Occupational, academic, and personal determinants of wellbeing and psychological distress in residents: results of a survey in Lyon, France.

Introduction: The mental health of residents is a growing significant concern, particularly with respect to hospital and university training conditions. Our goal was to assess the professional, academic, and psychological determinants of the mental health status of all residents of the academy of Lyon, France. Materials and methods: The Health Barometer of Lyon Subdivision Residents (BASIL) is an initiative which consists in proposing a recurrent online survey to all residents in medicine, pharmacy, and dentistry, belonging to the Lyon subdivision. The first of these surveys was conducted from May to July 2022. Participants should complete a series of validated questionnaires, including the Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS), and the Kessler Psychological Distress Scale (K6), respectively, and ad-hoc questions assessing their global health and hospital and academic working conditions. A Directed Acyclic Graph (DAG) analysis was conducted prior to multivariable analyses, to explore the determinants associated with low wellbeing (WEMWBS <43) and high psychological distress (K6 ≥ 13). Results: A total of 904 residents (response rate: 46.7%) participated in the survey. A low level of wellbeing was observed in 23% of participants, and was significantly associated to job strain (OR = 2.18; 95%CI = [1.32-3.60]), low social support (OR = 3.13; 95%CI = [2.05-4.78]) and the experience of very poor university teaching (OR = 2.51; 95%CI = [1.29-4.91]). A high level of psychological distress was identified for 13% of participants, and associated with low social support (OR = 2.41; 95%CI = [1.48-3.93]) and the experience of very poor university teaching (OR = 2.89, 95%CI = [1.16-7.21]). Conclusion: Hospital working conditions, social support, and the perception of teaching quality, were three major determinants of wellbeing and psychological distress among health profession residents. Demographic determinants, personal life and lifestyle habits were also associated. This supports a multilevel action in prevention programs aiming to enhance wellbeing and reduce mental distress in this specific population and local organizational specificities.

Flexible implementation of modulated localisation microscopy based on DMD.

Localisation microscopy of individual molecules allows one to bypass the diffraction limit, revealing cellular organisation on a nanometric scale. This method, which relies on spatial analysis of the signal emitted by molecules, is often limited to the observation of biological objects at shallow depths, or with very few aberrations. The introduction of a temporal parameter into the localisation process through a time-modulated excitation was recently proposed to address these limitations. This method, called ModLoc, is demonstrated here with an alternative flexible strategy. In this implementation, to encode the time-modulated excitation a digital micromirror device (DMD) is used in combination with a fast demodulation approach, and provides a twofold enhancement in localisation precision. Layout: Nowadays, we can use an optical microscope to observe how proteins are organised in 3D within a cell at the nanoscale. By carefully controlling the emission of molecules in both space and time, we can overcome the limitations set by the diffraction limit. This allows us to pinpoint the exact location of molecules more precisely. However, the usual spatial analysis method limits observations to shallow depths or causing low distortion of optical waves. To overcome these restrictions, a recent approach introduces a temporal element to the localisation process. This involves changing the illumination over time to enhance the precision of localisation. This method, known as ModLoc, is showcased here using a flexible and alternative strategy. In this setup, a matrix of micrometric mirrors, working together with a fast demodulation optical module, is used to encode and decode the time-modulated information. This combination results in a twofold improvement in localisation precision.

[The impact of lockdown on mental health in PhD students, a cohort study in a French university]. / Impact du confinement sur la santé mentale des doctorants, une étude de cohorte dans une université française.

