On the propagation of disturbances in certain fluid flows

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Tendances parmi les candidats en ophtalmologie non jumelés dans le cadre du Service canadien de jumelage des résidents

Background: Applicants to ophthalmology have high rates of going unmatched during the CaRMS process, but how this compares to other competitive or surgical specialties remains unclear. Our research aims to examine this phenomenon by identifying trends and comparing match data with other specialties, to identify disparities that may inform the need for future interventions to improve the match process for applicants. Methods: We used a cross-sectional analysis of data provided by CaRMS on the residency match from 2013 to 2022. Results: We obtained data from 608 ophthalmology, 5,153 surgery, and 3,092 top five (most competitive) specialty first choice applicants from 2013-2022. Ophthalmology applicants were more likely to go unmatched (18.9% [120/608]) than applicants to the top five (11.9% [371/3,092]) and surgical (13.5% [702/5,153]) specialties (p<0.001) and were twice as likely to rank no alternate disciplines (31.8%, p < 0.001) over the study period. In the first iteration, when alternate disciplines were ranked, the match rate to alternate disciplines was highest for ophthalmology applicants (0.41, p < 0.001). The majority (57.8%) of unmatched ophthalmology applicants do not participate in the second iteration. Conclusion: Compared to other competitive specialties, first choice ophthalmology applicants were more likely to go unmatched, rank no alternate disciplines, and choose not to participate in the second iteration. Ophthalmology applicant behaviours should be further studied to help explain these study findings.Contexte : Les candidats à l'ophtalmologie ont un taux élevé de non-jumelage au cours du processus CaRMS, mais une comparaison avec d'autres spécialités compétitives ou chirurgicales reste à faire. Notre travail a pour but d’examiner ce phénomène en identifiant des tendances et en comparant les données de jumelage avec celles d'autres spécialités, à la recherche de disparités susceptibles d'éclairer le besoin d'interventions futures pour améliorer le processus de jumelage pour les candidats. Méthodes : Nous avons procédé à une analyse transversale des données fournies par CaRMS sur le jumelage des résidents de 2013 à 2022. Résultats : Nous avons obtenu des données sur 608 candidats en ophtalmologie, 5 153 en chirurgie et 3 092 candidats dont le premier choix était l’une des cinq spécialités les plus compétitives de 2013 à 2022. Les candidats en ophtalmologie étaient plus susceptibles de ne pas être jumelés (18,9 % [120/608]) que les candidats aux cinq spécialités les plus compétitives (11,9 % [371/3 092]) et aux spécialités chirurgicales (13,5 % [702/5 153]) (p<0,001), et étaient deux fois plus susceptibles de ne classer aucune autre discipline (31,8 %, p<0,001) au cours de la période d'étude. Lors du premier tour, lorsque des disciplines alternatives ont été classées, le taux de jumelage avec les disciplines alternatives était le plus élevé pour les candidats en ophtalmologie (0,41, p<0,001). La majorité (57,8 %) des candidats non jumelés en ophtalmologie ne participent pas au deuxième tour. Conclusion : Comparativement à d'autres spécialités compétitives, les candidats dont le premier choix étaient l’ophtalmologie étaient plus susceptibles de ne pas être jumelés, de ne pas classer d'autres disciplines et de choisir de ne pas participer au deuxième tour. Les comportements des candidats en ophtalmologie devraient faire l'objet d'études plus approfondies afin d'expliquer nos résultats

Double Kelvin waves in a two-layer sea

It is shown that a depth change such as a fault line acts as a wave guide to long period waves in a two-layer rotating sea, in a similar way to the Double Kelvin waves of Longuet-Higgins (1968a, b) for a homogeneous sea. For a sea with a step discontinuity in depth, the effect of an extra layer leads to only small changes in the dispersion characteristics. For a continuous monotonic depth change taking place over a width l it is found that as l increases the Double Kelvin wave period increases, and the elevation at the interface decreases relative to the free surface elevation. Finally the effect of a time periodic wind stress suddenly applied is considered for step discontinuity in depth. For a maximum wind stress of 1 dyne the free surface wave amplitudes of the Double Kelvin wave are significantly less than those given by Mysak (1968). The corresponding interface amplitudes are about 10 cm. It is suggested, unlike their one-layer counterparts, that it may be possible to detect the two-layer waves successfully in practice, since they are predicted to have relatively large elevations at the interface

Interventions for treating hyperemesis gravidarum.

