OBJECTIVES:High-flow nasal cannula is increasingly used in the management of respiratory failure. However, little is known about its impact on respiratory effort, which could explain part of the ...benefits in terms of comfort and efficiency. This study was designed to assess the effects of high-flow nasal cannula on indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min) in adults.
DESIGN:A randomized controlled crossover study was conducted in 12 patients with moderate respiratory distress (i.e., after partial recovery from an acute episode, allowing physiologic measurements).
SETTING:Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada.
SUBJECTS:Twelve adult patients with respiratory distress symptoms were enrolled in this study.
INTERVENTIONS:Four experimental conditions were evaluatedbaseline with conventional oxygen therapy and high-flow nasal cannula at 20, 40, and 60 L/min. The primary outcomes were the indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min). Secondary outcomes included tidal volume, respiratory rate, minute volume, dynamic lung compliance, inspiratory resistance, and blood gases.
MEASUREMENTS AND MAIN RESULTS:Esophageal pressure variations decreased from 9.8 (5.8–14.6) cm H2O at baseline to 4.9 (2.1–9.1) cm H2O at 60 L/min (p = 0.035). Esophageal pressure-time product/min decreased from 165 (126–179) to 72 (54–137) cm H2O • s/min, respectively (p = 0.033). Work of breathing/min decreased from 4.3 (3.5–6.3) to 2.1 (1.5–5.0) J/min, respectively (p = 0.031). Respiratory pattern variables and capillary blood gases were not significantly modified between experimental conditions. Dynamic lung compliance increased from 38 (24–64) mL/cm H2O at baseline to 59 (43–175) mL/cm H2O at 60 L/min (p = 0.007), and inspiratory resistance decreased from 9.6 (5.5–13.4) to 5.0 (1.0–9.1) cm H2O/L/s, respectively (p = 0.07).
CONCLUSIONS:High-flow nasal cannula, when set at 60 L/min, significantly reduces the indexes of respiratory effort in adult patients recovering from acute respiratory failure. This effect is associated with an improvement in respiratory mechanics.
One of the shortest and most efficient routes toward a series of functionalized pentahelicenes is reported. Benzylic (dibromo)methine coupling is an important entry into functional helicene ...chemistry. It allowed a mono- or a double functionalization by some metal-catalyzed Ar−C, Ar−S, Ar−CN, and Ar−I bond formations. Those functions offer new avenues for further applications. For instance, helicene (4) can be supported on a Ag(001) surface, which was characterized by high-resolution NC-AFM imaging.
Kiruna-type iron oxide−apatite (IOA) deposits constitute an important source of iron and phosphorus, and potentially of rare earth elements (REE). However, the origin of IOA deposits is still a ...matter of debate with models that range from a purely magmatic origin by liquid immiscibility to replacement of host rocks by hydrothermal fluids from different sources. In order to better constrain the origin of Andean IOA deposits, we focused on the Cretaceous Cerro Negro Norte deposit located in the Chilean Iron Belt, northern Chile. The Cerro Negro Norte magnetite ore is hosted in andesitic rocks and is spatially and genetically associated with a diorite intrusion. Our results show that the deposit is characterized by three main mineralization/alteration episodes: an early Fe–oxide event with magnetite and actinolite followed by four stages that comprise the main hydrothermal event (hydrothermal magnetite + actinolite; calcic–sodic alteration + sulfides; quartz–tourmaline and propylitic alteration) and a minor supergene event. Based on textural and chemical characteristics, four different types of magnetite are recognized at Cerro Negro Norte: type I, represented by high-temperature (~ 500 °C) magnetite cores with amphibole, pyroxene, and minor Ti–Fe oxide inclusions; type II, an inclusion-free magnetite, usually surrounding type I magnetite cores; type III corresponds to an inclusion-free magnetite with chemical zoning formed under moderate temperatures; and type IV magnetite contains abundant inclusions and is related to low-temperature (~ 250 °C) hydrothermal veinlets. Electron probe and laser ablation ICP-MS analyses of the four magnetite types show that the incorporation of Al, Mn, Ti, and V into the magnetite structure is controlled by temperature. Vanadium and Ga concentrations are relatively constant within each magnetite type, but are statistically different among magnetite types, suggesting that both elements could be used to discriminate between magmatic and hydrothermal magnetite. However, our results show that the use of elemental discrimination diagrams should be coupled with detailed textural studies in order to identify superimposed metasomatic events and evaluate the impact of inclusions on the interpretation of microanalytical data. The presence of a distinct textural and chemical variation between magnetite types in Cerro Negro Norte is explained by a transition from high- to low-temperature magmatic-hydrothermal conditions. The microanalytical data of magnetite presented here, coupled with new δ
34
S data for pyrite (− 0.5 to + 4.3‰) and U–Pb ages of the diorite (129.6 ± 1.0 Ma), are indicative of a genetic connection between the diorite intrusion and the magnetite mineralization, supporting a magmatic-hydrothermal flotation model to explain the origin of Kiruna-type deposits in the Coastal Cordillera of northern Chile.
