bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Validation of a Dynamic Numerical Model for Timing Belt Drives Behavior Simulation
Authors: Manin Lionel , Play Daniel , Soleilhac Patrick
Published: December 2020

The behavior of timing belts used in automotive applications have to be defined and predicted at the preliminary design phases. Numerical simulations replace progressively experimental determinations that are time and money consuming.

The object of the work was to qualify from experimental results a timing belt drive numerical model. The model simulates the dynamic behavior versus time of any kind of tooth belt power transmissions. The model architecture, originalities and capabilities have been already presented, and the purpose is now to compare in details numerical and experimental results.

The experimental qualification has been carried out on a laboratory test bench with a medium size engine valve controlled distribution made of 3 pulleys and a tensioner. Tensions, camshaft torque, pulleys speeds and angular acylisms, dynamic transmission error between camshaft and crankshaft pulleys have been measured. Numerous tests have been made for different running conditions by changing : speed, angular acyclism, camshaft torque, setting tension. Several phenomena and influence of parameters have been identified, as the pulley eccentricity effect on camshaft torque, span tensions, and transmission error. Part of the experimental results are used as entries of the model : camshaft torque, crankshaft instantaneous speed, transmission error due to pulley eccentricities. Further, comparisons with the numerical results were made. Experimental and numerical results of tension, angular acyclism, dynamic transmission error, versus operation time are compared for the different tests performed. The agreement is good and shows that the model developed allows to simulate dynamic behavior of timing belt with high degree of confidence.
Probability of Load-Carrying Ability of Two-Profile Chain Drives
Authors: Kryvyy Petro D. , Bey Ihor M. , Shymanska Oksana I. , Kryvyy Petro P.
Published: December 2020

The analysis of the available calculation methods of chain-drives load-carrying ability is given according to the criterion of the tolerance unit pressure in a single profile chain joint [p]0. It is shown, that the values of [p]0 were determined according to the deterministic ideas without consideration of the distribution law of both random varieties of contact step of inner and outer rings and lengths of drive strands of the first and second profile of the chain drive.

Probability task of determination of the tolerance unit pressure in two profile chain joints [p0]q is solved, when the structural, technological and physical-mechanical characteristic of the chain, that is, the lengths of drive strand of a chain-drive, accuracy of contact steps and stiffness of a drive roller chain are considered.

The measurement procedure and the empirical dependencies for determination of drive roller chains deformation and stiffness are presented.

As a result, the dependencies for the determination of [p0]q as the basic criterion according to which selection of a chain dimension-type, as well as characteristics used for the comparative estimation of a drive chain quality of different manufacturers when certain probability estimations are taken into consideration, were obtained.
Finishing of Tooth Flanks of Pinion Cutter With Profiled Grinding Wheel in Consideration of Accuracy of Cutting Edge After Regrinding
Authors: Yoshino Hidehiro , Ohshima Fumihiro , Shao Ming
Published: December 2020

Two kinds of relief grinding methods for pinion cutters with profiled grinding wheels are proposed. One method finishes an involute pinion cutter with almost no regrinding error by giving the helical motion smaller or larger than that corresponding to the helix angle of the pinion cutter. Another is for a pinion cutter with an arbitrary profile, including the involute pinion cutter with a modified profile or protuberance. The tooth flank is finished by giving the three motions, i.e., the helical and approaching motions between the grinding wheel and work pinion cutter and the shifting motion of the grinding wheel. The profile calculation was conducted by using the element removal method. It was shown that the regrinding errors of the pinion cutters being finished by the proposed methods become smaller than that of pinion cutters finished by giving only the approaching motion (conventional method). The finishing tests of the involute helical pinion cutters were carried out on the CNC gear form-grinding machine with the four controlled axes. The profiles of cutting edges of the finished pinion cutters almost agreed with the calculated ones.
Influence of Design Parameters and Tooth Profile Modification for Reducing Gear Transmission Error
Authors: Guingand Michèle , de Vaujany Jean-Pierre , Cheval Cédric , Play Daniel
Published: December 2020

The subject of this paper is to propose a method for designing spur external cylindrical gears. The goal is to optimize global and local design parameters in order to minimize meshing noise. Amplitude of the loaded transmission error has been chosen as a criteria. An optimization process is then proposed. It uses equations from systematic statistical analysis.
Friction Forces As a Dynamic Excitation Source in Involute Spur and Helical Gearing
Authors: Hochmann David , Houser Donald R.
Published: December 2020

Current thought is that the main sources of dynamic excitation in spur and helical gearing occur along the line-of-action and are due to time varying tooth stiffness and static transmission error. This paper examines friction forces as a potential dynamic excitation source in the gear mesh of involute parallel axis spur and helical gearing. The friction forces act in a direction perpendicular to the line-of-action, defined as the off line-of-action direction.

