Search

The Seebeck and Soret coefficients of ionically stabilized suspension of maghemite nanoparticles in dimethyl sulfoxide are experimentally studied as a function of nanoparticle volume fraction. In the presence of a temperature gradient, the charged colloidal nanoparticles experience both thermal drift due to their interactions with the solvent and electric forces proportional to the internal thermoelectric field. The resulting thermodiffusion of nanoparticles is observed through forced Rayleigh scattering measurements, while the thermoelectric field is accessed through voltage measurements in a thermocell. Both techniques provide independent estimates of nanoparticle's entropy of transfer as high as 82 meV K-1. Such a property may be used to improve the thermoelectric coefficients in liquid thermocells. [ABSTRACT FROM AUTHOR]

The acceptability of autonomous vehicles is an important issue for car manufacturers. The subject of this work attempts to address this issue in the context of conflict situations in urban environments. We present the results of a preliminary study that was conducted to investigate the effects of the driving mode and context on the acceptability of the behavior of an autonomous vehicle. We thus measured acceptability on 30 drivers confronted with three driving modes (defensive, aggressive, and transgressive) as well as different situations constituted by the most common urban intersections in France. We then formulated hypotheses on the effects that the driving mode, the context, or the socio-demographic characteristics of the passengers may have on their acceptability of the autonomous vehicle behavior. In the context of our study, the driving mode of the vehicle was the most influential parameter on the level of acceptability assessed by the participants. The type of intersection used did not result in a significant difference, nor did the socio-demographic characteristics studied. The results of these works allow an interesting first approach and lead us to guide our future works on the study of the parameters involved in the driving modes of autonomous vehicles., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In a turbulent fluid, the time-reversal symmetry is explicitly broken by viscosity, and spontaneously broken in the inviscid limit. Recently, Drivas [J. Nonlinear Sci. 29, 65 (2019).JNSCEK0938-897410.1007/s00332-018-9476-8] proved the equivalence of two different local indicators of time irreversibility: (i) an Eulerian one, based on regularity properties of the velocity field [Duchon and Robert, Nonlinearity 13, 249 (2000).NONLE50951-771510.1088/0951-7715/13/1/312]; (ii) a Lagrangian one, based on symmetry properties of the trajectories under time reversal [Jucha et al., Phys. Rev. Lett. 113, 054501 (2014).PRLTAO0031-900710.1103/PhysRevLett.113.054501]. We test this equivalence in a turbulent Von Kármán experiment at a resolution of the order of the Kolmogorov scale using a high resolution 4D-PTV technique. We use the equivalence to perform the first joined Eulerian-Lagrangian exploration of the dynamics leading to time irreversibility, and find that it is linked with vortex interaction, suggesting a link between irreversibility and singularity.

Although campaigns promoting organ donation have proved their effectiveness, increasing the number of people who explicitly agree to become donors is still difficult. Based on the social marketing notion of persuasive technology, we reasoned that it was timely to focus on the design of this persuasive technology and to analyze its contribution in particularly challenging contexts such as organ donation. More specifically, the originality of the present study lay in the way we linked the field of persuasive technology to the theory of social representations, and combined them with an analysis of the ergonomic aspects of interface layout. This study had two complementary goals. The first was to determine whether the sociocognitive salience of the central elements of social representations (i.e., the most frequent and important themes related to the subject-here, organ donation-for individuals), can be used to achieve persuasive outcomes. The second was to determine whether interface layout, in terms of information location and background characteristics (color and contrast), can strengthen the persuasive impact. University students (N > 200) were exposed to a computer screen displaying a message involving either central or peripheral elements of the social representations of organ donation (status), placed either in the middle or on one side of the screen (location), and shown against either a white or a blue background (background). Eye-tracking data were recorded, in addition to self-reported data. In line with the elaboration likelihood model, results showed that participants who were exposed to central (vs. peripheral) elements of the social representations of organ donation followed the central route in processing information. Moreover, they had stronger attitudes, and more of them stated that they were actual organ donors. Importantly, however, at least for some variables, these status-related effects were not independent of the interface layout. More specifically, the persuasive impact of the central elements was enhanced when the information was displayed in the middle (vs. the side) of the screen and when it was displayed on a white (vs. blue) background. We discuss the theoretical and practical issues raised by these results., Competing Interests: The authors have declared that no competing interests exist.

Currently, liquid thermocells are receiving increasing attention as an inexpensive alternative to conventional solid-state thermoelectrics for low-grade waste heat recovery applications. Here we present a novel path to increase the Seebeck coefficient of liquid thermoelectric materials using charged colloidal suspensions; namely, ionically stabilized magnetic nanoparticles (ferrofluids) dispersed in aqueous potassium ferro-/ferri-cyanide electrolytes. The dependency of thermoelectric potential on experimental parameters such as nanoparticle concentration and types of solute ions (lithium citrate and tetrabutylammonium citrate) is examined to reveal the relative contributions from the thermogalvanic potential of redox couples and the entropy of transfer of nanoparticles and ions. The results show that under specific ionic conditions, the inclusion of magnetic nanoparticles can lead to an enhancement of the ferrofluid's initial Seebeck coefficient by 15% (at a nanoparticle volume fraction of ∼1%). Based on these observations, some practical directions are given on which ionic and colloidal parameters to adjust for improving the Seebeck coefficients of liquid thermoelectric materials.

