Snow Processes in Mountain Forests: Interception Modeling for Coarse-Scale Applications

Snow interception by the forest canopy controls the spatial heterogeneity of subcanopy snow accumulation leading to significant differences between forested and nonforested areas at a variety of scales. Snow intercepted by the forest canopy can also drastically change the surface albedo. As such, accurately modeling snow interception is of importance for various model applications such as hydrological, weather, and climate predictions. Due to difficulties in the direct measurements of snow interception, previous empirical snow interception models were developed at just the point scale. The lack of spatially extensive data sets has hindered the validation of snow interception models in different snow climates, forest types, and at various spatial scales and has reduced the accurate representation of snow interception in coarse-scale models. We present two novel empirical models for the spatial mean and one for the standard deviation of snow interception derived from an extensive snow interception data set collected in an evergreen coniferous forest in the Swiss Alps. Besides open-site snowfall, subgrid model input parameters include the standard deviation of the DSM (digital surface model) and/or the sky view factor, both of which can be easily precomputed. Validation of both models was performed with snow interception data sets acquired in geographically different locations under disparate weather conditions. Snow interception data sets from the Rocky Mountains, US, and the French Alps compared well to the modeled snow interception with a normalized root mean square error (NRMSE) for the spatial mean of ≤10 % for both models and NRMSE of the standard deviation of ≤13 %. Compared to a previous model for the spatial mean interception of snow water equivalent, the presented models show improved model performances. Our results indicate that the proposed snow interception models can be applied in coarse land surface model grid cells provided that a sufficiently fine-scale DSM is available to derive subgrid forest parameters

Elaboration de dépôts avec une torche à plasma d'arc pulsé, synchronisée avec une injection jet d'encre

Afin d’améliorer la reproductibilité et la maitrise des procédés SPS (Projection Plasma de Suspension ou Suspension Plasma Spraying) et SPPS (Projection Plasma de Précurseurs en Solution ou Solution Precursors Plasma Spraying), notre équipe travaille sur la compréhension des instabilités du plasma dues en partie au mouvement de l’arc électrique dans les torches à plasma. Des travaux précédents ont mis en évidence l'obtention d'un nouveau mode de résonance qui permet d'obtenir un plasma pulsé avec des oscillations auto-entretenues de la tension d'arc. Un système jet d'encre à la demande piézoélectrique synchronisé avec le plasma est utilisé. Ce dispositif permet à l’aide d’un actionneur piézoélectrique de délivrer une gouttelette à un instant voulu. Il permet d’introduire dans chaque bouffée de plasma une gouttelette déclenchée par les oscillations périodiques de la tension d’arc (~1400 Hz). Ce système permet un traitement en vol reproductible, dans le but d’un contrôle accru de la morphologie et de la composition chimique des dépôts. Des dépôts à partir d’une solution de sel de nitrate ont été réalisés afin de montrer l’intérêt de ce dispositif de synchronisation

Assessment and management of pain/nociception in patients with disorders of consciousness or locked-in syndrome: A narrative review

The assessment and management of pain and nociception is very challenging in patients unable to communicate functionally such as patients with disorders of consciousness (DoC) or in locked-in syndrome (LIS). In a clinical setting, the detection of signs of pain and nociception by the medical staff is therefore essential for the wellbeing and management of these patients. However, there is still a lot unknown and a lack of clear guidelines regarding the assessment, management and treatment of pain and nociception in these populations. The purpose of this narrative review is to examine the current knowledge regarding this issue by covering different topics such as: the neurophysiology of pain and nociception (in healthy subjects and patients), the source and impact of nociception and pain in DoC and LIS and, finally, the assessment and treatment of pain and nociception in these populations. In this review we will also give possible research directions that could help to improve the management of this specific population of severely brain damaged patients

Intracranial aneurismal pulsatility as a new individual criterion for rupture risk evaluation: Biomechanical and numerical approach (IRRAs project).

International audienceThis study was designed to highlight by means of numerical simulations, the correlation between aneurism sac pulsatility and the risk of rupture through the mechanical properties of the wall. In accordance to previous work suggesting a correlation between the risk of rupture and the material properties of cerebral aneurysms, twelve fluid-structure interaction (FSI) computations were performed on 12 "patient-specific" cases, corresponding to typical shapes and locations of cerebral aneurysms. The variations of the aneurismal volume during the cardiac cycle (3V) are compared using wall material characteristics of either degraded and non-degraded tissues. Aneurysms were located on 7 different arteries: Middle Cerebral Artery (4), Anterior Cerebral Artery (3), Internal Carotid Artery (1), Vertebral Artery (1), Ophthalmic Artery (1) and Basilar Artery (1). Aneurysms presented different shapes (uniform or multi-lobulated) and diastolic volumes (from 18 to 392 mm3). The pulsatility (3V/V) was significantly larger for a soft aneurismal material (average of 26 %) than for a stiff material (average of 4 %). The difference between 3V, for each condition, was statistically significant: p = 0.005. The difference in aneurismal pulsatility as highlighted in this work might be a relevant patientspecific predictor of aneurysm risk of rupture

Elevated Electron Temperatures in the Auroral E Layer Measured With the Chatanika Radar