To support the claim that friction force is a potential dynamic excitation source, experimental evidence is presented in the form of shaft motions measured near the support bearings in the line-of-action and off line-of-action directions. These experimental results show that the off line-of-action motion is of the same order of magnitude as the line-of-action motion and at times the off line-of-action motion at gear mesh frequency is several times larger than the line-of-action motion. The motions are related to the forces through the bearing stiffness matrix. Other potential explanations of the large off line-of-action shaft motion such as bearing cross coupling phenomena, reduced bearing stiffness, bearing clearances, and system dynamics are examined.

The results suggest that through a combination of a small friction force excitation at the gear mesh, and the force transmissibility properties of the gear-bearing system, the friction force can produce forces at the bearing comparable to those generated by transmission error excitations, particularly at low to medium speeds.
Dynamics of Hypoid Gear Transmission With Non-Linear Time-Varying Mesh
Authors: Cheng Yuping , Lim Teik C.
Published: December 2020

A new generalized 14 degrees-of-freedom dynamic model with coupled translation-rotation effect is developed for simulating the nonlinear vibratory response of hypoid geared rotor systems. The model incorporates the load-dependant time-varying mesh characteristic vectors due to tooth load sharing and profile modifications, backlash non-linearity, and off line-of-action friction forces. Based on the 3-dimensional tooth contact analysis results, the quasi-static mesh characteristics that describe the translation-rotation and rotation-rotation force couplings are obtained for use in the dynamic formulation. The three-dimensional representations of the mesh vectors, normal and friction forces, and moments generated at the mesh interface are also included in the proposed study. Tooth separation and the occurrence of jump phenomenon observed in the predicted frequency response functions are analyzed.
Experimental Study and Numerical Simulation of Vibration and Noise of Planetary Gears
Authors: Shoda Katsuhiko , Furukawa Toyoaki , Iwanaga Youichi , Matsunami Yuji
Published: December 2020

This paper presents experimental study and numerical simulation of vibration and noise of a speed increaser, which consist of a star type planetary gears and a planetary type epicyclic gear train. The ring mode vibration of internal gear in the star type planetary gears and torsional vibration of planetary gear in the planetary type epicyclic gear train are measured by use of telemetry system. The influence of tooth profile error for the vibration and the noise is clarified. The numerical simulation is also carried out to evaluate the exciting force and it’s associated vibration. In this method, the coupled vibration of shaft bending, torsional and ring mode vibration of the internal gear are taken into account employing modal synthesis method. The simulation results shows a good agreement with the experimental ones. And it is found that the ring mode vibration magnifies the higher order component of gear mating frequency.
Lubrication System Failure Baseline Testing on an Aerospace Quality Gear Mesh
Authors: Handschuh Robert F. , Morales Wilfredo
Published: December 2020

Aerospace drive systems are required to survive a loss-of-lubrication test for qualification. In many cases emergency lubrication systems need to be designed and utilized to permit the drive system to pass this difficult requirement. The weight of emergency systems can adversely affect the mission capabilities of the aircraft. The possibility to reduce the emergency system weight through the use of mist lubrication will be described. Mist lubrication involves the delivery of a minute amount of a lubricant as a vapor or fine mist in flowing compressed air to rubbing surfaces. At the rubbing surface, the vapor or mist reacts to form a solid lubricating film. The aim of this study was to establish a baseline for gear behavior under oil depleted conditions. A reactive vapor-mist lubrication method is described and proposed as a candidate emergency lubrication system.
Fundamental Characteristics of a New Variable Torque Clutch With Skewed Rollers
Authors: Feng Ming , Ono Kyosuke , Mimura Kenji
Published: December 2020