BACKGROUND: Hyperemesis gravidarum is a severe form of nausea and vomiting in pregnancy affecting 0.3% to 1.0% of pregnancies, and is one of the most common indications for hospitalization during pregnancy. While a previous Cochrane review examined interventions for nausea and vomiting in pregnancy, there has not yet been a review examining the interventions for the more severe condition of hyperemesis gravidarum. OBJECTIVES: To assess the effectiveness and safety, of all interventions for hyperemesis gravidarum in pregnancy up to 20 weeks\u27 gestation. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group\u27s Trials Register and the Cochrane Complementary Medicine Field\u27s Trials Register (20 December 2015) and reference lists of retrieved studies. SELECTION CRITERIA: Randomized controlled trials of any intervention for hyperemesis gravidarum. Quasi-randomized trials and trials using a cross-over design were not eligible for inclusion.We excluded trials on nausea and vomiting of pregnancy that were not specifically studying the more severe condition of hyperemesis gravidarum. DATA COLLECTION AND ANALYSIS: Two review authors independently reviewed the eligibility of trials, extracted data and evaluated the risk of bias. Data were checked for accuracy. MAIN RESULTS: Twenty-five trials (involving 2052 women) met the inclusion criteria but the majority of 18 different comparisons described in the review include data from single studies with small numbers of participants. The comparisons covered a range of interventions including acupressure/acupuncture, outpatient care, intravenous fluids, and various pharmaceutical interventions. The methodological quality of included studies was mixed. For selected important comparisons and outcomes, we graded the quality of the evidence and created \u27Summary of findings\u27 tables. For most outcomes the evidence was graded as low or very low quality mainly due to the imprecision of effect estimates. Comparisons included in the \u27Summary of findings\u27 tables are described below, the remaining comparisons are described in detail in the main text.No primary outcome data were available when acupuncture was compared with placebo, There was no clear evidence of differences between groups for anxiodepressive symptoms (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.73 to 1.40; one study, 36 women, very low-quality evidence), spontaneous abortion (RR 0.48, 95% CI 0.05 to 5.03; one study, 57 women, low-quality evidence), preterm birth (RR 0.12, 95% CI 0.01 to 2.26; one study, 36 women, low-quality evidence), or perinatal death (RR 0.57, 95% CI 0.04 to 8.30; one study, 36 women, low-quality evidence).There was insufficient evidence to identify clear differences between acupuncture and metoclopramide in a study with 81 participants regarding reduction/cessation in nausea or vomiting (RR 1.40, 95% CI 0.79 to 2.49 and RR 1.51, 95% CI 0.92 to 2.48, respectively; very low-quality evidence).In a study with 92 participants, women taking vitamin B6 had a slightly longer hospital stay compared with placebo (mean difference (MD) 0.80 days, 95% CI 0.08 to 1.52, moderate-quality evidence). There was insufficient evidence to demonstrate a difference in other outcomes including mean number of episodes of emesis (MD 0.50, 95% CI -0.40 to 1.40, low-quality evidence) or side effects.A comparison between metoclopramide and ondansetron identified no clear difference in the severity of nausea or vomiting (MD 1.70, 95% CI -0.15 to 3.55, and MD -0.10, 95% CI -1.63 to 1.43; one study, 83 women, respectively, very low-quality evidence). However, more women taking metoclopramide complained of drowsiness and dry mouth (RR 2.40, 95% CI 1.23 to 4.69, and RR 2.38, 95% CI 1.10 to 5.11, respectively; moderate-quality evidence). There were no clear differences between groups for other side effects.In a single study with 146 participants comparing metoclopramide with promethazine, more women taking promethazine reported drowsiness, dizziness, and dystonia (RR 0.70, 95% CI 0.56 to 0.87, RR 0.48, 95% CI 0.34 to 0.69, and RR 0.31, 95% CI 0.11 to 0.90, respectively, moderate-quality evidence). There were no clear differences between groups for other important outcomes including quality of life and other side effects.In a single trial with 30 women, those receiving ondansetron had no difference in duration of hospital admission compared to those receiving promethazine (MD 0.00, 95% CI -1.39 to 1.39, very low-quality evidence), although there was increased sedation with promethazine (RR 0.06, 95% CI 0.00 to 0.94, low-quality evidence) .Regarding corticosteroids, in a study with 110 participants there was no difference in days of hospital admission compared to placebo (MD -0.30, 95% CI -0.70 to 0.10; very low-quality evidence), but there was a decreased readmission rate (RR 0.69, 95% CI 0.50 to 0.94; four studies, 269 women). For other important outcomes including pregnancy complications, spontaneous abortion, stillbirth and congenital abnormalities, there was insufficient evidence to identify differences between groups (very low-quality evidence for all outcomes). In other single studies there were no clear differences between groups for preterm birth or side effects (very low-quality evidence).For hydrocortisone compared with metoclopramide, no data were available for primary outcomes and there was no difference in the readmission rate (RR 0.08, 95% CI 0.00 to 1.28;one study, 40 women).In a study with 80 women, compared to promethazine, those receiving prednisolone had increased nausea at 48 hours (RR 2.00, 95% CI 1.08 to 3.72; low-quality evidence), but not at 17 days (RR 0.81, 95% CI 0.58 to 1.15, very low-quality evidence). There was no clear difference in the number of episodes of emesis or subjective improvement in nausea/vomiting. There was insufficient evidence to identify differences between groups for stillbirth and neonatal death and preterm birth. AUTHORS\u27 CONCLUSIONS: On the basis of this review, there is little high-quality and consistent evidence supporting any one intervention, which should be taken into account when making management decisions. There was also very limited reporting on the economic impact of hyperemesis gravidarum and the impact that interventions may have.The limitations in interpreting the results of the included studies highlights the importance of consistency in the definition of hyperemesis gravidarum, the use of validated outcome measures, and the need for larger placebo-controlled trials

