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The aim of this study was to estimate the incidence of COVID-19 disease in the French national population of dialysis patients, their course of illness and to identify the risk factors associated with mortality. Our study included all patients on dialysis recorded in the French REIN Registry in April 2020. Clinical characteristics at last follow-up and the evolution of COVID-19 illness severity over time were recorded for diagnosed cases (either suspicious clinical symptoms, characteristic signs on the chest scan or a positive reverse transcription polymerase chain reaction) for SARS-CoV-2. A total of 1,621 infected patients were reported on the REIN registry from March 16th, 2020 to May 4th, 2020. Of these, 344 died. The prevalence of COVID-19 patients varied from less than 1% to 10% between regions. The probability of being a case was higher in males, patients with diabetes, those in need of assistance for transfer or treated at a self-care unit. Dialysis at home was associated with a lower probability of being infected as was being a smoker, a former smoker, having an active malignancy, or peripheral vascular disease. Mortality in diagnosed cases (21%) was associated with the same causes as in the general population. Higher age, hypoalbuminemia and the presence of an ischemic heart disease were statistically independently associated with a higher risk of death. Being treated at a selfcare unit was associated with a lower risk. Thus, our study showed a relatively low frequency of COVID-19 among dialysis patients contrary to what might have been assumed., Graphical abstract

The change of western countries’ agricultural models is an increasingly needed endeavor. Alternatives to conventional farming practices exist, but only a few farmers have been able to bring about structural change in their farming system. Beyond the technical issue, studies have highlighted the numerous socio-economic barriers farmers may face when envisioning practices change. More precisely, farmers are nowadays at the crossroad of diverse obstacles, visions and interests, indicating that the transition of practices needs to be tackled at a collective level. The present study aims at understanding better how the role of stakeholders of different nature intervenes during the trajectory of farmers who have already engaged practices change. Around thirty interviews of farmers were carried out in the plains of Limagne to assess the territorial dynamics supporting these changes. The results of the study show that the stakeholders involved are slowly shifting in the support given to organic farming conversion while nearly none exist at territory-level when farmers implement conservation agriculture techniques. The local context of the Limagne plains, with the structural presence of Limagrain Company, let foresee long-term lock-ins in the dissemination of more environmental-friendly practices.

International audience; This paper deals with the numerical investigation of the unilateral contact-induced dynamics of a turbomachine blade rotating within a perfectly rigid yet distorted casing. This investigation is motivated by unelucidated vibratory behaviours observed experimentally. The simulations are based on an in-house time-marching strategy incorporating Lagrange multipliers for the unilateral contact treatment, as well as centrifugal stiffening and abradable coating removal. Significant extensions are proposed through the implementation of (1) aerodynamic loading on the blade and (2) post-processing techniques involving the empirical mode decomposition which provides fruitful insights on important transient phenomena. A thorough bifurcation analysis with and without aerodynamic loading highlights the existence of flip bifurcations with period-doubling and period-halving sequences over a broad angular speed range. Numerical simulations with external aerodynamic loading yield quasi-periodic and likely to be chaotic motions that could not be observed under vacuum. The proposed numerical investigations underline the key role of the aerodynamic loading in the blade dynamics and suggest that unexplained experimental vibratory behaviours are related to the vacuum conditions of the experiment.; Cet article porte sur des investigations numériques relativement à la réponse vibratoire d’une aube de turbomachine, suite à des contacts structuraux. Le carter environnant est déformé mais supposé infiniment rigide. Ces travaux sont motivés par l’observation expérimentale de plusieurs phénomènes vibratoires qui restent inexpliqués. Les simulations effectuées reposent sur l’utilisation d’un outil numérique développé au laboratoire combinant un algorithme de calcul de multiplicateurs de Lagrange pour le traitement du contact et la prise en compte des effets centrifuges et de l’arrachement du revêtement abradable. Des ajouts majeurs à cet outil sont proposés avec l’implémentation de: (1) la prise en compte d’un chargement aérodynamique sur l’aube et (2) le post-traitement des résultats par l’intermédiaire de méthodes de décomposition en modes empiriques qui permettent de mieux analyser les phénomènes transitoires. Une analyse de stabilité avec et sans chargement aérodynamique met en évidence l’existence de points de bifurcation sur une large plage de vitesses de rotation. Les simulations numériques prenant en compte le chargement aérodynamique permettent d’observer des mouvements quasi-périodiques et d’autres probablement chaotiques qui n’ont jamais été observé sous vide.