In this paper, a new variable torque clutch with skewed rollers, in which the cylinder rollers and the inner and outer races are assembled like a conical roller bearing except that each roller axis inclines with an equal angle to the races axis, was introduced and then investigated theoretically and experimentally. The geometry of the race surface was analyzed and the parametric equations of contact line etc. were derived. A roller-wedge model, based on the motion relationship between the skewed rollers and the two races, was proposed for this clutch. From the static equilibrium condition of the roller, the transmitted torque capacity and kinematics characteristics are evaluated properly. Several prototypes of this clutch were manufactured and measured to show the validity of this design idea and the theoretical results. The computation results were found to in good agreement with the experimental data. In addition, the influences of design parameters on the fundamental characteristics of the variable torque clutch are discussed in detail.
The Evolution of Gear Spindles
Authors: Mancuso Jon R. , Zilberman Joe
Published: December 2020

Gear spindles were first applied to rolling mills in the early 1950’s. Over this time the basic design has remained constant except for the material used and the hardening process. And today they are still the most commonly used drive for rolling mills. This is because they are power dense (handle the highest torque for a given Outside Diameter), easy to maintain and economical. New processes have been developed for grinding carburized gear spindles to optimize tooth contact thereby increasing spindle capacity and life by 30–100%. This process allows for a more compact design (usually one size smaller) along with improved life.
Fatigue Life Extension by Surface Enhancement
Authors: Manesh Ali , Doubts Thomas L. , Mallett Edward J.
Published: December 2020

To increase predictable life of precision gears, requires a process which simultaneously produces the required geometry accuracy and surface finish, as well as the desired state of compressive residual stress at the part surface. The goal is to increase power throughput by optimizing the surface properties of the gears, without compromising tooth scoring resistance. In this experiment, four different surface enhancement processes were selected, implemented, and tested. Rolling Sliding Contact Fatigue tests were used to qualify the percentage of improvement. A set of test specimens were also made without any of the surface enhancements above. These specimens were used as the baseline for comparison.

9310 steel was used as the material to prepare the test specimens. All specimens were carburized, hardened and ground to the aerospace specification. Gear Research Institute conducted testing on all samples. The baseline specimens were all run in high-load, short-cycle tests and they failed in the predicted manner with expected scatter. The performance of some surface-enhanced specimens exceeded the performance of the baseline specimens. Improved life-to-failure rates were as high as 10%.

This paper will discuss the test specimen preparation processes, testing process and results of this project. It also includes recommendations for future work in surface enhancement.
An Investigation Into the Design of Hollow Accumulator Rolls Using Finite Element Analysis
Authors: Viviano Anthony V. , Suchora Daniel H. , Pierson Hazel M.
Published: December 2020

Accumulator systems consist of a series of accumulator rolls, arranged either vertically or horizontally, used in many sheet processing lines for the purpose of storing up strip. Literature on roll design for this particular type of roll is scarce. Much of the present design theory is based on a static analysis assuming the entire contact load from the strip is uniformly distributed over the roll. A previous paper done on this subject focused on modeling the roll using finite element analysis (FEA) assuming this uniform pressure load on the roll.

The purpose of this work was to incorporate non-linear contact elements between the strip and the roll body in a finite element analysis. This would allow the software to distribute the load from the strip to the roll, taking into account friction and contact losses. Once accomplished, this load was placed on various roll design configurations, of which included variation in the number of roll stiffeners and the thickness of the roll body and the end plates. These results were also compared to the previous uniform pressure FEA in order to assess the validity of the uniform pressure assumption. Based on these results, a roll design methodology is presented.
Development of Impact Resistant Optical Pick-Up for Portable Disk Products
Authors: Iwata Yukihiro , Inoue Hiroto , Tsuji Kenji , Hosokawa Kazuhiko
Published: December 2020

Concerning the development of portable optical disk products, higher impact resistant of the optical pick-up is required. Conventionally, cut and try measures, mainly based on experiment were applied to these problems, and it took much time and cost.

