Stochastic model for the alignment and tumbling of rigid fibres in two-dimensional turbulent shear flow

Non-spherical particles transported by an anisotropic turbulent flow preferentially align with the mean shear and intermittently tumble when the local strain fluctuates. Such an intricate behaviour is here studied for inertialess, rod-shaped particles embedded in a two-dimensional turbulent flow with homogeneous shear. A Lagrangian stochastic model for the rods angular dynamics is introduced and compared to the results of direct numerical simulations. The model consists in superposing a short-correlated random component to the steady large-scale mean shear, and can thereby be integrated analytically. To reproduce the single-time orientation statistics obtained numerically, it is found that one has to properly account for the combined effect of the mean shear, for anisotropic velocity gradient fluctuations, and for the presence of persistent rotating structures in the flow that bias Lagrangian statistics. The model is then used to address two-time statistics. The notion of tumbling rate is extended to diffusive dynamics by introducing the stationary probability flux of the rods unfolded angle. The model is found to reproduce the long-term effects of an average shear on the mean and the variance of the fibres angular increment. Still, it does not reproduce an intricate behaviour observed in numerics for intermediate times: the unfolded angle is there very similar to a L\'evy walk with distributions of increments displaying intermediate power-law tails

The examination and identification of bite marks in foods using 3D scanning and 3D comparison methods

Bite mark analysis offers the opportunity to identify the biter based on the individual characteristics of the dentitions. Normally, the main focus is on analysing bite mark injuries on human bodies, but also, bite marks in food may play an important role in the forensic investigation of a crime. This study presents a comparison of simulated bite marks in different kinds of food with the dentitions of the presumed biter. Bite marks were produced by six adults in slices of buttered bread, apples, different kinds of Swiss chocolate and Swiss cheese. The time-lapse influence of the bite mark in food, under room temperature conditions, was also examined. For the documentation of the bite marks and the dentitions of the biters, 3D optical surface scanning technology was used. The comparison was performed using two different software packages: the ATOS modelling and analysing software and the 3D studio max animation software. The ATOS software enables an automatic computation of the deviation between the two meshes. In the present study, the bite marks and the dentitions were compared, as well as the meshes of each bite mark which were recorded in the different stages of time lapse. In the 3D studio max software, the act of biting was animated to compare the dentitions with the bite mark. The examined food recorded the individual characteristics of the dentitions very well. In all cases, the biter could be identified, and the dentitions of the other presumed biters could be excluded. The influence of the time lapse on the food depends on the kind of food and is shown on the diagrams. However, the identification of the biter could still be performed after a period of time, based on the recorded individual characteristics of the dentition

A Lagrangian stochastic model for rod orientation in turbulent flows

International audienceSuspension of anisotropic particles can be found in various applications, e.g. industrial manufacturing processes or natural phenomena (micro-organism locomotion, ice crystal formation in clouds). Microscopic ellipsoidal bodies suspended in a turbulent fluid flow rotate in response to the velocity gradient of the flow. Understanding their orientation is important since it can affect the optical or rheological properties of the suspension (e.g. polymeric fluids). In this work, the orientation dynamics of rod-like tracer particles, i.e. long ellipsoidal particles (in the limit to infinity of the aspect-ratio) is studied. The size of the rod is assumed smaller than the Kolmogorov length scale but sufficiently large that its Brownian motion need not be considered. As a result, the local flow around a particle can be considered as inertia-free and Stokes flow solutions can be used to relate particle rotational dynamics to the local velocity gradient tensor A ij = ∂u i ∂x j. The orientation of a rod is described as the normalized solution of the linear ordinary differential equation for the separation vector R 12 between two fluid tracers. Separation evolves under the action of the velocity gradient tensor. Simultaneously, a re-normalization procedure R 12 R 12 is introduced to obtain the unit-vector p aligned with the rod. In this frame, the rod orientation is described by a Lagrangian stochastic model, assuming that cumulative effects of the velocity gradient tensor on the observation time interval fluctuate with a Gaussian distribution. Indeed, cumulative velocity gradient fluctuations are here represented by a white-noise tensor such that it preserves the incompressibility condition. Large observation timescale (overall objective of the work) justifies the Gaussian distribution hypotheses, with a decorrelation timescale equal to the Kolmogorov one τ η. Finally, the Lagrangian stochastic model is tested in the case of homogeneous isotropic turbulence

Testing and integrating the WLCG/EGEE middleware in the LHC computing

The main goal of the Experiment Integration and Support (EIS) team in WLCG is to help the LHC experiments with using proficiently the gLite middleware as part of their computing framework. This contribution gives an overview of the activities of the EIS team, and focuses on a few of them particularly important for the experiments. One activity is the evaluation of the gLite workload management system (WMS) to assess its adequacy for the needs of the LHC computing in terms of functionality, reliability and scalability. We describe in detail how the experiment requirements can be mapped to validation criteria, and the WMS performances are accurately measured under realistic load conditions over prolonged periods of time. Another activity is the integration of the Service Availability Monitoring system (SAM) with the experiment monitoring framework. The SAM system is widely used in the EGEE operations to identify malfunctions in Grid services, but it can be adapted to perform the same function on experiment-specific services. We describe how this has been done for some LHC experiments, which are now using SAM as part of their operations