Large cohort studies suggest that high convective volumes associated with online hemodiafiltration may reduce the risk of mortality/morbidity compared to optimal high-flux hemodialysis. By contrast, intradialytic tolerance is not well studied. The aim of the FRENCHIE (French Convective versus Hemodialysis in Elderly) study was to compare high-flux hemodialysis and online hemodiafiltration in terms of intradialytic tolerance. In this prospective, open-label randomized controlled trial, 381 elderly chronic hemodialysis patients (over age 65) were randomly assigned in a one-to-one ratio to either high-flux hemodialysis or online hemodiafiltration. The primary outcome was intradialytic tolerance (day 30-day 120). Secondary outcomes included health-related quality of life, cardiovascular risk biomarkers, morbidity, and mortality. During the observational period for intradialytic tolerance, 85% and 84% of patients in high-flux hemodialysis and online hemodiafiltration arms, respectively, experienced at least one adverse event without significant difference between groups. As exploratory analysis, intradialytic tolerance was also studied, considering the sessions as a statistical unit according to treatment actually received. Over a total of 11,981 sessions, 2,935 were complicated by the occurrence of at least one adverse event, with a significantly lower occurrence in online hemodiafiltration with fewer episodes of intradialytic symptomatic hypotension and muscle cramps. By contrast, health-related quality of life, morbidity, and mortality were not different in both groups. An improvement in the control of metabolic bone disease biomarkers and β2-microglobulin level without change in serum albumin concentration was observed with online hemodiafiltration. Thus, overall outcomes favor online hemodiafiltration over high-flux hemodialysis in the elderly.

International audience; The main purpose of this paper is to present an experimental setup dedicated to the study of high speed interactions such as those occurring between the rotating blade and the casing of an aircraft engine compressor. A simplified approach of rotor/stator interaction was experimentally simulated for ranges of velocities and interaction depths varying from 60 m/s to 270 m/s and from 0.13 mm to 0.35 mm respectively. Only high speed orthogonal contact were studied. The device was made up of a ballistic bench projecting a sample of abradable material (M601) against an instrumented tool (Steel 42CrMo4) representing the simplified blade shape. In order to increase significantly the measurement system bandwidth and to measure accurately the high speed interaction forces, a correction method based on the principle of modal analysis was developed and successfully employed. This work provides new experimental data regarding the material behavior of M601 in high speed orthogonal cutting conditions. They were in good agreement with those already observed in the literature for velocities up to 100 m/s. These new results showed the non-linear increase of the mean interaction force with the velocity and incursion depth for the large range of velocities considered in this present work. Post-experiment observations gave evidence of two wear mechanisms: cutting and plastic deformation.

BACKGROUND: Little is known on outcomes after transition to adult care among adolescents with perinatal HIV infection. Though there is data from other chronic pediatric diseases suggesting increased morbidity and mortality following transfer to adult care, this has not well been studied among the first wave of survivors of perinatal HIV infection. The primary objective of this study was to determine outcomes after transition to adult care among a cohort of HIV-infected adolescents in Québec, Canada. Secondary objectives were to document participant experiences with the transition process, identify barriers to successful transition, and potential changes to improve the transition process. METHODS: Clinic records were reviewed to identify all perinatally-infected youth who transitioned from the Centre Maternel et Infantile sur le Sida pediatric HIV clinic (Montreal) at age 18 to an adult care provider between 1999 and 2012. Transitioned patients were contacted using last available patient or parental listed phone number on hospital record, internet based telephone directory, or social media. A standardized questionnaire was administered by telephone or in-person interview, and copies of current medical records obtained from treating physicians. RESULTS: Forty-five patients were transferred between 1999 and 2012, among whom 25 consented to the study, eight were lost to follow-up, eight refused participation, and four were deceased. Overall 76 % of patients remained engaged in care, defined by at least one physician visit within 6 months of the interview. Over 50 % reported difficulty with adherence to their current drug regimens. At one-year post-transfer, there was a decrease in the proportion of patients with CD4 count >500 cells/mm(3) from 64 to 29 %, and a statistically significant decrease in absolute CD4 count (mean 370 vs 524 cells/mm(3), p = 0.04.). The majority (92 %) of participants felt that 18 was too young an age to transfer to adult care, and provided suggestions for improving the transition process. CONCLUSIONS: This group of perinatally-infected youth remained engaged in care after transition, however difficulties with adherence and assuming responsibility for their own care were identified as issues in their post-transition care. The high rate of mortality among them and the changes to their health status post-transition suggest that further work is necessary to document the health outcomes of this group in larger, more diverse cohort settings.