Therefore, we developed this drop impact analysis of the optical pick-up based on the Finite Element Method (FEM) and clarified the failure mechanism of the suspension wire breaking with drop impact. With this analysis method, we also developed a new optical pick-up with a curved suspension wire, and realized much higher impact resistance.
A Model for Probabilistic Growth of Complex Fatigue Crack Shapes
Authors: Riddell William T.
Published: December 2020

A model for probabilistic growth of complex fatigue crack shapes that will be used to perform sensitivity studies and to optimize inspection intervals for railroad tank cars is presented. In this model, crack growth is based on results from a deterministic crack growth analysis with additional terms to introduce stochastic behavior. The family of complex shapes that cracks grow through is parameterized by a single degree of freedom, which simplifies the probabilistic model. Comparisons between experimental and numerical results suggest that the probabilistic model is capable of representing realistic crack growth using reasonable crack growth parameters, which will enable the sensitivity and optimization studies for which the model is intended.
More Reliable Evaluation of Train’s Vibration on Human Body
Authors: Drakatos P. A. , Karakassis K. , Kallaras M.
Published: December 2020

At the present research, we analyze the vibration levels, which take place during the operation of trains. Through this analysis via fuzzy logic theory, it is achieved the approximation of a model which will guide to a more reliable evaluation of the mechanical systems in order to ensure a comfort and safe trip. The train vibrations are usually low frequency, but for high doses they can have a harmful impact.
A Study on Contact Stress Analysis in Boundary Element Method
Authors: Çelik Mehmet
Published: December 2020

A numerical approach for the solution of the contact mechanics problems has been presented using the Boundary Element Method. An automatic load distribution technique is implemented in a contacting element using isoparametric quadratic elements. This type of element is shown to be excellent in modeling regions of rapidly varying stresses in the contact areas. The superposition method is applied to interference contact problems mostly used in engineering design of the systems. The work is focused on the analysis of the loading in a roller bearing housing.
Modeling the Ratcheting Phenomenon in an Austenitic Steel at Room Temperature
Authors: Zaki A. S. , Ghonem H.
Published: December 2020

This paper describes the cyclic accumulative plastic strain in a polycrystalline material when subjected to loading conditions promoting ratcheting behavior. For this purpose, a unified viscoplastic constitutive model based on non-linear kinematic hardening formulation is implemented. Identification of the model parameters was carried out using an experimental program that included monotonic, cyclic and relaxation testing. Simulation of the material response using the proposed model is compared with experimental results for the same loading. This comparison is used to evaluate the model validity.
Brownian motion-based nanoparticle sizing—A powerful approach for in situ analysis of nanoparticle-protein interactions
Authors: Nienhaus Karin , Nienhaus Gerd Ulrich
Published: December 2020

A key hurdle toward effective application of nanoparticles (NPs) in biomedicine is still the incomplete understanding of the biomolecular adsorption layer, the so-called protein corona, which inevitably forms around NPs when they are immersed in a biofluid. NP sizing techniques via the analysis of Brownian motions offer a powerful way to measure the thickness of the protein corona in situ. Here, the fundamentals of three techniques, dynamic light scattering, fluorescence correlation spectroscopy, and nanoparticle tracking analysis are briefly summarized. Then, experimental procedures for the determination of binding curves are presented in a tutorial fashion. Nanoparticle sizing experiments are illustrated with a selection of recent results on the interactions of transferrin with hydrophilic and hydrophobic polystyrene nanoparticles, and key insights gained from this work are discussed.
Area-selective aerosol jet fog deposition: Advancing large-area and sustainable fabrication
Authors: Mullapudi Kamesh , Murari Nishit M. , Mansergh Ryan H. , Keszler Douglas A. , Conley John F.
Published: December 2020

In this work, we demonstrate controlled area-selective deposition of aluminum oxide phosphate (AlPO) at room temperature and near atmospheric pressure using a potentially zero-waste aerosol jet fog (ajFOG) deposition system. Octyl-trichlorosilane (OTS-8) self-assembled monolayers (SAMs) are coated on SiO2/Si substrates to form a blanket hydrophobic functionalization. Next, ultraviolet/ozone exposure through a shadow mask removes OTS-8 in the exposed regions, creating a pattern of hydrophobic and hydrophilic regions. AlPO is selectively deposited onto the hydrophilic regions from an aqueous aerosol precursor fog of aluminum phosphate inorganic clusters. Smooth films with sharp boundaries are deposited. The AlPO features and defects in the hydrophobic areas are investigated as a function of feature size, SAM type/application method/exposure time, ajFOG process parameters, and underlying substrate.
Acquisition and analysis of scanning tunneling spectroscopy data—WSe2 monolayer
Authors: Feenstra Randall M. , Frazier Grayson R. , Pan Yi , Fölsch Stefan , Lin Yu-Chuan , Jariwala Bhakti , Zhang Kehao , Robinson Joshua A.
Published: December 2020