Reporting of equity in observational epidemiology: a methodological review

Background Observational studies can inform how we understand and address persisting health inequities through the collection, reporting and analysis of health equity factors. However, the extent to which the analysis and reporting of equity-relevant aspects in observational research are generally unknown. Thus, we aimed to systematically evaluate how equity-relevant observational studies reported equity considerations in the study design and analyses. Methods We searched MEDLINE for health equity-relevant observational studies from January 2020 to March 2022, resulting in 16 828 articles. We randomly selected 320 studies, ensuring a balance in focus on populations experiencing inequities, country income settings, and coronavirus disease 2019 (COVID-19) topic. We extracted information on study design and analysis methods. Results The bulk of the studies were conducted in North America (n = 95, 30%), followed by Europe and Central Asia (n = 55, 17%). Half of the studies (n = 171, 53%) addressed general health and well-being, while 49 (15%) focused on mental health conditions. Two-thirds of the studies (n = 220, 69%) were cross-sectional. Eight (3%) engaged with populations experiencing inequities, while 22 (29%) adapted recruitment methods to reach these populations. Further, 67 studies (21%) examined interaction effects primarily related to race or ethnicity (48%). Two-thirds of the studies (72%) adjusted for characteristics associated with inequities, and 18 studies (6%) used flow diagrams to depict how populations experiencing inequities progressed throughout the studies. Conclusions Despite over 80% of the equity-focused observational studies providing a rationale for a focus on health equity, reporting of study design features relevant to health equity ranged from 0–95%, with over half of the items reported by less than one-quarter of studies. This methodological study is a baseline assessment to inform the development of an equity-focussed reporting guideline for observational studies as an extension of the well-known Strengthening Reporting of Observational Studies in Epidemiology (STROBE) guideline

Constitutive relations for anisotropic soils

SIGLEAvailable from British Library Document Supply Centre- DSC:DX89154 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Roof truss systems under blast loads

