A phenomenological model for predicting the early development of the flame kernel in spark-ignition engines

This work presents a simple and effective phenomenological model for the prediction of the early growth of the flame kernel in SI engines, including its initiation as a result of the electrical breakdown of the fuel/air mixture between the spark plug electrodes. The present model aims to provide an improved description of the ignition-affected early phases of flame kernel development compared to the majority of models currently available in literature. In particular, these models focus on electrical energy supply and turbulence, whereas the stretch-induced kernel growth slowdown is quantified with linear models that are inconsistent with the small kernel radius. For the flame kernel initiation, this model replaces the current methods that rely on 1D heat diffusion within a plasma column with a more consistent analysis of post-breakdown conditions. Concerning the kernel growth, the present model couples the mass and energy conservation equations of a spherical kernel with the species and temperature profiles outside of it. This combination leads to a non-linear description of the flame stretch, according to which the kernel development is controlled by the Lewis-number-dependent balance between the heat gained via combustion and the heat lost via thermal diffusion. As a result, the kernel temperature differs from the adiabatic flame temperature, causing the laminar flame speed to change from its adiabatic value and ultimately affecting the overall kernel development. Kernel growth predictions are conducted for laminar flames and compared to literature data, showing a satisfactory agreement and highlighting the ability to describe the stretch-induced kernel slowdown, up to its possible extinction. A good agreement with literature data is also obtained for kernel expansions under moderately turbulent conditions, typical of internal combustion engines. The simple formulation of the present model enables swift integration into phenomenological combustion models for spark-ignition engines, while simultaneously offering useful insight into the early kernel development even for CFD-based approaches

Sulle orme del consumatore affinity analysis e knowledge visualization per il processo decisionale

L\u2019articolo analizza i reali comportamenti di acquisto dell\u2019acquirente all\u2019interno del punto vendita e individua i pattern latenti pi\uf9 significativi attraverso un\u2019analisi di affinit\ue0 di 128.364 scontrini estratti da un dataset di 715.662 transazioni effettuate in un anno. Lo studio individua le strutture associative pi\uf9 ricorrenti relativamente alla singola merceologia. Attraverso la tecnica della Market Basket Analysis \ue8 stato possibile individuare le categorie merceologiche che creano \u201cpoli d\u2019attrazione\u201d sul punto vendita stimolando acquisti di altre categorie. In particolar modo, applicando le regole associative sul punto vendita \ue8 stato possibile identificare le \u201caree calde\u201d e le \u201caree fredde\u201d. L\u2019articolo evidenzia quindi alcune riflessioni sulle strategie che possono adottare gli store manager

The three-body recombination of a condensed Bose gas near a Feshbach resonance

In this paper, we study the three-body recombination rate of a homogeneous dilute Bose gas with a Feshbach resonance at zero temperature. The ground state and excitations of this system are obtained. The three-body recombination in the ground state is due to the break-up of an atom pair in the quantum depletion and the formation of a molecule by an atom from the broken pair and an atom from the condensate. The rate of this process is in good agreement with the experiment on $^{23}$Na in a wide range of magnetic fields.Comment: 10 pages, 2 figures, to be published in Phys. Rev.

Experience with the Platelia Candida ELISA for the diagnosis of invasive candidosis in neonatal patients

ABSTRACTThis preliminary study evaluated the use of the Platelia Candida antigen kit for the diagnosis of invasive candidosis in 70 of 184 pre-term infants admitted to a neonatal intensive care unit between March 2004 and March 2006. The frequency of confirmed candidaemia was 6.5%. The sensitivity and specificity of the assay were 94.4% and 94.2%, respectively, with a positive predictive value of 85% and a negative predictive value of 98%. These results suggest that the inclusion of regular serological surveillance for mannanaemia in some pre-term infants would complement blood cultures for the early detection of candidosis

The effect of different medium compositions and LAB strains on fermentation Volatile Organic Compounds (VOCs) analysed by Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS)

Lactic acid bacteria (LAB) fermentation is a viable approach for producing plant-based flavour compounds; however, little is understood about the impact of different LAB strains and medium compositions on the production of volatile organic compounds (VOCs). This study investigated the impact of the addition of individual amino acids (AAs) (L-leucine, L-isoleucine, L-phenylalanine, L-glutamic acid, L-aspartic acid, L-threonine, or L-methionine) to a defined medium (DM) on the generation of VOCs (after 0, 7, and 14 days) by one of three LAB strains (Levilactobacillus brevis WLP672 (LB672), Lactiplantibacillus plantarum LP100 (LP100), and Pediococcus pentosaceus PP100 (PP100)), using proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS). The concentration of m/z 45.031 (t.i. acetaldehyde) was significantly (p < 0.05) higher after 7 days of fermentation by LP100 in the DM supplemented with threonine compared to all other media fermented by all three strains. The concentrations of m/z 49.012 (t.i. methanethiol) and m/z 95.000 (t.i. dimethyl disulfide) were significantly (p < 0.05) higher after 7 days of fermentation by either LP100, PP100, or LB672 in the DM supplemented with methionine compared to all other media. Information on the role of individual AAs on VOCs generation by different LAB strains will help to guide flavour development from the fermentation of plant-based substrate