Acquisition and analysis are described for scanning tunneling spectroscopy data acquired from a monolayer of WSe2 grown on epitaxial graphene on SiC. Curve fitting of the data is performed, in order to deduce band edge energies. In addition to describing the details of the theoretical curves used for the fitting, the acquisition and analysis methods are also discussed within the larger context of the historical development of scanning tunneling spectroscopy techniques.
Patterns of Sedentary Time in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Youth
Authors: Bejarano Carolina M. , Gallo Linda C. , Castañeda Sheila F. , Garcia Melawhy L. , Sotres-Alvarez Daniela , Perreira Krista M. , Isasi Carmen R. , Daviglus Martha , Van Horn Linda , Delamater Alan M. , Savin Kimberly L. , Cai Jianwen , Carlson Jordan A.
Published: December 2020

Background: Total sedentary time and prolonged sedentary patterns can negatively impact health. This study investigated rates of various sedentary pattern variables in Hispanic/Latino youth. Methods: Participants were 956 youths (50.9% female) in the Hispanic Community Health Study/Study of Latinos Youth, a population-based cohort study of Hispanic/Latino 8- to 16-year-olds from 4 geographic regions in the United States (2012–2014). Total sedentary time and 10 sedentary pattern variables were measured through 1 week of accelerometer wear. Differences were examined by sociodemographic characteristics, geographic location, weekdays versus weekends, and season. Results: On average, youth were sedentary during 67.3% of their accelerometer wear time, spent 24.2% engaged in 10- to 29-minute sedentary bouts, and 7.2% in ≥60-minute bouts. 8- to 12-year-olds had more favorable sedentary patterns (less time in extended bouts and more breaks) than 13- to 16-year-olds across all sedentary variables. Sedentary patterns also differed by Hispanic/Latino background, with few differences across sex, household income, season, and place of birth, and none between weekdays versus weekends. Conclusions: Variables representing prolonged sedentary time were high among Hispanic/Latino youth. Adolescents in this group appear to be at especially high risk for unhealthy sedentary patterns. Population-based efforts are needed to prevent youth from engaging in increasingly prolonged sedentary patterns.
Optimization of Fluconazole Dosing for the Prevention and Treatment of Invasive Candidiasis Based on the Pharmacokinetics of Fluconazole in Critically Ill Patients
Authors: Boonstra J. M. , Märtson A. G. , Sandaradura I. , Kosterink J. G. W. , van der Werf T. S. , Marriott D. J. E. , Zijlstra J. G. , Touw D. J. , Alffenaar J. W. C.
Published: December 2020

The efficacy of fluconazole is related to the area under the plasma concentration-time curve (AUC) over the MIC of the microorganism. Physiological changes in critically ill patients may affect the exposure of fluconazole, and therefore dosing adjustments might be needed.
Efficacy and Pharmacokinetics of Fosmanogepix (APX001) in the Treatment of
Candida
Endophthalmitis and Hematogenous Meningoencephalitis in Nonneutropenic Rabbits
Authors: Petraitiene Ruta , Petraitis Vidmantas , Maung Bo Bo Win , Mansbach Robert S. , Hodges Michael R. , Finkelman Malcolm A. , Shaw Karen Joy , Walsh Thomas J.
Published: December 2020

Candida
endophthalmitis is a serious sight-threatening complication of candidemia that may occur before or during antifungal therapy. Hematogenous
Candida
meningoencephalitis (HCME) is also a serious manifestation of disseminated candidiasis in premature infants, immunosuppressed children, and immunocompromised adults.
Sphingolipid-Containing Outer Membrane Vesicles Serve as a Delivery Vehicle To Limit Macrophage Immune Response to Porphyromonas gingivalis
Authors: Rocha Fernanda G. , Ottenberg Gregory , Eure Zavier G. , Davey Mary E. , Gibson Frank C.
Published: December 2020

