La fonction rénale du chiot et du chien âgé

L'objectif de cette étude est d'évaluer la fonction rénale chez des chiots et des chiens âgés cliniquement sains chez lesquels peu d'informations sont disponibles. Les urines de 24 heures ont été collectées pendant 2 jours sur 10 chiots et 10 de race Beagle âgés de 3 mois et 7 ans en moyenne, respectivement. Les paramètres suivants ont été mesurés : concentrations plasmatiques et urinaires de la créatinine et de divers électrolytes, osmolalité, densité urinaire, protéinurie, clairances fractionnelles et réabsorption de l'eau libre. Le DFG et le DPR ont été évalués par la clairance plasmatique de l'iohexol et du PAH, respectivement. L'analyse statistique des résultats a été réalisée à l'aide de test de Student (p<0,05). Les différences significatives entre les deux groupes étaient les suivantes : DFG : 6.2±0.7 vs 4.1±0.5 mL/kg/min (p=0.000), Fraction plasmatique filtrée : 49.6±9.3 vs 29.8±2.9 % (p=0.000), volume urinaire : 28.7±4.9 vs 16.9±9.2 mL/kg/jour (p=0.000), densité urinaire : 1.042±0.007 vs 1.035±0.008 (p=0.011), osmolalité urinaire : 1572±322 vs 1241±308 mOsm/kg (p=0.000), osmolalité plasmatique : 288±7 vs 303±5 mOsm/kg (p<0.001), protéinurie : 6±1,9 vs 48±68,4 mg/kg (p=0,05), clairance fractionnelle du chlore : 0.5±0.1 vs 0.3±0.1 % (p=0.000), clairance fractionnelle du phosphore : 12±3 vs 18.4±7 % (p=0.021), clairance osmolaire : 1.8±0.4 vs 1.1±0.4 % (p=0.003), Réabsorption de l'eau libre : 0.9±0.2 vs 0.3±0.1 % (p=0.000). Il existe des différences entre les chiots et les chiens âgés concernant les fonctions glomérulaire et tubulaire. Cependant, la fonction rénale des chiens âgés est similaire à celle décrite dans la littérature pour les chiens adultes. L'utilisation des paramètres conventionnels afin d'évaluer la fonction rénale des chiots peut donc prêter à confusion en terme de diagnostic. D'autres études sont néanmoins nécessaires afin de confirmer ces résultats sur de plus grandes populations

Notes on the use of variational autoencoders for speech and audio spectrogram modeling

International audienceVariational autoencoders (VAEs) are powerful (deep) generative artificial neural networks. They have been recently used in several papers for speech and audio processing, in particular for the modeling of speech/audio spectrograms. In these papers, very poor theoretical support is given to justify the chosen data representation and decoder likelihood function or the corresponding cost function used for training the VAE. Yet, a nice theoretical statistical framework exists and has been extensively presented and discussed in papers dealing with nonnegative matrix factorization (NMF) of audio spectrograms and its application to audio source separation. In the present paper, we show how this statistical framework applies to VAE-based speech/audio spectrogram modeling. This provides the latter insights on the choice and interpretability of data representation and model parameterization

Total Dose Effects on Error Rates in Linear Bipolar Systems

The shapes of single event transients in linear bipolar circuits are distorted by exposure to total ionizing dose radiation. Some transients become broader and others become narrower. Such distortions may affect SET system error rates in a radiation environment. If the transients are broadened by TID, the error rate could increase during the course of a mission, a possibility that has implications for hardness assurance

Total Dose Effects on Single Event Transients in Linear Bipolar Systems

Single Event Transients (SETs) originating in linear bipolar integrated circuits are known to undermine the reliability of electronic systems operating in the radiation environment of space. Ionizing particle radiation produces a variety of SETs in linear bipolar circuits. The extent to which these SETs threaten system reliability depends on both their shapes (amplitude and width) and their threshold energies. In general, SETs with large amplitudes and widths are the most likely to propagate from a bipolar circuit's output through a subsystem. The danger these SET pose is that, if they become latched in a follow-on circuit, they could cause an erroneous system response. Long-term exposure of linear bipolar circuits to particle radiation produces total ionizing dose (TID) and/or displacement damage dose (DDD) effects that are characterized by a gradual degradation in some of the circuit's electrical parameters. For example, an operational amplifier's gain-bandwidth product is reduced by exposure to ionizing radiation, and it is this reduction that contributes to the distortion of the SET shapes. In this paper, we compare SETs produced in a pristine LM124 operational amplifier with those produced in one exposed to ionizing radiation for three different operating configurations - voltage follower (VF), inverter with gain (IWG), and non-inverter with gain (NIWG). Each configuration produces a unique set of transient shapes that change following exposure to ionizing radiation. An important finding is that the changes depend on operating configuration; some SETs decrease in amplitude, some remain relatively unchanged, some become narrower and some become broader

The Effects of Low Dose-Rate Ionizing Radiation on the Shapes of Transients in the LM124 Operational Amplifier

Shapes of single event transients (SETs) in a linear bipolar circuit (LM124) change with exposure to total ionizing dose (TID) radiation. SETs shape changes are a direct consequence of TID-induced degradation of bipolar transistor gain. A reduction in transistor gain causes a reduction in the drive current of the current sources in the circuit, and it is the lower drive current that most affects the shapes of large amplitude SETs