INTRODUCTION: Few studies are available on the health status of doctoral students. This position at the border between university studies and a professional activity presents specific risk factors, especially in terms of psychosocial constraints. The lockdowns implemented worldwide to control the COVID-19 pandemic are potentially worsening factors. METHODS: At Lyon 1 University, a systematic medical follow-up of first year PhD students had been set up by the occupational health service in 2019. In the context of the lockdown during the COVID-19 pandemic, a telephonic interview was proposed to the same PhD students in order to assess the impact of the lockdown on working conditions and health and to provide possible assistance. During this interview, a standardized questionnaire was used to collect information about the conditions during the lockdown, doctoral work during this period and the consequences on research progress, as well as possible financial difficulties due to the lockdown. In addition, questions were asked about the perceived general health conditions and consultation with a health practitioner during this period. The Patient Health Questionnaire (PHQ-9) and the Generalized Anxiety Disorder (GAD-7) were used to assess depression and anxiety. Questions on lifestyle during lockdown, changes in diet during the period, weight change, and changes in the quantity and quality of their sleep were also asked. Comparisons of perceived health status, the prevalence of anxiety and depression symptoms at baseline and during the follow-up survey were made by MacNemar Chi2 tests, as the data were repeated ones. The students were informed orally and in writing that their data would be entered anonymously into a computer and that they could have access to their data in accordance with the General Data Protection Regulation (GDPR). They were all informed by e-mail about the study results at the end of the study. The data collection process was registered with the National Institute for Health Data (INDS) and with the university's register under reference no. 2020/002 by the university's data protection officer in compliance with the French data protection laws (CNIL). The protocol was approved by the ethics committee of the Lyon University College of General Medicine (notification number: 2020-10-29-02). RESULTS: Of the 161 PhD students initially interviewed, 149 underwent a second interview. In total, 89.2% of the students assessed their health as good or very good. Regarding the answers to the GAD-7 questionnaire, 8.1% had a score equal to or higher than 10, corresponding to moderate to severe anxiety. Regarding the answers to PHQ-9, 19.6% of the PhD students had a score equal to or higher than 9 corresponding to moderate to severe depressive syndromes. The prevalence of an anxiety disorder was significantly associated with the absence of an outside private access in the place of residence during lockdown (75% vs. 37%), an increase in coffee consumption (33% vs. 5%), an increase in the quantity of food consumed (50% vs. 12%), weight gain (50% vs. 19%) and a deterioration in sleep quality (75% vs. 28%). The prevalence of a depressive symptom was significantly associated with lockdown in an urban area (89% vs. 70%), the occurrence of financial difficulties (7% vs. 1%), the consultation of a health professional during the period (34% vs. 15%), smoking cessation (14% vs. 1%), changes in the quantity (31% vs. 9%) and deterioration (59% vs. 25%) of the quality of sleep, and diet changes (66% vs. 43%). GAD-7 scores were unchanged for 90% of participants between the two surveys, but they were higher for 6.8% of doctoral students and lower for 2.7 % (P=0.1). A deterioration of the PHQ-9 scores, i.e. higher scores in the second survey compared to the first, was observed for 15.5% of the PhD students while an improvement of the scores was observed for 1.4% (P=0.0001). DISCUSSION: A number of studies have been published on the impact of lockdown on mental health, but few of them focused specifically on PhD students and even fewer were prospective studies. Their results are therefore difficult to compare with ours; they generally show GAD-7 and PHQ-9 scores that are similar to those of our population, or even higher. The impact of lockdown on the mental health of doctoral students highlighted in our study therefore justifies an appropriate follow-up of this population, particularly in the case of former psychiatric disorders.

Damping-Driven Time Reversal for Waves.

Damping is usually associated with irreversibility. Here, we present a counterintuitive concept to achieve time reversal of waves propagating in a lossless medium using a transitory dissipation pulse. Applying a sudden and strong damping in a limited time generates a time-reversed wave. In the limit of a high damping shock, this amounts to "freezing" the initial wave by maintaining the wave amplitude while canceling its time derivative. The initial wave then splits in two counterpropagating waves with half of its amplitude and time evolutions in opposite directions. We implement this damping-based time reversal using phonon waves propagating in a lattice of interacting magnets placed on an air cushion. We show with computer simulations that this concept also applies to broadband time reversal in complex disordered systems.

Incidence of commuting accidents among non-physician staff in a large French university hospital centre from 2012 to 2016.

BACKGROUND: Traffic road crashes are the leading cause of fatal crashes at work. The circumstances of work-related road accidents have been a regular focus of study, but there is still a lack of knowledge about commuting accidents. OBJECTIVE: The aims of this study were to estimate the overall incidence of commuting accidents for non-physician professionals in a major French university hospital, by gender and different professional categories, and to assess its evolution over a 5-year period. METHODS: A descriptive analysis was performed on 390 commuting accidents from 2012 to 2016 extracted from the university hospital's occupational health service. Incidences of commuting accidents were calculated according to gender, occupational categories, and years. Crude relative risk (RR) for the association of commuting accidents with gender, occupational categories, and year of the accident was also estimated using log-binomial regressions. RESULTS: The annual incidence ranged from 354 to 581 accidents per 100,000 employees. Compared with administrative staff, the relative risk (RR) for commuting accidents for service agents was 1.6 (95% confidence interval (CI): 1.1-2.4) and for auxiliary nurses and childcare assistants was 1.3 (95% CI: 1.0-1.9). Nursing executives had a non-significantly lower RR of 0.6 (95% CI: 0.3-1.5). CONCLUSION: The increased risk observed for the auxiliary nurses and childcare assistants and for the service agents may be related in part to the fatigue caused by work schedules, long commuting distances, physical work, and psychological burden.