Emotionotopy in the human right temporo-parietal cortex

AbstractHumans use emotions to decipher complex cascades of internal events. However, which mechanisms link descriptions of affective states to brain activity is unclear, with evidence supporting either local or distributed processing. A biologically favorable alternative is provided by the notion of gradient, which postulates the isomorphism between functional representations of stimulus features and cortical distance. Here, we use fMRI activity evoked by an emotionally charged movie and continuous ratings of the perceived emotion intensity to reveal the topographic organization of affective states. Results show that three orthogonal and spatially overlapping gradients encode the polarity, complexity and intensity of emotional experiences in right temporo-parietal territories. The spatial arrangement of these gradients allows the brain to map a variety of affective states within a single patch of cortex. As this organization resembles how sensory regions represent psychophysical properties (e.g., retinotopy), we propose emotionotopy as a principle of emotion coding

Pentraxin-3 in late-preterm newborns with hypoxic respiratory failure.

The aim of this study was: echocardiographical assessment of cardiac alterations in late-preterm newborns with hypoxic respiratory failure (HRF), and, study serum pentraxin-3 (PTX-3) in relation to the severity of respiratory impairment and to some echocardiographic parameters (i.e. ejection fraction (EF), stroke volume (SV) and cardiac output (CO). We enrolled in this study 40 newborn infants whose 22 (group I) with moderate HRF and 18 (group II) with severe HRF. In group I the mean values of EF, SV and CO were significantly higher than in the group II. Our results showed a significant increase of PTX-3 in group II patients at 24h of life when compared to group I. Taking patients all together (n=40), we found a significant (R=-73) reverse correlation between EF and serum values of PTX-3. PTX-3 in our patients with HRF is affected by the severity of the hypoxic insult and correlate with the cardio-vascular impairment

Common spatiotemporal processing of visual features shapes object representation

none10Biological vision relies on representations of the physical world at different levels of complexity. Relevant features span from simple low-level properties, as contrast and spatial frequencies, to object-based attributes, as shape and category. However, how these features are integrated into coherent percepts is still debated. Moreover, these dimensions often share common biases: for instance, stimuli from the same category (e.g., tools) may have similar shapes. Here, using magnetoencephalography, we revealed the temporal dynamics of feature processing in human subjects attending to objects from six semantic categories. By employing Relative Weights Analysis, we mitigated collinearity between model-based descriptions of stimuli and showed that low-level properties (contrast and spatial frequencies), shape (medial-axis) and category are represented within the same spatial locations early in time: 100-150 ms after stimulus onset. This fast and overlapping processing may result from independent parallel computations, with categorical representation emerging later than the onset of low-level feature processing, yet before shape coding. Categorical information is represented both before and after shape, suggesting a role for this feature in the refinement of categorical matching.nonePapale, Paolo; Betta, Monica; Handjaras, Giacomo; Malfatti, Giulia; Cecchetti, Luca; Rampinini, Alessandra; Pietrini, Pietro; Ricciardi, Emiliano; Turella, Luca; Leo, AndreaPapale, Paolo; Betta, Monica; Handjaras, Giacomo; Malfatti, Giulia; Cecchetti, Luca; Rampinini, Alessandra; Pietrini, Pietro; Ricciardi, Emiliano; Turella, Luca; Leo, Andre

A Wireless, Battery-Powered Probe Based on a Dual-Tier CMOS SPAD Array for Charged Particle Sensing

A compact probe for charged particle imaging, with potential applications in source activity mapping and radio-guided surgery was designed and tested. The development of this technology holds significant implications for medical imaging, offering healthcare professionals accurate and efficient tools for diagnoses and treatments. To fulfill the portability requirements of these applications, the probe was designed for battery operation and wireless communication with a PC. The core sensor is a dual-layer CMOS SPAD detector, fabricated using 150 nm technology, which uses overlapping cells to produce a coincidence signal and reduce the dark count rate (DCR). The sensor is managed and interfaced with a microcontroller, and custom firmware was developed to facilitate communication with the sensor. The performance of the probe was evaluated by characterizing the on-board SPAD detector in terms of the DCR, and the results were consistent with the characterization measurements taken on the same chip samples using a purposely developed benchtop setup