The number of beds occupied is an independent risk factor for discharge of trauma patients

Reducing the burden of limited capacity on medical practitioners and public health systems requires a time-dependent characterization of hospitalization rates, such that inferences can be drawn about the underlying causes for hospitalization and patient discharge. The aim of this study was to analyze non-medical risk factors that lead to the discharge of trauma patients. This retrospective cohort study includes trauma patients who were treated in Switzerland between 2011 and 2018. The national Swiss database for quality assurance in surgery (AQC) was reviewed for trauma diagnoses according to the ICD-10 code. Non-medical risk factors include seasonal changes, daily changes, holidays, and number of beds occupied by trauma patients across Switzerland. Individual patient information was aggregated into counts per day of total patients, as well as counts per day of levels of each categorical variable of interest. The ARIMA-modeling was utilized to model the number of discharges per day as a function of auto aggressive function of all previously mentioned risk factors. This study includes 226,708 patients, 118,059 male (age 48.18, standard deviation (SD) 22.34 years) and 108,649 female (age 62.57, SD 22.89 years) trauma patients. The mean length of stay was 7.16 (SD 14.84) days and most patients were discharged home (n = 168,582, 74.8%). A weekly and yearly seasonality trend can be observed in admission trends. The mean number of occupied trauma beds ranges from 3700 to 4000 per day. The number of occupied beds increases on weekdays and decreases on holidays. The number of occupied beds is a positive, independent risk factor for discharge in trauma patients; as the number of occupied beds increases at any given time, so does the risk for discharge. The number of beds occupied represents an independent non-medical risk factor for discharge. Capacity determines triage of hospitalized patients and therefore might increase the risk of premature discharge

A new method of probing mechanical losses of coatings at cryogenic temperatures

A new method of probing mechanical losses and comparing the corresponding deposition processes of metallic and dielectric coatings in 1-100 MHz frequency range and cryogenic temperatures is presented. The method is based on the use of extremely high-quality quartz acoustic cavities whose internal losses are orders of magnitude lower than any available coatings nowadays. The approach is demonstrated for Chromium, Chromium/Gold and a multilayer tantala/silica coatings. The ${\rm Ta}_2{\rm O}_5/{\rm Si}{\rm O}_2$ coating has been found to exhibit a loss angle lower than $1.6\times10^{-5}$ near 30 {\rm MHz} at 4 {\rm K}. The results are compared to the previous measurements

Refroidir un résonateur mécanique macroscopique proche de son état quantique fondamental

In this work, we attempt the experimental demonstration of quantum effects in the motion of a macroscopic mechanical resonator with a mass of 33 micrograms, about 3 orders of magnitude above the mass of the heaviest system demonstrated so far in the quantum ground state. We have designed, fabricated, and operated an optomechanical resonator at 3.6 MHz, with an optical finesse of 100,000 and a mechanical quality factor near 100 million, embedded in the 100 mK environment of a dilution refrigerator. We present a fully automatized optical measurement setup, including a filter cavity, a homodyne detector, and various feedback controllers implemented in an FPGA with the custom-developed software PyRPL. We have laser-cooled the compression mode of our mechanical resonator to a mean thermal occupation number of 20 phonons. Cooling is limited by the onset of an optomechanical instability of suspension modes with frequencies below 100 kHz. A custom-tailored digital filter to suppress this instability has enabled us to reach a regime where quantum backaction amounts to about 30 % of the total force noise on the mechanical resonator. For even higher ratios in the future, we present the design of a phononic-crystal input mirror with a reduced Brownian motion displacement noise floor.Ce travail s'attaque à la mise en évidence expérimentale d'effets quantiques dans le mouvement d'un résonateur mécanique macroscopique avec une masse effective de 33 microgrammes, soit 3 ordres de grandeur au-dessus de celle du système mécanique le plus massif observé à ce jour dans son état quantique fondamental. Nous avons conçu, fabriqué et fait fonctionner un résonateur optomécanique à 3,6 MHz avec une finesse optique de 100.000 et un facteur de qualité mécanique proche de 100 millions, inséré dans l'environnement à 100 mK d'un réfrigérateur à dilution. Nous présentons un montage optique complètement automatisé incluant une cavité de filtrage, une détection homodyne et plusieurs asservissements, implémentés dans un FPGA avec le programme PyRPL développé spécifiquement pour cette expérience. Nous avons refroidi par laser le mode de compression de notre résonateur mécanique jusqu'à un nombre moyen d'occupation thermique de 20 phonons. Le refroidissement est limité par l'apparition d'une instabilité optomécanique de plusieurs modes des suspensions, au-dessous de 100 kHz. Un filtre digital particulier pour supprimer cette instabilité nous a permis d'atteindre le régime où l'action en retour quantique contribue à hauteur d'environ 30 % au bruit de force total de l'oscillateur mécanique. Pour atteindre des contributions encore plus importantes à l'avenir, nous présentons la conception d'un miroir d'entrée à cristal phononique, caractérisé par un plancher de bruit de mouvement Brownien réduit

Red Pitaya DAC performance

<p>The RedPitaya fast analog outputs have a noise level of the order of the 3-4 least significant bits. This noise is correlated with the switching of digital signals on the board, notably switching of the digital output signal itself, which leads to a nonmonotonic DAC performance. With a tiny modification of the board, this problem can be removed: DAC’s are nicely monotonic and noise performance improves so that the outputs have about 13 <a href="https://en.wikipedia.org/wiki/Effective_number_of_bits">ENOB</a>s.</p

Adding voltage regulators for the RedPitaya output stage

The current V1.1 RedPitaya board lacks the voltage regulators for the analog output circuit which causes a number of problems such as nonmonotonic DACs, excess noise and crosstalk. We describe to to equip a board with those regulators. <br

Cryogenic optomechanic cavity in low mechanical loss material

International audienceMechanical losses lower than 10−9 have been demonstrated on quartz crystal acoustic cavities at liquid helium temperature. In addition, such cavities could rather easily be adapted to be used as optical cavities. This paper addresses the optomechanic devices that could merge from, while highlighting the major assets of each option and showing some preliminary results, including tests on quartz and CaF2 samples. It is shown that the mechanical displacement can be actuated optically by radiation pressure according to proper designs

Optomechanical coupling in a quartz crystal resonator for cryogenic clocks

International audiencePlano-convex quartz crystal resonators can exhibit quality-factors close to a billion at 4K. They are also suitable to operate as optical cavities. As a consequence they are good candidates for optomechanic experiments including quartz-based cryogenic clocks. The paper is focused on the latter application and demonstrates its feasability

Impact of Coatings on the Quality Factor of a Quartz Crystal Resonator at Liquid Helium Temperature

International audienceEffects of coatings on the quality factor of quartz crystal resonators operating at liquid helium temperature are analyzed. A first set of tests demonstrates the effects of gold and chromium electrodes at low temperature. The second set of tests involves a multilayer tantala/silica coating used to reach an extreme reflectance on mirrors such those used in optical cavities or Michelson interferometers. Mechanical losses are measured and discussed from the theoretical model the most frequently used