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Designing roof systems for blast loading is quite complex. Many uncertainties still exist in this vital research area. The typical single degree of freedom dynamic modeling approach that is used widely by the blast design community is based on idealization of the structural components. Limited information exists on the blast response of different roof systems and their blast design methodology is lacking. Moreover, the blast roof load is based on approximate methods to produce a blast wave equivalent to the actual propagated wave. This approximation needs to be evaluated to ensure the blast designs are sufficient. The uncertainty of blast loads and roof resistance can lead to either excessive costs or insufficient blast designs. Therefore, the research presented here aims to bridge the gap in the knowledge about the blast resistance of different roof systems; Open Web Steel Joist (OWSJ) systems and Cold-Formed Steel (CFS) roof systems as well as to assess the accuracy of the existing ASCE and UFC approximate roof blast loads. In this dissertation, dynamic analyses using the finite element method were performed on a roof component to compare the dynamic responses resulting from a propagated blast wave and the current equivalent blast load techniques. Blast field data were used to verify the dynamic finite element model. Results have shown that current methodologies should be corrected if used to design for blast loading. Previous experiments were used to verify advanced finite element models developed to predict the complete static resistance of OWSJs including the failure limits. The verified models were used to perform dynamic analyses to predict the system dynamic response under equivalent blast loads. Analyses and energy comparisons at superficial damage level showed that the current methodology, used to calculate OWSJ static resistance, predicted 27% and 88% higher energies than the experimental ones for 16K5 and 26K5 joists, respectively. While at moderate damage levels current methodology predicted 47% and 108% higher energies than the experimental ones for 16K5 and 26K5 joists. Evaluating the blast resistance of CFS roof systems is challenging. There is a lack of existing design guidelines and response criteria for CFS roof systems. The UFC manual provides information that is relevant to CFS panels only. The approach that was adopted in this dissertation started with an extensive testing program of different types of end connections used for CFS roof trusses to investigate their failure capacities in horizontal and vertical directions. Analyses of the experimental results showed that using Hilti PAFs are more favorable than using bolts for supporting CFS truss end-connections as it was indicated in their strength and toughness. Moreover, the experimental results were used to verify the deformable screw behavior and the finite element model developed to predict the progressive failure of the truss end-connections. Small-scale CFS roof truss specimens were tested to failure under quasi-static loading. The static resistance of these systems and the associated failure mechanisms were identified. Experimental results and energy comparisons show that the truss layout and the shape of loading significantly affect the performance of the truss and the failure mechanism. Three-dimensional numerical models were developed and verified against the experimental results. The advanced models predicted the static resistance to failure with a high level of accuracy. Numerical analyses were performed to enhance the static resistance of CFS roof systems for blast analysis. Experimental and numerical analyses have shown that the energy absorbed is improved significantly when the web members susceptible to buckling are strengthened. In addition, the numerical models were used to perform dynamic analyses on a flat CFS roof system subjected to different threat levels. Von Mises stress distributions were used to investigate and determine the damage level corresponding to each threat level. The research presented in this dissertation focused on investigating the equivalent roof blast load as well as the blast resistance of different roof truss systems. The static resistance required for SDOF analysis was evaluated and identified using physical experiments and verified advanced finite element models. Failure capacities of truss end-connections were identified to improve truss system performance against blast. Based on experimental and numerical analyses, recommendations are given to arrive at an enhanced blast resistance. Dynamic analyses on 3D truss numerical models were used to investigate the damage level under certain threats. It is recommended for future work to perform field tests to address the critical differences between the measured field roof wave and the UFC manual roof blast wave. The developed numerical models can be potentially used as an analysis tool to investigate the resistance of other truss profiles and to examine the failure mechanisms that may lead to the development of an analytical model for the static resistance of roof systems. It is recommended for future work to compare the dynamic analyses performed using the developed numerical models and the SDOF dynamic analysis to provide more insight into the idealization of this technique

Numerical modeling of static nonlinear behavior of cold-formed steel stud walls

Title from PDF of title page; abstract from research PDF (University of Missouri--Columbia, viewed on June 26, 2014).[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Cold-formed steel studs have been approved for their blast-resistance capability. Research concerns nowadays focus on how to adapt and develop the wall system to resist different levels of blast threats. Recently, experimental investigations were conducted to evaluate several proposed ways to enhance stud resistance against moderate blast loading. However, lab testing is of a time and a cost consuming nature. Consequently, the provision to develop a comprehensive numerical model for cold-formed steel stud walls using various connection details and bracing scenarios is urgently needed. This research puts a spotlight upon the nonlinear finite element analysis focusing on developing a suitable numerical model using ABAQUS as a finite element analysis tool. The developed model passed through a series of verifications using existing quasi-static tests data, obtained over the past 10 years, to examine the model efficiency in tracing the full load-deflection response of the wall system. The verified model was exploited to study the effect of stud gauge and screw configuration on the blast resistance. To provide an alternative tool to performing lab experiments, a failure criterion was developed, based on the different limit states of the wall components, to predict the model failure point from which the toughness was estimated. Applying ABAQUS along with the developed failure criterion, the overall performance of steel stud walls was investigated and analyzed through a total of twenty numerical simulations