An extensive series of spectral measurements has been made in the auroral E region with the Chatanika incoherent scatter radar. Becasue of the small scale length for variations of electron density, temperatures, and ion-neutral collisions we used the operating mode with the best possible range resolution—9 km. About 5% of the time the data exhibited an unusual spectral shape that was most pronounced at 105 and 110 km. Instead of being almost Gaussian with only a small hint of two peaks, the spectra are much wider, with two well-developed peaks. After carefully considering the validity of the measurements and their interpretation, we conclude that the unusual spectra are due to greatly enhanced electron temperatures. At 110 km, the electron temperature may increase from 250 K to 800 K, while the ion temperature remains near 250 K. This enhancement of the electron temperature extends from 99 km to at least 116 km. We show that the temperature increase is too large to be accounted for by auroral particle precipitation, though it coincides in time with ion temperature enhancements at altitudes above 125 km. Because these latter enhancements are believed to be due to joule heating, we deduce that electric fields of 24-40 mV/m are present and that the electrons are moving through the ions and neutrals at speeds of 500-800 m/s. Despite these velocities, we find that joule heating of the electrons also cannot account for the elevated electron temperatures. Several consequences of the elevated electron temperatures are discussed. One is that the rate constants for molecular recombination are reduced. Another is that during periods of significant joule heating, the deduced electron density profile, when fully corrected for temperatures, has a significantly lower peak altitude and greater density than that deduced under the usual assumption of equal electron and ion temperatures. Since conductivities, currents, ionization rates, and differential energy spectra are dependent upon the density profile, care must be taken to account properly for the temperature effects when deriving these quantities

Multidrug Resistance and Plasmid Patterns of Escherichia coli O157 and Other E. coli Isolated from Diarrhoeal Stools and Surface Waters from Some Selected Sources in Zaria, Nigeria

We have assessed the prevalence of Escherichia coli O157 in diarrhoeal patients and surface waters from some selected sources in Zaria (Nigeria), evaluating the antibiotic susceptibility and plasmid profiles of 184 E. coli isolates, obtained from 228 water samples and 112 diarrhoeal stool specimens (collected from children aged <15 years), using standard methods. The detection rate of E. coli O157 in surface waters was 2.2% and its prevalence in children with diarrhoea was 5.4%. The most active antibiotics were gentamicin, chloramphenicol and fluoroquinolones. Seventy-nine (42.9%) of 184 E. coli isolates were resistant to four or more antibiotics. Multidrug resistance (MDR) was higher amongst aquatic isolates than the clinical isolates. Out of 35 MDR isolates (20 of which were O157 strains), 22 (62.9%) harboured plasmids all of which were no less than 2.1 kb in size. Amongst the 20 E. coli O157 strains, only seven (35.0%) contained multiple plasmids. An aquatic O157 isolate containing two plasmids was resistant to seven drugs, including ampicillin, cefuroxime, ciprofloxacin, cotrimoxazole, nalidixic acid, nitrofurantoin and tetracycline. Loss of plasmid correlated with loss of resistance to antibiotics in cured (mutant) strains selected in tetracycline (50 μg/mL)-nutrient agar plates. Our findings revealed that plasmids were prevalent in both the aquatic and clinical isolates, and suggest that the observed MDR is plasmid-mediated. The occurrence of plasmid-mediated multidrug resistant E. coli O157 in surface waters used as sources for drinking, recreation and fresh produce irrigation heightens public health concern

Photoelectron Flux Build-Up in the Plasmasphere

Processes which confine photoelectrons to the plasmasphere (e.g., collisional backscattering from the thermosphere and magnetic trapping due to pitch angle redistribution through Coulomb collisions in the plasmasphere) tend to increase the steady state photoelectron flux in the plasmasphere above the amplitude level that would otherwise have been attained. Theoretical calculations are presented of steady state photoelectron fluxes in the plasmasphere, for specified atmospheric and ionospheric conditions. (Observational plasma line intensity data for these conditions exist and will be compared elsewhere.) General features of the angular distribution are presented and compared with observations. The transparency of the plasmasphere and the backscattering properties of the thermosphere are investigated. The buildup effect due to collisional backscatter alone is calculated, and the combined buildup effect of pitch angle diffusion and backscatter is estimated. It is found that the inclusion of these effects increases the steady state photoelectron flux amplitude in the plasmasphere by about 50% over the value obtained when the buildup effects are neglected. The calculated steady state photoelectron fluxes in the plasmasphere are in good agreement with the available observations

Intrahost evolution leading to distinct lineages in the upper and lower respiratory tracts during SARS-CoV-2 prolonged infection

Accumulating evidence points to persistent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in immunocompromised individuals as a source of genetically divergent, novel lineages, generally characterised by increased transmissibility and immune escape. While intrahost evolutionary dynamics of the virus in chronically infected patients have been previously reported, existing knowledge is primarily based on samples obtained from the nasopharyngeal compartment. In this study, we investigate the intrahost evolution and genetic diversity that accumulated during a prolonged SARS-CoV-2 infection with the Omicron sublineage BF.7, estimated to have persisted for over one year in an immunosuppressed patient. Based on the sequencing of eight viral genomes collected from the patient at six time points, we identified 86 intrahost single-nucleotide variants (iSNVs), two indels, and a 362 bp deletion. Our analysis revealed distinct viral genotypes in the nasopharyngeal (NP), endotracheal aspirate (ETA), and bronchoalveolar (BAL) samples. Notably, while significant divergence was observed between NP and BAL samples, most of the iSNVs found in ETA samples were also detected in NP or BAL samples. This suggests that NP samples may not offer a comprehensive representation of the overall intrahost viral diversity. Nonsynonymous mutations were most frequent in the spike and envelope genes, along with loss-of-function mutations in ORF8, generated by a frameshift mutation and a large deletion detected in the BAL and NP samples, respectively. Using long-range PCR on SARS-CoV-2 samples sequenced as part of routine surveillance, we validated that similar deletions causing ORF8 loss of function can be carried by SARS-CoV-2 during acute infection. Our findings not only demonstrate that the Omicron sublineage BF.7 can further diverge from its already exceptionally mutated state but also highlight that patients chronically infected with SARS-CoV-2 can develop genetically specific viral populations across distinct anatomical compartments. This provides novel insights into the intricate nature of viral diversity and evolution dynamics in persistent infections