A thermally chargeable capacitor containing a binary solution of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide in acetonitrile is electrically charged by applying a temperature gradient to two ideally polarisable electrodes. The corresponding thermoelectric coefficient is -1.7 mV/K for platinum foil electrodes and -0.3 mV/K for nanoporous carbon electrodes. Stored electrical energy is extracted by discharging the capacitor through a resistor. The measured capacitance of the electrode/ionic-liquid interface is 5 μF for each platinum electrode while it becomes four orders of magnitude larger, ≈36 mF, for a single nanoporous carbon electrode. Reproducibility of the effect through repeated charging-discharging cycles under a steady-state temperature gradient demonstrates the robustness of the electrical charging process at the liquid/electrode interface. The acceleration of the charging by convective flows is also observed. This offers the possibility to convert waste-heat into electric energy without exchanging electrons between ions and electrodes, in contrast to what occurs in most thermogalvanic cells.

Several studies have served to underline the interest of MRI in the diagnosis and assessment of epidural abscess and malignant extradural spinal tumors. In our work, one of the quantitatively greatest published to this day, 64 patients presenting epidural pathology were evaluated by means of MRI. All the explorations were brought about through weighted multiplaned sequences T1, T2 and gadolinium injection. The pathological spectrum encountered is comprised of: metastatic extradural spinal tumors (58%), primary extradural spinal tumors (7%), epidural localizations of hematological diseases (9%), epidural abscess (25%), and one case of epidural hematoma. Assessment was brought to bear upon behavior in relation to type of sequence, spread of disease, medullary effects, type of enhancement following gadolinium injection. Degree of correlation with clinical data and surgical findings was also appraised. As concerns tumourous epidural pathology, positive diagnosis due to a lesion hinges upon the T1 and T2 sequences. Gadolinium's contribution is restricted to analysis of perivertebral and vertebral spreading; it also facilitates recognition of the spinal cord in circumferential epiduritis. So much said, gadolinium appears to be essential in frequently less compressive forms of infectious epiduritis; it plays a pronounced role in both follow-up of their evolution and recognition of acute epidural hematoma.

Adamantinoma of the long bones in a very rare tumor that mainly affects the tibia. Its diagnosis is difficult both radiologically, as the lesion appears as a poorly specific metaphyseal lacuna with or without periosteal reaction, and histologically. Its prognosis used to be guarded because of recurrence and of possible metastatic diffusion, but it has been considerably improved by wide resection with reconstruction. On the occasion of a new case, the authors describe the appearance observed with MRI and the merits of this examination for the preoperative assessment.

As leiomyosarcomas of the inferior vena cava are extremely infrequent, the preoperative diagnosis of such tumors is rarely established. We report two cases in which the diagnosis was suggested by modern imaging prior to surgery. Three examination techniques allo contemplating this diagnosis. Ultrasound and cavography show either an intraluminal, multilobulated, roughly hyperechogenic lacuna on one of the segments of the vena cava, without any remote thrombosis image, or a complete obstruction of the vena cava with collateral circulation and a hyperechogenic right paraaortic mass. Computed tomography demonstrates the extraluminal extension. It reveals the presence of a right lateroaortic tumor with heterogeneous tissue density, in which the vena cava is concealed. The association of an intraluminal lacuna and of a tumoral syndrome on CT is highly suggestive. These three techniques are equally essential for the assessment of this tumor, which is primarily based on vascular findings. Exeresis is always difficult and the prognosis very poor.

378 tomodensitometric investigations were performed in cases of acute pancreatitis. The evolution of inflammatory lesions were analyzed with special attention to tissue aggressive inflammation in order to recognize early signs of gravity on CAT scans. Pancreatic lesions less than 15 mm in diameter called "hypodense islets-1" are compatible with oedematous lesions while lesions greater than 15 mm in diameter ("hypodense islets-2") are characteristic of developing necrosis. Tissue aggressive inflammatory lesions were classified in five grades retrospectively and showed that the incidence of abcesses was greater in grade II (76.5%) than in grade I lesions (11.75%).