Comprehensive refractive manipulation of water waves using electrostriction.

The control of wave propagation based on refraction principles offers unparalleled possibilities as shown by the striking example of optics. This approach is unfortunately limited for water waves as it relies mainly on variations of the liquid depth which, while controlling the wave velocity, also trigger nonlinearities and damping. In this article, we show experimentally that electrostriction allows to implement extensive refraction-based control of water waves in a precise and contactless manner. The setup consists of an electrode under high voltage placed above the grounded conductive water. The waves propagating under the electrode can be slowed down up to approximately half their speed compared to free propagation. We characterize the Snell-Descartes laws of refraction and the total internal reflection for the water waves. We implement emblematic refraction-based devices such as electrically tunable focusing lenses, waveguides without obstacles, and beam splitters based on frustrated internal reflection to perform interference experiments.

Changes in the European Union definition for endocrine disruptors: how many molecules remain a cause for concern? The example of crop protection products used in agriculture in France in the six last decades.

Background: The endocrine-disrupting effects of phytopharmaceutical active substances (PAS) on human health are a public health concern. The CIPATOX-PE database, created in 2018, listed the PAS authorized in France between 1961 and 2014 presenting endocrine-disrupting effects for humans according to data from official international organizations. Since the creation of CIPATOX-PE, European regulations have changed, and new initiatives identifying substances with endocrine-disrupting effects have been implemented and new PAS have been licensed. Objectives: The study aimed to update the CIPATOX-PE database by considering new 2018 European endocrine-disrupting effect identification criteria as well as the new PAS authorized on the market in France since 2015. Methods: The endocrine-disrupting effect assessment of PAS from five international governmental and non-governmental initiatives was reviewed, and levels of evidence were retained by these initiatives for eighteen endocrine target organs. Results: The synthesis of the identified endocrine-disrupting effects allowed to assign an endocrine-disrupting effect level of concern for 241 PAS among 980 authorized in France between 1961 and 2021. Thus, according to the updated CIPATOX-PE data, 44 PAS (18.3%) had an endocrine-disrupting effect classified as "high concern," 133 PAS (55.2%) "concern," and 64 PAS (26.6%) "unknown effect" in the current state of knowledge. In the study, 42 PAS with an endocrine-disrupting effect of "high concern" are similarly classified in CIPATOX-PE-2018 and 2021, and 2 new PAS were identified as having an endocrine-disrupting effect of "high concern" in the update, and both were previously classified with an endocrine-disrupting effect of "concern" in CIPATOX-PE-2018. Finally, a PAS was identified as having an endocrine-disrupting effect of "high concern" in CIPATOX-PE-2018 but is now classified as a PAS not investigated for endocrine-disrupting effects in CIPATOX-PE-2021. The endocrine target organs associated with the largest number of PAS with an endocrine-disrupting effect of "high concern" is the reproductive system with 31 PAS. This is followed by the thyroid with 25 PAS and the hypothalamic-pituitary axis (excluding the gonadotropic axis) with 5 PAS. Discussion: The proposed endocrine-disrupting effect indicator, which is not a regulatory classification, can be used as an epidemiological tool for occupational risks and surveillance.

Role of the occupational disease consultant in the multidisciplinary discussion of interstitial lung diseases.