Background: Darbepoetin alfa is an erythropoiesis-stimulating agent (ESA) used either intravenously or subcutaneously with no dose penalty; however, the direct switch from subcutaneous recombinant human erythropoietin (rHuEPO) to intravenous darbepoetin has barely been studied. Objective: To establish the equivalence of a direct switch from subcutaneous rHuEPO to intravenous darbepoetin versus an indirect switch from subcutaneous rHuEPO to intravenous darbepoetin after 2 months of subcutaneous darbepoetin in patients undergoing hemodialysis. Methods: In this open, randomized, 6-month, prospective study, patients with end-stage kidney disease who were on hemodialysis were randomized into 2 groups: direct switch from subcutaneous rHuEPO to intravenous darbepoetin (group 1) and indirect switch from subcutaneous rHuEPO to intravenous darbepoetin after 2 months of subcutaneous darbepoetin (group 2). A third, nonrandomized group (control), consisting of patients treated with intravenous rHuEPO who were switched to intravenous darbepoetin, was also studied to reflect possible variations of hemoglobin (Hb) levels due to change from one type of ESA to the other. The primary outcome was the proportion of patients with stable Hb levels at month 6. Secondary endpoints included Hb stability at month 3, dosage requirements for darbepoetin, and safety of the administration route. Results: Among 154 randomized patients, the percentages with stable Hb levels were equivalent in groups 1 and 2, respectively, at month 3 (86.0% vs 91.3%) and month 6 (82.1% vs 81.6%; difference –0.5 [90% CI –12.8 to 11.8]). Mean Hb levels between baseline and month 6 remained stable in both groups, with no variation in mean darbepoetin dose. Mean ferritin levels remained above 100 μg/L in the 3 groups during the whole study, and darbepoetin was well tolerated. Conclusions: This study has shown equivalent efficacy on Hb stability without the need for dosage increase in patients switched directly from subcutaneous rHuEPO to intravenous darbepoetin.

International audience; Aircraft engine manufacturers are developping a new generation of turbojet engines featuring a lower impact on the environment, increased performances as well as reduced gas consumption. The efficiency of an engine is mostly driven by the operating clearance between the rotating parts and the stator. Accordingly, modern designs focus on the minimization of these clearances. In this context, unavoidable rotor imbalances or mistuning stemming from manufacturing processes as well as distortions resulting from thermal expansion or assembly conditions may generate blade-tip/casing contacts that are now considered as non-accidental operating conditions. In order to minimize the consequences of such events, an abradable coating is sprayed along the inner surface of the casing and acts as a fuse when the blade and the casing are in contact. However, even when an abradable coating is used, significant structural damages and wear as well as blade failures have been witnessed experimentally. The understanding of the physical phenomena at play called, on one hand, for throrough experimental investigations of rotor/stator contacts on full-scale stages of compressors and underlined that blade failure is mainly due to vibratory fatigue although the abradable coating is worn. On the other hand, numerical simulations have been performed to better understand the blade dynamics: over the last decade Snecma and its academic partners jointly developed a code for the simulation of COntacts between ROtor and Stator: COROS. This code allows for the simulation of contacts—with a Lagrange multiplier contact treatment procedure—between full 3D models of engine components and accounts for abradable coating material removal. In particular, the simulation of experimental setups with COROS highlighted the correlation between the blade vibratory response and the abradable material removal. Yet still an experimental code, this paper addresses the integration of COROS within the design process of aircraft engine blades at Snecma. The paper focuses on ongoing research for the identification of critical parameters in the arising of interactions as early as the design stage of components. A particular attention is paid to the mechanical properties of the abradable coating for which both experimental and numerical investigations are detailed.

International audience; The purpose of the present paper is to study interaction phenomena between an abradable material (M601) and a titanium alloy (TA6V). This interaction which can occur in an aircraft engine when the rotating blade tips rub on the compressor casing, is analyzed on an experimental laboratory set-up. Only orthogonal cutting conditions are considered in this preliminary study to monitor the load evolution with velocity. The experimental results obtained for a range of velocities $10 < V < 10^7$ m/s and for a range interaction depth $0.05 < t_1 < 0.5$ mm are presented. After analysis of measurements, the mean interaction force increases proportionally to the interaction depth increment. The effects of the contact geometry on the loads, especially the radius of the edge, are investigated. The increase of the radius value for a given interaction depth increases the load value.This work provides new basic data for behaviour laws introduced in numerical models simulating the interaction between the blade tip and the compressor casing in turbine engine applications. Original high-speed photographs recorded in real time during the process illustrate the chip separation by brittle manner. A temperature field in the abradable material will be able to be obtained for only a low speed of 5 m/s.