Gyroscopic Instability of a Drop Trapped Inside an Inclined Circular Hydraulic Jump

International audienceA drop of moderate size deposited inside a circular hydraulic jump remains trapped at the shock front and does not coalesce with the liquid flowing across the jump. For a small inclination of the plate on which the liquid is impacting, the drop does not always stay at the lowest position and oscillates around it with a sometimes large amplitude, and a frequency that slightly decreases with flow rate. We suggest that this striking behavior is linked to a gyroscopic instability in which the drop tries to keep constant its angular momentum while sliding along the jump

Last Glacial Maximum CO2 and δ13C successfully reconciled

During the Last Glacial Maximum (LGM, ∼21,000 years ago) the cold climate was strongly tied to low atmospheric CO2 concentration (∼190 ppm). Although it is generally assumed that this low CO2 was due to an expansion of the oceanic carbon reservoir, simulating the glacial level has remained a challenge especially with the additional δ13C constraint. Indeed the LGM carbon cycle was also characterized by a modern-like δ13C in the atmosphere and a higher surface to deep Atlantic δ13C gradient indicating probable changes in the thermohaline circulation. Here we show with a model of intermediate complexity, that adding three oceanic mechanisms: brine induced stratification, stratification-dependant diffusion and iron fertilization to the standard glacial simulation (which includes sea level drop, temperature change, carbonate compensation and terrestrial carbon release) decreases CO2 down to the glacial value of ∼190 ppm and simultaneously matches glacial atmospheric and oceanic δ13C inferred from proxy data. LGM CO2 and δ13C can at last be successfully reconciled

Interest of major serum protein removal for Surface-Enhanced Laser Desorption/Ionization – Time Of Flight (SELDI-TOF) proteomic blood profiling

BACKGROUND: Surface-Enhanced Laser Desorption/Ionization – Time Of Flight (SELDI-TOF) has been proposed as new approach for blood biomarker discovery. However, results obtained so far have been often disappointing as this technique still has difficulties to detect low-abundant plasma and serum proteins. RESULTS: We used a serum depletion scheme using chicken antibodies against various abundant proteins to realized a pre-fractionation of serum prior to SELDI-TOF profiling. Depletion of major serum proteins by immunocapture was confirmed by 1D and 2D gel electrophoresis. SELDI-TOF analysis of bound and unbound (depleted) serum fractions revealed that this approach allows the detection of new low abundant protein peaks with satisfactory reproducibility. CONCLUSION: The combination of immunocapture and SELDI-TOF analysis opens new avenues into proteomic profiling for the discovery of blood biomarkers

Intrapulmonary percussive ventilation superimposed on spontaneous breathing: a physiological study in patients at risk for extubation failure

Purpose: Intrapulmonary percussive ventilation (IPV) is a high-frequency ventilation modality that can be superimposed on spontaneous breathing. IPV may diminish respiratory muscle loading and help to mobilize secretions. The aim of this prospective study was to assess the short-term effects of IPV in patients at high risk for extubation failure who were receiving preventive non-invasive ventilation (NIV) after extubation. Methods: Respiratory rate, work of breathing, and gas exchange were evaluated in 17 extubated patients during 20min of IPV and 20min of NIV delivered via a facial mask, separated by periods of spontaneous breathing. The pressure-support level during NIV was adjusted until tidal volume reached 6-8ml/kg and positive end-expiratory pressure (PEEP) 4-5cmH2O. For IPV, the pressurisation frequency was set at 250cycles/min and driving pressure at 1.2bar. The pressure-time product of the diaphragm (PTPdi/min) was measured using an oesophageal and gastric double-balloon catheter. Results: Transdiaphragmatic pressure and PTPdi/min improved significantly (p<0.01), from a median [25th-75th percentiles] of 264 [190-300] to 192 [152-221]cmH2Os/min with IPV and from 273 [212-397] to 176 [120-216]cmH2Os/min with NIV. Respiratory rate decreased significantly from 23 [19-27] to 22 [17-24] breaths/min for IPV and from 25 [19-28] to 20 [18-22] breaths/min for NIV (p<0.01). Mean PaCO2 decreased after NIV (from 46 [42-48] to 41 [36-42]mmHg, p<0.01) but not after IPV. There was no noticeable effect on oxygenation. Conclusions: IPV is an interesting alternative to NIV in patients at risk for post-extubation respiratory failure. Both NIV and IPV diminished the respiratory rate and work of breathing, but IPV was less effective in improving alveolar ventilatio

Local Anodizing of a Newly Prepared Aluminum Micrometric Disk

A search through the literature reveals that the vast majority of studies about aluminum anodizing were conducted at the macroscale (i.e., from cm2 up to m2), while those focused on local anodizing (i.e., on surfaces of less than 1 mm2) are rare. The last ones either used insulating masks or were conducted in an electrolyte droplet. The present study describes on the one hand a new way to prepare aluminum microelectrodes of conventional disk-shaped geometry, and on the other hand the local anodizing of their respective aluminum micrometric top-disks. The influence of the anodizing voltage on anodic film characteristics (i.e., thickness, growth rate and expansion factor) was studied during local anodizing. Compared with the values reported for macroscopic anodizing, the pore diameter appears to be significantly low and the film growth rate can reach atypically high values, both specificities probably resulting from a very limited increase in the temperature on the aluminum surface during anodizing