BACKGROUND: Diffuse interstitial lung diseases (ILD) constitute a heterogeneous group of conditions with complex etiological diagnoses requiring a multidisciplinary approach. Much is still unknown about them, particularly their relationship with occupational exposures. The primary objective of this study was to investigate the distribution of occupational exposures according to type of ILD. The secondary objectives were to estimate the proportion of ILDs possibly related to occupational exposure and to evaluate the added value of the participation of an occupational disease consultant in ILD multidisciplinary discussions (MDD). METHODS: From May to December 2020, all consecutive patients with ILD whose cases were reviewed during a MDD in a referral centre for ILD were prospectively offered a consultation with an occupational disease consultant. RESULTS: Of the 156 patients with ILD whose cases were reviewed in MDD during the study period, 141 patients attended an occupational exposure consultation. Occupational exposure was identified in 97 patients. Occupational exposure to asbestos was found in 12/31 (38.7%) patients with idiopathic pulmonary fibrosis (IPF) and in 9/18 (50.0%) patients with unclassifiable fibrosis. Occupational exposure to metal dust was found in 13/31 (41.9%) patients with IPFs and 10/18 (55.6%) patients with unclassifiable fibrosis. Silica exposure was found in 12/50 (24.0%) patients with autoimmune ILD. The link between occupational exposure and ILD was confirmed for 41 patients after the specialist occupational consultation. The occupational origin had not been considered (n = 9) or had been excluded or neglected (n = 4) by the MDD before the specialised consultation. A total of 24 (17%) patients were advised to apply for occupational disease compensation, including 22 (15.6%) following the consultation. In addition, a diagnosis different from the one proposed by the MDD was proposed for 18/141 (12.8%) patients. CONCLUSIONS: In our study, we found a high prevalence of occupational respiratory exposure with a potential causal link in patients with ILD. We suggest that a systematic specialised consultation in occupational medicine could be beneficial in the ILD diagnostic approach.

Underreporting of occupational blood and body fluid exposure in French university hospitals in 2017.

BACKGROUND: Occupational blood and body fluid exposures (OBBFEs) are one of the biological risks run by health professionals, especially in hospitals. OBJECTIVE: The objectives of this study were to assess the occurrence and reporting of occupational blood and body fluid exposures (OBBFEs) in university hospital medical staff and to investigate factors associated to declared OBBFE and factors associated to reported OBBFE. METHODS: A self-administered questionnaire has been e-mailed to all junior and senior medical staff in four university hospital centers in one administrative region of France in 2017. RESULTS: 292 of the 1,228 respondents declared at least one OBBFE. More than two-thirds (70.2%) were under-reporters and more than half (53.8%) non-reporters. Younger subjects, surgical specialties and other associated work accidents were risk factors for OBBFE. Considering the reporting procedure too complex was a risk factor for underreporting. CONCLUSIONS: Underreporting by hospital medical staff was a persistent phenomenon, with a high rate. The OBBFE reporting procedure needs rethinking.

Mental health and working constraints of first-year PhD students in health and science in a French university: a cross-sectional study in the context of occupational health monitoring.

OBJECTIVES: To assess the mental health and working constraints perception of first-year PhD in France. DESIGN: It is a cross-sectional study. SETTING: The study was conducted by the team of the Lyon 1 University's Occupational Health and Medical Service for Staff, from October 2019 to February 2020. First-year PhD students employed by the university were seen during the routine occupational health medical check-up. PARTICIPANTS: A total of 161 PhD students in science from the 2019 intake were included in the study (participation rate 98%). OUTCOME MEASURES: Data were collected using a self-questionnaire on psychosocial constraints at work (Job Content Questionnaire), the quality of the professional relationship with the supervisor (Advisory Working Alliance Inventory, Student perspective (AWAI-S)), medical conditions, anxiety (Generalized Anxiety Disorder-7) and depressive symptoms (Patient Health Questionnaire-9). RESULTS: A total of 161 PhD students from the 2019 intake were included in the study (participation rate 98%). Most of the PhD students reported high psychological demands (58%), high decision latitude (53%), high social support (55%) and good professional relationships with their supervisor (mean of global score of AWAI-S=114.5). However, 34% showed signs of at least mild depression, 19% showed signs of anxiety and 20% were referred to a mental health professional after the survey. Bivariate analyses showed that history of psychiatric disorders, their relationship with their supervisor, having complementary teaching activities and stressful working conditions contributed to anxiety and depression. CONCLUSIONS: Even in the first year of their PhD, some students had mental health issues. It seems relevant to generalise the medical follow-up of all PhD students as soon as they enter the doctoral programme in order to detect and treat their health problems and psychological disorders at an early stage.

Frequency of Asbestos Exposure and Histological Subtype of Ovarian Carcinoma.