International audience; Recent studies focused on the numerical prediction of structural instabilities that may arise in rotating components of an aircraft engine. These instabilities are commonly classified into two categories: those induced by aerodynamic phenomena (such as the pressure applied on the blade by the incoming air flow) and those related to structural phenomena (such as potential blade/casing contacts). Based on an existing numerical strategy for the analysis of rotor/stator interactions induced by unilateral contacts between rotating and static components, this paper aims at combining both types of instabilities and provides a qualitative analysis of structural interactions that may arise within the high-pressure compressor of an aircraft engine. The aerodynamic pressure on the blade is simplified as a sinusoidal external load whose frequency depends on the number of upstream guide vanes. Results are presented both in time and frequency domains. Detailed bifurcation diagrams and Poincaré maps underline the fundamental differences in the nature of the witnessed interactions with and without aerodynamic loading on the blade.; Plusieurs etudes récentes ont eu pour objet la simulation numérique des instabilités structurelles pouvant survenir dans des machines tournantes telles que des moteurs d'avion. Typiquement, ces instabilités sont séparées en deux catégories : celles relatives aux phénom enes aérodynamiques (liés par exemplè a la pression imposée sur l'aube par le flux d'air) et celles relatives a des phénom enes uniquement structurels (comme le contact aube/carter). En se basant sur l'utilisation d'une méthode numérique dédiéè a l'analyse d'interactions aube/carter initiées par des contacts entre parties tournante et fixe, les travaux présentés dans cet article ont pour objectif d'analyser conjointement les deux types d'instabilité précédemment citées et de fournir une analyse qualitative des types de régimes d'interactions pouvant survenir dans un moteur d'avion. La pression aérodynamique est modéliséè a l'aide d'un chargement externe d'amplitude sinuso¨dale et dont la fréquence dépend du nombre de redresseurs en aval. Les résultats sont donnés dans les espace temporel et fréquentiel. Les différences fondamentales de nature entre les différentes interactions simulées avec et sans pression aérodynamique sont mises en evidence par des diagrammes de bifurcation détaillés et des cartes de Poincaré.

Recent numerical developments dedicated to the simulation of rotor/stator interaction involving direct structural contacts have been integrated within the Snecma industrial environment. This paper presents the first attempt to benefit from these developments and account for structural blade/casing contacts at the design stage of a high-pressure compressor blade. The blade of interest underwent structural divergence after blade/abradable coating contact occurrences on a rig test. The design improvements were carried out in several steps with significant modifications of the blade stacking law while maintaining aerodynamic performance of the original blade design. After a brief presentation of the proposed design strategy, basic concepts associated with the design variations are recalled. The iterated profiles are then numerically investigated and compared with respect to key structural criteria such as: (1) their mass, (2) the residual stresses stemming from centrifugal stiffening, (3) the vibratory level under aerodynamic forced response and (4) the vibratory levels when unilateral contact occurs. Significant improvements of the final blade design are found: the need for an early integration of nonlinear structural interactions criteria in the design stage of modern aircraft engines components is highlighted.Copyright © 2014 by ASME

Combined antiretroviral therapy allows children with human immunodeficiency virus (HIV) to reach adulthood. We studied 45 adolescents at the time of transfer to adult care. Despite universal healthcare access, over two-thirds of the adolescents were failing treatment, which was manifested by detectable HIV-1 viral load, CD4 counts

International audience; Higher aircraft energy efficiency may be achieved by minimizing the clearance between the rotating blade tips and respective surrounding casing. A common technical solution consists in the implementation of an abradable liner which improves both the operational safety and the efficiency of modern turbomachines. However, unexpected abradable wear removal mechanisms were recently observed in experimental set-ups as well as duringmaintenance procedures. Based on a numerical strategy previously developed, the present study introduces a numerical-experimental comparison of such occurrence. Attention is first paid to the review and analysis of existing experimental results. Good agreement with numerical predictions is then illustrated in terms of critical stress levels within the blade as well as final wear profiles of the abradable liner. Numerical results suggest an alteration of the abradablemechanical properties in order to explain the outbreak of a divergent interaction. New blade designs are also explored in this respect and it is found that the interaction phenomenon is highly sensitive to (1) the blade geometry, (2) the abradablematerial properties and (3) the distortion of the casing.