This study examined the effects of video feedback on the nonverbal behavior of handball coaches, and athletes’ and coaches’ anxieties and perceptions. One intervention group (49 participants) and one ...control group (63 participants) completed the Coaching Behavior Assessment System, Coaching Behavior Questionnaire, and Competitive State Anxiety Inventory-2 on two separate occasions, with 7 weeks of elapsed time between each administration. Coaches in the intervention condition received video feedback and a frequency table with a comparison of their personal answers and their team’s answers on the CB AS. Repeated-measures ANOVAs showed that over time, athletes in the intervention group reported significantly less anxiety and perceived their coaches significantly more positively compared with athletes in the nonintervention condition. Over time, coaches in the intervention group perceived themselves significantly more positively than coaches in the nonintervention condition. Compared with field athletes, goalkeepers were significantly more anxious and perceived their coaches less positively. It is concluded that an intervention using video feedback might have positive effects on anxiety and coach perception and that field athletes and goalkeepers possess different profiles.
Osteogenesis Imperfecta (OI) is an inherited form of bone fragility characterised by impaired synthesis of type I collagen, altered trabecular bone architecture and reduced bone mass. High resolution ...peripheral computed tomography (HR-pQCT) is a powerful method to investigate bone morphology at peripheral sites including the weight-bearing distal tibia. The resulting 3D reconstructions can be used as a basis of micro-finite element (FE) or homogenized finite element (hFE) models for bone strength estimation. The hFE scheme uses homogenized local bone volume fraction (BV/TV) and anisotropy information (fabric) to compute healthy bone strength within a reasonable computation time using fabric-elasticity relationships. However, it is unclear if these relationships quantified previously for healthy controls are valid for trabecular bone from OI patients. Thus, the aim of this study is to investigate fabric-elasticity relationships in OI trabecular bone compared to healthy controls.
In the present study, the morphology of distal tibiae from 50 adults with OI were compared to 120 healthy controls using second generation HR-pQCT. Six cubic regions of interest (ROIs) were selected per individual in a common anatomical region. A first matching between OI and healthy control group was performed by selecting similar individuals to obtain identical mean and median age and sex distribution. It allowed us to perform a first morphometric analysis and compare the outcome with literature. Then, stiffness tensors of the ROIs were computed using μFE and multiple linear regressions were performed with the Zysset-Curnier orthotropic fabric-elasticity model.
An initial fit was performed on both the OI group and the healthy control group using all extracted ROIs. Then, data was filtered according to a fixed threshold for a defined coefficient of variation (CV) assessing ROI heterogeneity and additional linear regressions were performed on these filtered data sets. These full and filtered data were in turn compared with previous results from μCT reconstructions obtained in other anatomical locations. Finally, the ROIs of both groups were matched according to their BV/TV and degree of anisotropy (DA). Linear regressions were performed using these matched data to detect statistical differences between the two groups.
Compared to healthy controls, we found the OI samples to have significantly lower BV/TV and trabecular number (Tb.N.), significantly higher CV, trabecular separation (Tb.Sp.) and trabecular separation standard deviation (Tb.Sp.SD), but no differences in trabecular thickness (Tb.Th.). These results are in agreement with previous studies. The stiffnesses of highly heterogeneous ROIs were randomly lower with respect to the fabric-elasticity relationships, which reflects the limit of validity of the computational homogenisation methodology. This limitation does not challenge the fabric-elasticity relationship, which extrapolation to heterogeneous ROIs is probably reasonable but can simply not be evaluated with the employed homogenisation methodology. Moreover, due to their low BV/TV, the potential (unknown) errors on these heterogeneous ROIs would have negligible influence on whole bone stiffness in comparison to homogeneous ROIs which are orders of magnitude stiffer.
The filtering of highly heterogeneous ROIs removed these low stiffness ROIs and led to similar correlation coefficients for both OI and healthy groups. Finally, the BV/TV and DA matched data revealed no significant differences in fabric-elasticity parameters between OI and healthy individuals. Moreover, the filtering step did not exclude a particular OI type. Compared to previous studies, the stiffness constants from the 61 μm resolution HR-pQCT ROIs were lower than for the 36 μm resolution μCT ROIs.
In conclusion, OI trabecular bone of the distal tibia was shown to be significantly more heterogeneous and have a lower BV/TV than healthy controls. Despite the reduced linear regression parameters found for HR-pQCT images, the fabric-elasticity relationships between OI and healthy individuals are similar when the trabecular bone ROIs are sufficiently homogeneous to perform the computational stiffness analysis. Accordingly, the elastic properties used for FEA of healthy bones are also valid for OI bones.
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•Osteogenesis Imperfecta (OI) bone tissue is more mineralized compared to healthy.•OI trabecular bone presents lower bone volume fraction and higher heterogeneity.•OI trabecular architecture is not degraded for BV/TV and fabric similar to healthy.•HR-pQCT-based homogenized FE can be used for OI trabecular bone stiffness analysis.•Coarser scan resolution (HR-pQCT vs μCT) leads to lower stiffness constants.
