraulis encrasicolus</I>, L.) was chosen as the target species. Geo-referenced catch data, associated with in-situ temperature and depth, were the FOS products but other parameters were associated with catch data as well. MFSTEP numerical circulation models provide many of these data. In particular, salinity was extracted from re-analysis data of numerical circulation models. Satellite-derived sea surface temperature (SST) and chlorophyll were also used as independent variables. Catch and effort data were used to estimate an abundance index (CPUE – Catch per Unit of Effort). Considering that catch records were gathered by different fishing vessels with different technical characteristics and operating on different fish densities, a standardized value of CPUE was calculated. A spatial and temporal average CPUE map was obtained together with a monthly mean time series in order to characterise the variability of anchovy abundance during the period of observation (October 2003–August 2005). In order to study the relationship between abundance and oceanographic parameters, Generalized Additive Models (GAM) were used. Preliminary results revealed a complex scenario: the southern sector of the domain is characterised by a stronger relationship than the central and northern sector where the interactions between the environment and the anchovy distribution are hidden by a higher percentage of variability within the system which is still unexplained. <br><br> GAM analysis showed that increasing the number of explanatory variables also increased the portion of variance explained by the model. Data exchange and interdisciplinary efforts will therefore be crucial for the success of this research activity

Evidences of instantaneous dynamic triggering during the seismic sequence of year 2000 in South Iceland

We analyze the coseismic stress perturbation during the June 17th, 2000 South Iceland seismic sequence; the mainshock (MS 6.6) was followed by three large events within few tens of seconds (8, 26, and 30 s, respectively) located within 80 km. The aim of this paper is to investigate short-term fault interaction and instantaneous triggering. This happens when a fault perturbed by a stress change fails before the end of the transient stress perturbation. We compute the shear, normal, and Coulomb stress changes as functions of time in a stratified elastic half-space by using discrete wavenumber and reflectivity methods. We calculate dynamic stresses caused by the mainshock at the hypocenters of these three subsequent events. Our numerical results show that the onset of the last two events is slightly delayed with respect to the arrival time of the second positive peak of Coulomb stress variation, while the first event occurred after the first positive stress peak. We have also analysed the response of a spring-slider system representing a fault governed by a rate- and state-dependent friction law, perturbed by shear and normal stress variations caused by the mainshock. The fault response to the computed stress perturbations is always clock advanced. We have found suitable constitutive parameters of the modelled fault that allow the instantaneous dynamic triggering of these three earthquakes. If the initial sliding velocity is comparable with the tectonic loading velocity, we obtained failure times close to the observed origin times for low values of the initial effective normal stress

Climacostol reduces tumour progression in a mouse model of melanoma via the p53-dependent intrinsic apoptotic programme

Climacostol, a compound produced by the ciliated protozoan Climacostomum virens, displayed cytotoxic properties in vitro. This study demonstrates that it has anti-tumour potential. Climacostol caused a reduction of viability/proliferation of B16-F10 mouse melanoma cells, a rapidly occurring DNA damage, and induced the intrinsic apoptotic pathway characterised by the dissipation of the mitochondrial membrane potential, the translocation of Bax to the mitochondria, the release of Cytochrome c from the mitochondria, and the activation of Caspase 9-dependent cleavage of Caspase 3. The apoptotic mechanism of climacostol was found to rely on the up-regulation of p53 and its targets Noxa and Puma. In vivo analysis of B16-F10 allografts revealed a persistent inhibition of tumour growth rate when melanomas were treated with intra-tumoural injections of climacostol. In addition, it significantly improved the survival of transplanted mice, decreased tumour weight, induced a remarkable reduction of viable cells inside the tumour, activated apoptosis and up-regulated the p53 signalling network. Importantly, climacostol toxicity was more selective against tumour than non-tumour cells. The anti-tumour properties of climacostol and the molecular events associated with its action indicate that it is a powerful agent that may be considered for the design of pro-apoptotic drugs for melanoma therapy

Interactions between Knowledge and Time in a First-Order Logic for Multi-Agent Systems: Completeness Results

We investigate a class of first-order temporal-epistemic logics for reasoning about multiagent systems. We encode typical properties of systems including perfect recall, synchronicity, no learning, and having a unique initial state in terms of variants of quantified interpreted systems, a first-order extension of interpreted systems. We identify several monodic fragments of first-order temporal-epistemic logic and show their completeness with respect to their corresponding classes of quantified interpreted systems. 1