The International Agency for Research on Cancer established a causal link between asbestos exposure and ovarian cancer. However, the exposure frequency and histological characteristics of asbestos-associated ovarian cancers remain to be investigated in detail. This multicenter case-case study assessed the asbestos exposure in ovarian carcinoma (OC) patients, alongside its association with histological subtype. Women were recruited in four hospitals in Lyon, France. Histological reports were reviewed by a pathologist. Patient and family members' data were collected by phone-based questionnaires. Asbestos exposure was defined as direct (occupational and environmental) and indirect (via parents, partners, and children). An industrial hygienist assessed the probability and level of exposure. The 254 enrolled patients (mean age 60 years) reported having an average of 2.3 different jobs (mean working duration 29 years). The prevalence of direct and indirect asbestos exposure was 13% (mean exposure duration 11 years) and 46%, respectively. High-grade serous carcinoma accounted for 73% of all OCs and 82% of histological subtypes in women with direct exposure. After adjustment on a familial history of OC, no significant associations between asbestos exposure (direct and/or indirect) and high-grade serous carcinoma were found. Women with OC had a high prevalence of asbestos exposure. Establishing risk profiles, as reported here, is important in facilitating compensation for asbestos-related OCs and for the surveillance of women at risk.

COVID-19 Health Crisis Workloads and Screening for Psychological Impact in Nursing Home Staff: A Qualitative and Quantitative Survey.

Background: Nursing homes were particularly affected by the COVID-19 pandemic. The purpose of this study was to evaluate qualitatively and quantitatively with the use of a self-reported questionnaire as a tool for screening for mental disorders in nursing home staff. Methods: A multicenter epidemiological study was conducted in 12 nursing homes in France with 1117 nursing home staff eligible. Socio-demographic, occupational, and medical data were collected by anonymous self-reported questionnaire using validated scales to assess anxiety/depressive symptoms (HAD scale) and post-traumatic stress disorder (PCL-5). A total of 12 semi-structured interviews were conducted to assess acceptance and expectations for the use of the questionnaire. Results: The participation rate was 34.5%. Data from 373 questionnaires were included in the analysis. The questionnaire was well accepted by the participants and met their wishes for prevention action. The sample was 82% female. More than half reported a feeling of powerlessness and lack of time or staffing. The prevalence of anxiety symptoms was 22%, depressive symptoms 10%, and post-traumatic stress 7%. Conclusions: This study underlines the interest in screening for mental disorders by self-reported questionnaire and deploying preventive actions in the workplace to reduce stress and facilitate the reconciliation of family and working life in this context of the pandemic.

Experimental Implementation of Wave Propagation in Disordered Time-Varying Media.

Here, we study and implement the temporal analog in time disordered sytems. A spatially homogeneous medium is endowed with a time structure composed of randomly distributed temporal interfaces. This is achieved through electrostriction between water surface and an electrode. The wave field observed is the result of the interferences between reflected and refracted waves on the interfaces. Although no eigenmode can be associated with the wave field, several common features between space and time emerge. The waves grow exponentially depending on the disorder level in agreement with a 2D matrix evolution model such as in the spatial case. The relative position of the momentum gap appearing in the time modulated systems plays a central role in the wave field evolution. When tuning the excitation to compensate for the damping, transient waves, localized in time, appear on the liquid surface. They result from a particular history of the multiple interferences produced by a specific sequence of time boundaries.

Frequency Conversion Cascade by Crossing Multiple Space and Time Interfaces.

Time varying media recently emerged as promising candidates to fulfill the dream of controlling the wave frequency without nonlinear effects. However, frequency conversion remains limited by the dynamics of the variations of the propagation properties. Here we propose a new concept of space-time cascade to achieve arbitrary large frequency shifts by iterated elementary transformation steps. These steps use an intermediate medium in which wave packets enter and exit through noncommutative space and time interfaces. This concept avoids high frequency or subwavelength demanding metamaterials. Upward and downward frequency conversions are performed. The transmitted energy yield is given by the frequency ratio, regardless of impedence mismatch. We implement this concept with water waves controlled by electrostriction and achieve frequency conversion over 4 octaves.

Time-modulated excitation for enhanced single-molecule localization microscopy.

Structured illumination in single-molecule localization microscopy provides new information on the position of molecules and thus improves the localization precision compared to standard localization methods. Here, we used a time-shifted sinusoidal excitation pattern to modulate the fluorescence signal of the molecules whose position information is carried by the phase and recovered by synchronous demodulation. We designed two flexible fast demodulation systems located upstream of the camera, allowing us to overcome the limiting camera acquisition frequency and thus to maximize the collection of photons in the demodulation process. The temporally modulated fluorescence signal was then sampled synchronously on the same image, repeatedly during acquisition. This microscopy, called ModLoc, allows us to experimentally improve the localization precision by a factor of 2.4 in one direction, compared to classical Gaussian fitting methods. A temporal study and an experimental demonstration both show that the short lifetimes of the molecules in blinking regimes impose a modulation frequency in the kilohertz range, which is beyond the reach of current cameras. A demodulation system operating at these frequencies would thus be necessary to take full advantage of this new localization approach. This article is part of the Theo Murphy meeting issue 'Super-resolution structured illumination microscopy (part 2)'.