•We develop a simple yet effective framework to compare the results of several search engines.•We present statistical tests based on outlier detection pointing out potential biases.•We propose two ...meta engines aiming at reducing bias.•We describe a publicly-available tool implementing the comparison, performing the tests, and showing the two meta-engine rankings.•We carry out extensive comparisons and bias investigations through a campaign of searches.
The search neutrality debate stems from content or service providers complaining about being discriminated and ranked unfairly low by search engines, raising the need for methodologies and tools to verify bias in search engine rankings.
For that purpose, we propose in this paper a simple yet effective framework based on the comparison of the results provided by several search engines, and build the corresponding tool to carry out a campaign of tests.
The main objectives are to develop an interpretable model of search engine behaviors and to design statistical tests pointing out suspicious instances as possible bias, without knowing the detailed ranking algorithms implemented by search engines. Our approach consists in reasoning in terms of the visibility that search engines give webpages when ranking them among their results; different types of possible bias can then be detected using statistical tests for outlier detection.
We apply this methodology to a test campaign over the most searched terms, which highlights some similarities and discrepancies among search engines, and possible instances of bias. Our approach can be of interest to regulators or any actor in the Internet, and is directly applicable to any search term through a publicly-available tool performing extensive comparisons and bias investigations, and offering two (bias-reducing) meta rankings.
A new peptidomimetic is proposed, resulting from substitution of the CO carbonyl group by a B–F bond at the amide linkage. The effects of such chemical alteration are theoretically investigated ...through comparative calculations on dimethyl-fluoro-aminoborane H3C–BF–NH–CH3 and N-methylacetamide H3C–CO–NH–CH3, the simplest model of a peptide linkage. While little difference is found regarding size, electronic structure, and plaque rigidity, substantial distinctions are, however, observed between the polarities and association energies of the two compounds, with a B–F···H–N hydrogen bond estimated to be about one-third as strong as the natural CO···H–N one. The conformational maps of the corresponding dipeptide models exhibit similarities and distinctions, which partly account for helical oligomer properties. Although capable of a high level of organization, the chains made of fluoro-aminoborane units show overall less structuration and more plasticity than their peptidic counterparts. Contrasts with fluorine-containing peptidomimetic 2-fluoro-2-butene are further underlined.
We present a study of multiple sclerosis segmentation algorithms conducted at the international MICCAI 2016 challenge. This challenge was operated using a new open-science computing infrastructure. ...This allowed for the automatic and independent evaluation of a large range of algorithms in a fair and completely automatic manner. This computing infrastructure was used to evaluate thirteen methods of MS lesions segmentation, exploring a broad range of state-of-theart algorithms, against a high-quality database of 53 MS cases coming from four centers following a common definition of the acquisition protocol. Each case was annotated manually by an unprecedented number of seven different experts. Results of the challenge highlighted that automatic algorithms, including the recent machine learning methods (random forests, deep learning, …), are still trailing human expertise on both detection and delineation criteria. In addition, we demonstrate that computing a statistically robust consensus of the algorithms performs closer to human expertise on one score (segmentation) although still trailing on detection scores.
High-flow nasal cannula (HFNC) is increasingly used in the management of acute and chronic respiratory failure. Little is known about the optimal settings for HFNC. This study was designed to assess ...the dose effect of HFNC on respiratory effort indexes and respiratory patterns in spontaneously breathing adults.
A randomized controlled crossover study was conducted in 10 healthy subjects. Five experimental conditions were evaluated: baseline with no therapy; 5 L/min with conventional nasal prongs; and HFNC at 20, 40, and 60 L/min. The primary outcomes were the indexes of respiratory effort (ie, esophageal pressure swing ΔP
, esophageal pressure-time product, and work of breathing). Secondary outcomes included breathing pattern parameters and blood gases. Dead-space ventilation and washout were calculated based on minute ventilation, breathing frequency, and Radford equations.
ΔP
increased from median (interquartile range IQR 3.2 (2.2-3.6) cm H
O at baseline to median (IQR) 5.7 (4.6-6.8) cm H
O at 60 L/min (
< .001). Neither esophageal pressure-time product nor work of breathing were modified during the tested conditions. The minute volume was significantly reduced at 40 and 60 L/min compared with baseline
= .04), mostly driven by an important and dose-dependent reduction in breathing frequency, from median (IQR) 16 (15-18) breaths/min at baseline, to median (IQR) 8 (7-10) breaths/min at 60 L/min (
< .001). Capillary Formula: see text was stable in all the tested conditions. The calculated dead-space ventilation was reduced by half with HFNC.
HFNC did not significantly modify work of breathing in healthy subjects. However, a significant reduction in the minute volume was achieved, capillary Formula: see text remaining constant, which suggests a reduction in dead-space ventilation with flows > 20 L/min. (ClinicalTrials.gov registration NCT02495675).
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