Chronic rhinosinusitis endoscopic surgery needs an accurate evaluation of diseases and paranasal sinus anatomic variations. High resolution CT by thin section (2 mm) allow this pre-operative assessment. An anatomical study of the ethmoid air cell system is always possible in axial plane. The bidimensional CT exploration (axial and coronal plane) displays the anatomic variations of ostiomeatal unit, that have been reported to predispose sinusitis. They are nasal septal deviation, pneumatization and paradoxical curvature of the middle turbinate, pneumatization of unciform process, Haller's cells, prominent agger nasi cell and ethmoid bulla. The endoscopic endonasal surgery landmarks, the individual morphologic variations, the topographic relations to the orbit and to the brain are also well shown by CT.

The development of disk or epidural calcifications is a frequent possibility following intra-disk injection of triamcinolone hexacetonide. It was found 10 times in 26 follow-up CT scans obtained 2 to 3 years after the injection. These calcifications are often clinically silent, but they sometimes accompany a recurrence of the initial painful symptomatology. Furthermore, evaluation at 3 years of therapeutic results in a previously published series of patients who had received an intra-disk injection of triamcinolone hexacetonide showed a marked decrease in favourable results (30% vs 67% at 6 months). These two arguments: disappointing long term results and possibility of disk calcifications, are felt by the authors to justify abandoning the technique of triamcinolone hexacetonide by intra-disk injection in the treatment of lumbar disk prolapse.

The advance of endoscopic endonasal surgery allows limited surgical resection in chronic rhinosinusitis. An accurate topographic evaluation of diseases and individual morphologic variation are necessary for this functional surgery. The preoperative radiological investigations require a precise knowledge of ethmoid and osteo-meatal unit anatomy. Thin sections by high resolution CT were performed in coronal plane. The anatomical land marks and the ethmoidal bony roots, which allow a study of the osteo-meatal unit and ethmoid air cells system, are showed. Like endoscopic view, coronal slices better display the different grooves for paranasal sinus draining and their relations with the ethmoid.

A case of chondrosarcoma arising from the 7th left rib in a patient with multiple exostosis disease is reported. The initial CT scan feature is a purely intrathoracic mass with a parietal and pericardial junction and calcifications within the tumor. A review of the literature about the costal chondrosarcoma and their CT scan features is done and shows the uncommon initial aspect of this case.

Computed tomography is currently the most effective method for investigating the pancreas. Though far from superseding ultrasonography, which should always precede it, possible insufficiences of this examination can be corrected and doubtful images clarified. Its greatest usefulness is in acute pancreatitis, as the size of the lesion can be defined as well as subsequent therapeutic measures. It also appears to be the most reliable examination for chronic pancreatitis or cancer of the pancreas at the present time, but their differential diagnosis can raise problems when certain localized hypertrophic lesions exist. However, diagnosis of a pancreatic lesion is only possible when it deforms the gland or modifies its density, and it is illusory to expect early detection of lesions less than 2 or 3 cm in diameter, particularly in cancer cases.

Three methods are currently employed for the diagnosis of sciatica due to disc lesions: radiculography, spinal phlebography, and computed tomography. Though their indications vary according to the author, it seemed worthwhile to compare radiation delivered by each of them, because of the often young age of the patients. Dosimetric studies using a Rando Phantom enabled calculation of doses to the skin, spinal cord, and gonads. Results indicated that low doses were delivered by the scanner, relatively high doses by spinal phlebography, and intermediate doses by radiculography. These findings suggest that the initial examination preoperatively in cases of simple sciatica due to herniated disc should be a CT scan whenever possible. Phlebography, on the contrary, and particularly in young women, should be used only exceptionally, as a result of the high doses delivered to the ovaries even during technically simple explorations.

An original aspect of a case of atheromatous aneurysm of an aberrant right subclavian artery was the evaluation of the complementary diagnostic value of CT scan and intravenous digital subtraction angiography imaging. The vascular anomaly was clearly identified, the CT scan visualizing the aneurysm sac more effectively and the angiography providing a vascular cartography. These two non-invasive exploratory examinations provide complementary data for the preoperative diagnosis and investigation of the aberrant right subclavian artery aneurysm.

Findings in a series of 53 examinations performed in patients with extrahepatic cholestasis demonstrated the value of computed tomography exploration to determine mechanisms and etiology of biliary tract affections. Sensitivity of the CT scan for detection of biliary tract dilatations was equivalent to that obtained by ultrasound, and was even higher for certain types of patient (obese, distended, etc.). Results of this study combined with data in the literature enables precise diagnostic criteria to be established when determining etiology of these dilatations, which require investigation by a CT scan when ultrasound imaging proves unsatisfactory.

A case of azygos vein aneurysm is described. It is a very rare condition, this being the tenth reported case. The patient presented with superior vena cava obstruction and underwent successful surgical cure. This congenital malformation is practically always latent. The aneurysm is usually diagnosed after the discovery of a mediastinal mass on routine chest X ray. Although its variations in size with position and respiration are characteristic, angiography would seem to be essential to confirm its aneurysmal nature and the anatomical relationships. Surgery is usually simple and should be proposed even to asymptomatic patients because of the risk of thromboembolism.