Liquid walls and interfaces in arbitrary directions stabilized by vibrations.

Gravity shapes liquids and plays a crucial role in their internal balance. Creating new equilibrium configurations irrespective of the presence of a gravitational field is challenging with applications on Earth as well as in zero-gravity environments. Vibrations are known to alter the shape of liquid interfaces and also to change internal dynamics and stability in depth. Here, we show that vibrations can also create an "artificial gravity" in any direction. We demonstrate that a liquid can maintain an inclined interface when shaken in an arbitrary direction. A necessary condition for the equilibrium to occur is the existence of a velocity gradient determined by dynamical boundary conditions. However, the no-slip boundary condition and incompressibility can perturb the required velocity profile, leading to a destabilization of the equilibrium. We show that liquid layers provide a solution, and liquid walls of several centimeters in height can thus be stabilized. We show that the buoyancy equilibrium is not affected by the forcing.

Medicine consumptions and occupational road risk.

BACKGROUND: Whereas an increased risk of road traffic crashes has been highlighted as linked to some medicine consumptions, there is no available data on this risk according to the type of journey (private, commuting or mission). Drivers on occupational journey (commuting or mission) are likely to have different coping behaviors related to the use of medicines than drivers on private journey. The aim of our study was to investigate the association between exposure to ten classes of medicines and the risk of being responsible for a road traffic crash according to the type of journey (private, commuting or mission). METHODS: The data used came from three French national databases: the national police database of injurious crashes, the police reports and the national health care insurance database. A total of 179,269 drivers aged between 18 and 65 years old involved in an injurious crash in France between July 2005 and December 2015 were included in the analyses. Logistic regression models stratified by journey were used to estimate the Odds Ratios (OR) and 95 % confidence intervals (95 % CI), adjusted for potential confounding factors. RESULTS: Medicines exposure levels were generally lower for drivers during occupational journeys, the risk of being responsible for a road traffic crash seems to be higher on commuting or mission journeys than on private journeys for four medicines. Indeed, for antiepileptics the OR was 1.59 [1.01-2.51] for mission journeys, 1.63 [1.24-2.15] for commuting journeys, and 1.47 [1.25-1.73] for private journey. For psycholeptics the OR was 1.02 [0.80-1.28] for mission journey, 1.19 [1.03-1.39] for commuting and 1.17 [1.08-1.26] for private journey. For psychoanaleptics OR was 1.35 [1.02-1.78] for mission journeys, 1.37 [1.17-1.60] for commuting journeys and 1.26 [1.14-1.40] for private journeys. Finally, for other nervous system drugs OR reached 2.04 [1.35-3.07] for mission journeys compared to 1.43 [1.21-1.70] for private journeys. CONCLUSION: Our results encourage the implementation of preventive measures about some treatments and diseases in the context of occupational journeys.

Author Correction: Floating under a levitating liquid.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Floating under a levitating liquid.

When placed over a less dense medium, a liquid layer will typically collapse downwards if it exceeds a certain size, as gravity acting on the lower liquid interface triggers a destabilizing effect called a Rayleigh-Taylor instability1,2. Of the many methods that have been developed to prevent the liquid from falling3-6, vertical shaking has proved to be efficient and has therefore been studied in detail7-13. Stabilization is the result of the dynamical averaging effect of the oscillating effective gravity. Vibrations of liquids also induce other paradoxical phenomena such as the sinking of air bubbles14-19 or the stabilization of heavy objects in columns of fluid at unexpected heights20. Here we take advantage of the excitation resonance of the supporting air layer to perform experiments with large levitating liquid layers of up to half a litre in volume and up to 20 centimetres in width. Moreover, we predict theoretically and show experimentally that vertical shaking also creates stable buoyancy positions on the lower interface of the liquid, which behave as though the gravitational force were inverted. Bodies can thus float upside down on the lower interface of levitating liquid layers. We use our model to predict the minimum excitation needed to withstand falling of such an inverted floater, which depends on its mass. Experimental observations confirm the possibility of selective falling of heavy bodies. Our findings invite us to rethink all interfacial phenomena in this exotic and counter-intuitive stable configuration.