Paper GT2012-68171Volume 7: Structures and Dynamics, Parts A and BConference Sponsors: International Gas Turbine InstituteISBN: 978-0-7918-4473-1; International audience; Higher aircraft energy efficiency may be achieved by minimizing the clearance between the rotating blade tips and respective surrounding casing. A common technical solution consists in the implementation of an abradable liner which improves both the operational safety and the efficiency of modern turbomachines. Recently, unexpected abradable wear removal mechanisms were observed in experimental set-ups and duringmaintenance procedures. The present study introduces a numerical strategy capable to address this occurrence. After focusing on the analysis of the experimental results, the good agreement between experimental observations and numerical results is illustrated in terms of critical stress levelswithin the blade as well as final wear profiles of the abradable liner. New blade designs are also explored in order to assess the impact of blade design on the outbreak of the interaction phenomenon. The prevalence of three dominant parameters in the interaction onset is shown: (1) blade design, (2) abradable material mechanical properties and (3) the need for a global distortion of the casing to synchronize blade-tip/abradable coating contacts.

International audience; In rotating machinery, notably in modern high efficiency compressors, a critical requirement for optimal performance consists in minimizing radial clearances between the rotating bladed disk and the casing. This solution significantly increases the risks of contact between rotating bladed disk and casing and may lead in specific conditions to catastrophic behavior (component failure, etc.). The physical phenomena and mechanisms involved in blade-casing contact interaction situations are still misunderstood. In order to highlight these mechanisms, specific experiments have been performed on an experimental multi-stage compressor of a turbojet with dedicated dynamic and thermal instrumentations. For all configurations tested, major damages are noticed: blades had cracks and the abradable coating of the casing was heavily machined. Results show that the blade failure refers to fatigue limit with first natural mode excitation of the blade. The paper is focused on the analysis of the successive stages of blade dynamic response before the failure. It is shown that this response is influenced by the variations of the blade-casing contact conditions. These conditions are linked to the thermomechanical behavior and wear of coating, illustrated by high thermal levels and non uniform wear profile. Coupling between thermomechanics, wear and dynamic has to be considered to highlight the transient mechanisms leading to the cases of blade failure.

International audience; Grevillea robusta, a Kenyan wood species of low durability was heat treated under inert atmosphere in laboratory conditions at temperatures between 220 and 250 degrees C. Modulus of rupture (MOR) and modulus of elasticity (MOE) were determined for different heat treatment conditions. MOR and MOE reduced with increase in heat treatment weight loss. MOE reduced insignificantly for weight loss less than 16% while reduction of MOR was more significant. For a fixed heat treatment temperature by varying the treatment duration, sugar content was analysed by HPLC after acidic hydrolysis and Mason lignin was determined. The amount of sugars other than glucose decreased with treatment time and was near zero after 7 h, while lignin quantity increased gradually. Wood acidity determined by titration decreased after heat treatment indicating degradation of uronic acids present in hemicelluloses. Chemical modifications of wood components were determined by CP/MAS C-13 NMR analysis. Spectra indicated significant degradation of hemicelluloses. Increase of treatment duration resulted in the appearance of new signals, particularly obvious on spectra of samples treated for 15 h, attributed to carbonaceous materials involved in char formation.

This paper deals with the methods used at Snecma (SAFRAN Group) to simulate the real mistuned dynamic behavior of bladed disks. Many applications of the method on industrial cases are also presented. The dissymmetry of a real bladed disk, which is mainly generated by small deviations in its geometry, leads to different dynamic impedances of the blades. These variations in impedance cause significant amplification of the forced response of the bladed disk. We propose to focus on industrial methods that can be used to simulate the mistuned dynamic behavior of a bladed disk in the case of small “frequency mistuning” or of greater “large mistuning”. This method, based on the modal synthesis technique (Benfield and Hruda family), can be classified as a “first generation method”. The first originality of this method consists in taking into account major mistuning, such as that induced by an FOD event. A second innovation concerns the use of these methods to assess in probabilistic terms the correction factor to apply to the maximum dynamic level measured during engine certification tests. The first part of the paper relates to the proposed method and its validation for large-scale “shape” mistuning on an academic test case. In the second section, we present a number of industrial applications: • An application of “geometric mistuning” is presented on a bladed disk after an FOD event. The same kind of analysis as previously described is carried out and the numerical results are commented. • The mistuning analyses are carried out on an industrial blisk with a local defect. The sensitivity of the response amplification factor is calculated versus the mistuning rate using a probabilistic approach. • Another application of the mistuning strategy is discussed: it concerns the use of the mistuning method to specify the correction factor of partial dynamic strain gauge measurements in order to assess the maximum level of a bladed disk. • The last application is dedicated to the simulation of intentional mistuning to increase the aeroelastic stability of an industrial test case.Copyright © 2006 by ASME