A Random Shuffle Method to Expand a Narrow Dataset and Overcome the Associated Challenges in a Clinical Study: A Heart Failure Cohort Example

Heart failure (HF) affects at least 26 million people worldwide, so predicting adverse events in HF patients represents a major target of clinical data science. However, achieving large sample sizes sometimes represents a challenge due to difficulties in patient recruiting and long follow-up times, increasing the problem of missing data. To overcome the issue of a narrow dataset cardinality (in a clinical dataset, the cardinality is the number of patients in that dataset), population-enhancing algorithms are therefore crucial. The aim of this study was to design a random shuffle method to enhance the cardinality of an HF dataset while it is statistically legitimate, without the need of specific hypotheses and regression models. The cardinality enhancement was validated against an established random repeated-measures method with regard to the correctness in predicting clinical conditions and endpoints. In particular, machine learning and regression models were employed to highlight the benefits of the enhanced datasets. The proposed random shuffle method was able to enhance the HF dataset cardinality (711 patients before dataset preprocessing) circa 10 times and circa 21 times when followed by a random repeated-measures approach. We believe that the random shuffle method could be used in the cardiovascular field and in other data science problems when missing data and the narrow dataset cardinality represent an issue

Lymphedema and nutrition: A review

Nutrition is considered a basic component in the management of any vascular disease. Lymphedema is characterised by an increase of interstitial fluid due to a lymphatic system morphological and/or functional alteration. Therapeutic management of lymphedema includes a multi-faceted approach based on compression and physiotherapy mainly. Weight control and antiinflammatory and anti-edema diet are two additional necessary components of the holistic therapy in presence of primary or secondary limb lymphedema. This narrative review provides the available information derived from the scientific literature on nutrition in lymphedema, which anyway lacks robust evidence. Additional information and speculations are provided on the role of food, diet, nutraceuticals and fasting on the basic processes at the root of the chronic progressive degeneration of tissue lymph stasis, i.e. weight excess, inflammation, edema, fibroadiposis. More targeted and randomized studies are needed in order to assess and standardise the obvious, so far neglected, role of nutrition in lymphedema patients

Imaging performance above 150 keV of the wide field monitor on board the ASTENA concept mission

A new detection system for X-/Gamma-ray broad energy passband detectors for astronomy has been developed. This system is based on Silicon Drift Detectors (SDDs) coupled with scintillator bars; the SDDs act as a direct detector of soft (<30 keV) X-ray photons, while hard X-/Gamma-rays are stopped by the scintillator bars and the scintillation light is collected by the SDDs. With this configuration, it is possible to build compact, position sensitive detectors with unprecedented energy passband (2 keV - 10/20 MeV). The X and Gamma-ray Imaging Spectrometer (XGIS) on board the THESEUS mission, selected for Phase 0 study for M7, exploits this innovative detection system. The Wide Field Monitor - Imager and Spectrometer (WFM-IS) of the ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics) mission concept consists of 12 independent detection units, also based on this new technology. For the WFM-IS, a coded mask provides imaging capabilities up to 150 keV, while above this limit the instrument will act as a full sky spectrometer. However, it is possible to extend imaging capabilities above this limit by alternatively exploiting the Compton kinematics reconstruction or by using the information from the relative fluxes measured by the different cameras. In this work, we present the instrument design and results from MEGAlib simulations aimed at evaluating the effective area and the imaging performances of the WFM-IS above 150 keV

Ventilatory support and mechanical properties of the fibrotic lung acting as a "squishy ball"

Protective ventilation is the cornerstone of treatment of patients with the acute respiratory distress syndrome (ARDS); however, no studies have yet established the best ventilatory strategy to adopt when patients with acute exacerbation of interstitial lung disease (AE-ILD) are admitted to the intensive care unit. Due to the severe impairment of the respiratory mechanics, the fibrotic lung is at high risk of developing ventilator-induced lung injury, regardless of the lung fibrosis etiology. The purpose of this review is to analyze the effects of mechanical ventilation in AE-ILD and to increase the knowledge on the characteristics of fibrotic lung during artificial ventilation, introducing the concept of "squishy ball lung". The role of positive end-expiratory pressure is discussed, proposing a "lung resting strategy" as opposed to the "open lung approach". The review also discusses the practical management of AE-ILD patients discussing illustrative clinical cases

A FPGA-based digital readout system for a multi-channel X and gamma-ray spectrometer

The XGS project aims to develop a multi-channel broadband X and gamma -ray spectrometer for space applications. The experiment envisages the use of solid-state Silicon Drift Detectors coupled to inorganic scintillator bars. A prototype is under development in the framework of an INAF funded project, in which the detector signal will be digitized by a fast ADC and further digitally processed. An overview of the system architecture and the test equipment currently under development based on low-cost commercial system-on-chip FPGA boards will be given