The Pioneer anomaly in the context of the braneworld scenario

We examine the Pioneer anomaly - a reported anomalous acceleration affecting the Pioneer 10/11, Galileo and Ulysses spacecrafts - in the context of a braneworld scenario. We show that effects due to the radion field cannot account for the anomaly, but that a scalar field with an appropriate potential is able to explain the phenomena. Implications and features of our solution are analyzed.Comment: Final version to appear at Classical & Quantum Gravity. Plainlatex 19 page

Machine Learning Techniques for the Detection of Shockable Rhythms in Automated External Defibrillators

Early recognition of ventricular fibrillation (VF) and electrical therapy are key for the survivalof out-of-hospital cardiac arrest (OHCA) patients treated with automated external defibrilla-tors (AED). AED algorithms for VF-detection are customarily assessed using Holter record-ings from public electrocardiogram (ECG) databases, which may be different from the ECGseen during OHCA events. This study evaluates VF-detection using data from both OHCApatients and public Holter recordings. ECG-segments of 4-s and 8-s duration were ana-lyzed. For each segment 30 features were computed and fed to state of the art machinelearning (ML) algorithms. ML-algorithms with built-in feature selection capabilities wereused to determine the optimal feature subsets for both databases. Patient-wise bootstraptechniques were used to evaluate algorithm performance in terms of sensitivity (Se), speci-ficity (Sp) and balanced error rate (BER). Performance was significantly better for publicdata with a mean Se of 96.6%, Sp of 98.8% and BER 2.2% compared to a mean Se of94.7%, Sp of 96.5% and BER 4.4% for OHCA data. OHCA data required two times morefeatures than the data from public databases for an accurate detection (6 vs 3). No signifi-cant differences in performance were found for different segment lengths, the BER differ-ences were below 0.5-points in all cases. Our results show that VF-detection is morechallenging for OHCA data than for data from public databases, and that accurate VF-detection is possible with segments as short as 4-s

Trends in mortality from external causes in the Republic of Seychelles between 1989 and 2018.

Data on injury-related mortality are scarce in the African region. Mortality from external causes in the Seychelles was assessed, where all deaths are medically certified and the population is regularly enumerated. The four fields for underlying causes of death recorded were reviewed in the national vital statistics register. The age-standardised mortality rates were estimated (per 100,000 person-years) from external causes in 1989-1998, 1999-2008, and 2009-2018. Mortality rates per 100,000 person-years from external causes were 4-5 times higher among males than females, and decreased among males over the three 10-year periods (127.5, 101.4, 97.1) but not among females (26.9, 23.1, 26.9). The contribution of external causes to total mortality did not change markedly over time (males 11.6%, females 4.3% in 1989-2018). Apart from external deaths from undetermined causes (males 14.6, females 2.4) and "other unintentional injuries" (males 14.1, females 8.0), the leading external causes of death in 2009-2018 were drowning (25.9), road traffic injuries (18.0) and suicide (10.4) among males; and road traffic injuries (4.6), drowning (3.4) and poisoning (2.6) among females. Mortality from broad categories of external causes did not change consistently over time but rates of road traffic injuries increased among males. External causes contributed approximately 1 in 10 deaths among males and 1 in 20 among females, with no marked change in cause-specific rates over time, except for road traffic injuries. These findings emphasise the need for programs and policies in various sectors to address this large, but mostly avoidable health burden

Assessment of initial soil moisture conditions for event-based rainfall-runoff modelling

Flash floods are the most destructive natural hazards that occur in the Mediterranean region. Rainfall-runoff models can be very useful for flash flood forecasting and prediction. Event-based models are very popular for operational purposes, but there is a need to reduce the uncertainties related to the initial moisture conditions estimation prior to a flood event. This paper aims to compare several soil moisture indicators: local Time Domain Reflectometry (TDR) measurements of soil moisture, modelled soil moisture through the Interaction-Sol-Biosphere-Atmosphere (ISBA) component of the SIM model (Meteo-France), antecedent precipitation and base flow. A modelling approach based on the Soil Conservation Service-Curve Number method (SCS-CN) is used to simulate the flood events in a small headwater catchment in the Cevennes region (France). The model involves two parameters: one for the runoff production, S. and one for the routing component, K. The S parameter can be interpreted as the maximal water retention capacity, and acts as the initial condition of the model, depending on the antecedent moisture conditions. The model was calibrated from a 20-flood sample, and led to a median Nash value of 0.9. The local TDR measurements in the deepest layers of soil (80-140 cm) were found to be the best predictors for the S parameter. TDR measurements averaged over the whole soil profile, outputs of the SIM model, and the logarithm of base flow also proved to be good predictors, whereas antecedent precipitations were found to be less efficient. The good correlations observed between the TDR predictors and the S calibrated values indicate that monitoring soil moisture could help setting the initial conditions for simplified event-based models in small basins

Dissolution in a porous rock: effect on the concentration–discharge relationships

International audienceVarious empirical or physically-based theory have been proposed to understand how the solute concentration of a stream varies with the discharge. We focus here on the influence of the dynamics of the groundwater flow on the chemical erosion rate. To do so, we couple a one-dimensional aquifer model to a first order dissolution equation. If the aquifer extends far below the stream level, the theoretical discharge–concentration equation corresponds to the empirical " working model " proposed by Johnson in 1969, thus providing a physical interpretation of its parameters. Conversely, if the aquifer lays mainly above the stream level, a significantly different relationship is found. These theoretical findings are then compared to two field-data sets. From this comparison, we conclude that the dynamics of the groundwater flow could play a significant role in moderating the impact of dilution on the stream concentration at large discharges

Virtual sources and sinks during extracellular field shocks in cardiac cell cultures effects of source-sink interactions between adjacent tissue boundaries

Background— One mechanism by which extracellular field shocks (ECFSs) defibrillate the heart is by producing changes in membrane potential (V m ) at tissue discontinuities. Such virtual electrodes may produce new excitation waves or affect locally propagating action potentials. The rise time of V m determines the required duration of a single defibrillation pulse to reach a critical threshold for activation or for the modification of ion channel function, and depends on the electric and microstructural characteristics of the tissue. Methods and Results— We used optical mapping of V m in patterned cultures of neonatal rat ventricular myocytes to assess the relationship between cardiac structure and the early time course of V m during ECFSs. At monolayer boundaries, the time course of V m showed a close fit to the theoretical change predicted by theory, with a membrane time constant of 2.65±0.19 ms (n=13) and a length constant of 159±6 μm (n=10). Experiments in patterned strands, mimicking the resistive boundaries that occur naturally in the heart, explained the observation that the rate of rise and the maximal amplitudes of the V m changes are inversely related because of electrotonic interactions between structural boundaries. Interrupting ECFSs by very short intervals diminished V m , but did not cause major changes in its overall time course. Conclusions— Interaction between virtual sinks and sources decreases the magnitude of the changes in V m but accelerates its time course. For efficient defibrillation, short ECFSs are needed, with an amplitude adapted to match the boundary interaction. </jats:sec