A new poly(paraphenylene) recently obtained by electropolymerization of dihalobenzene is described in terms of infra-red and UV-visible absorptions, electron paramagnetic resonance, DC conductivity of the pristine material. The first data on ASF5 doping are given. The properties of the electropolymer are compared to those of other poly(paraphenylene) synthesized by chemical methods.

Raman scattering results on polyparaphenylene samples prepared by two different methods are presented. The best spectra are obtained with an excitation wavelength in the U.V. range and the Raman bands are peaked at 1216 cm-1, 1276 cm-1 and 1598 cm-1 for λL = 334.8 nm. A comparison with Raman spectra induced by oligomers leads to a correlation between the intensity of the Raman band at ≈ 1220 cm-1 and the number of phenyl rings present in the studied material.

Kinetics of AsF5 doping on polyparaphenylene (PPP) powder synthesized by the Kovacic method (1) were carried out for different pressures and different temperatures. The results are explained in terms of physical adsorption on the high specific area of PPP and diffusion of ASF5 into PPP fibrils. Undoped regions and doped ones are seen by X-ray analysis depending on the doping level.

The fibrous morphology and the crystalline structure of the fibres polyparaphenylene (PPP) are observed by electron microscopy and a comparison is made between the undoped and the doped material.

The results of in situ spectroelectrochemical experiments on thin transparent films of poly( para phenylene) are presented in both oxidation and reduction domains. For reduction, the observed absorptions in the infrared and visible ranges account well for the theoretical predictions. In oxidation, even for a dilute doping level, our data lead to the conclusion that bipolarons are the only gap states involved in the process. Comparisons are established with other published data and theoretical calculations.

Polyparaphenylene, PPP, has been polymerized from benzene, as described by Kovacic, and heavily doped in ASF5 vapour. The spin susceptibilities were about 10−6 emu/mole carbon for the Pauli part, plus one Curie spin per 1000 carbon atoms. The asymmetry of the EPR signal of pellets was found to be in good agreement with Dyson's theoretical predictions for slowly diffusive spins in the case of aged samples. On the other hand, the occurence of exchange interactions gave rise in freshly doped samples to enhanced magnetization diffusion rates, and then to more asymmetrical EPR lines.

Amorphous silicon based thin film transistors for the driving of liquid crystal displays have been fabricated in a very simple way with only 2 photolithographic steps. The process for TFT and matrix elaboration are explained. The transistor electrical characteristics are shown to be compatible with LCD working conditions.

A vibrational study of poly-p-phenylene (PPP) prepared by the Kovacic method is presented. A comparison is made between the vibrational features (in both IR and Raman) of undoped PPP, PPP chemically doped using AsF5 or electrochemically doped with AsF6 −, and finally dedoped by a thermal treatment. In the last case, using the exciting wavelength ΛL = 647.1 nm, additional modes are observed in the Raman spectra (460 cm−1, 920 cm−1 and 1700 cm−1). In AsF5 doped PPP, the IR absorption spectrum reveals also new modes (1552 cm−1, 1273 cm−1 and 1184 cm−1). These features are discussed in the basis of a vibrational model.

In recent years, ride-hailing services (RHSs) have become increasingly popular, serving millions of users per day. Such systems, however, raise significant privacy concerns, because service providers are able to track the precise mobility patterns of all riders and drivers. In this paper, we propose ORide (Oblivious Ride), a privacy-preserving RHS based on somewhat-homomorphic encryption with optimizations such as ciphertext packing and transformed processing. With ORide, a service provider can support the matching of riders and drivers without learning their identities or location infor- mation. ORide offers riders with fairly large anonymity sets (e.g., several thousands), even in sparsely-populated areas. In addition, ORide supports key RHSs features such as easy payment, reputation scores, accountability, and retrieval of lost items. Using real data-sets consisting of millions of rides, we show that the computational and network overhead introduced by ORide is acceptable. For example, ORide only adds several milliseconds to ride-hailing operations and the extra driving distance for a driver is less than 0.5 km in more than 75% of the cases evaluated. In short, we show that a RHS can offer strong privacy guarantees to both riders and drivers while maintaining the convenience of its services.