Sphingolipids (SLs) are essential structural components of mammalian cell membranes. Our group recently determined that the oral anaerobe
Porphyromonas gingivalis
delivers its SLs to host cells and that the ability of
P. gingivalis
to synthesize SLs limits the elicited host inflammatory response during cellular infection.
Using a Student-Generated Mock Magazine Issue To Improve Students’ Awareness of Diverse Scientists
Authors: Robison Jennifer D. , Berbari Nicolas F. , Rao Anusha S.
Published: December 2020

This study explores whether integrating multicultural content within a genetics laboratory course affected students’ awareness of diversity and their perceptions of scientists’ identities. Genetics laboratory curricula typically focus on content and experimental procedures, with cursory references to the scientists who made these discoveries. The resulting poor racial and gender representation in the curricula propagate biases about the abilities and contributions of scientists from underrepresented groups, which may adversely affect the retention and success of students in these groups. Initially, students completed a pre-test in which they were asked to recall the names of geneticists and their scientific contributions. Later students created a mock magazine issue featuring a diverse set of experts in genetics, specifically members of traditionally underrepresented gender/sexuality and/or racial/ethnic groups. To facilitate this assignment, students were randomly assigned a geneticist from a pool of active research scientists, spanning a wide range of scientific and cultural backgrounds and identities. Each student wrote a 500-word biography of their assigned geneticist and read biographies composed by peers. Then, in groups, the students categorized biographies based on student-selected unifying themes into a table of contents. On the final exam, the pre-test was repeated as a post-test. In the pre-test, scientists listed by students were 94% male and 6% female, with no members of other underrepresented groups included. In the post-test, scientists listed by students shifted to 84% male and 16% female with 18% from underrepresented groups. These data suggest that this intervention increases awareness of the multicultural nature of scientists.
Analysis of Serial Multidrug-Resistant Tuberculosis Strains Causing Treatment Failure and Within-Host Evolution by Whole-Genome Sequencing
Authors: Chen Xinchang , He Guiqing , Lin Siran , Wang Shiyong , Sun Feng , Chen Jiazhen , Zhang Wenhong
Published: December 2020

Few studies have focused on the reasons for the low cure rate of multidrug-resistant tuberculosis in China and within-host evolution during treatment, which is of great significance for improving clinical treatment regimens. Acquired resistance events were common during the ineffective treatment, among which resistance to amikacin and high-level moxifloxacin were the most common.
Ice-thickness variation during marine oxygen isotope stage 4–2 glaciation determined from kame terraces in the Rangitata Valley, New Zealand
Authors: Thackray* Glenn D. , Rittenour Tammy M. , Shulmeister James
Published: December 2020

An extensive kame-terrace sequence in the middle Rangitata Valley reveals ice-volume fluctuations spanning the last (Otiran) glaciation. Stratigraphic and sedimentologic characteristics document lateral ice-marginal processes and provide context for luminescence dating. The sequence provides novel and complementary data on glacier ice thickness, which fluctuated substantially throughout the Otiran glaciation. Thick ice constructed one of the highest kame terraces (540 m above the valley floor) ca. 68 ka and thinned nearly 500 m to the valley floor by ca. 53 ka. Following an episode of ice thickening to an unknown elevation, ice again thinned to the valley floor by ca. 44 ka. Ice thickened to its greatest late marine oxygen isotope stage (MIS) 3 extent of 480 m by ca. 37 ka, and thinned to 230 m by ca. 31 ka. The final ice expansion, to 260 m, occurred by ca. 25.5 ka, and the ice fluctuated and thinned to 240 m at ca. 22–20 ka and to 170 m at ca. 21–17 ka. Published cosmogenic radionuclide (CRN) ages indicate surface stabilization near the valley floor (55 m) by ca. 18 ka. This ice-thickness chronology provides an independently derived ice-volume record that is consistent with local and regional glacial chronologies. The site, lying between the Mackenzie Basin and the northern Canterbury Plains drainages, displays a chronology with advances correlative in part with each of those regions. Maximum ice extent occurred 70–65 ka in the Rangitata Valley and the Mackenzie Basin, while the subsequent ice expansion ca. 37 ka is similar in timing to chronologies in both the Rakaia Valley to the north and the Mackenzie Basin to the south.
Microbiological evaluation of corneal and contact lens cultures in contact lens-associated bacterial keratitis
Authors: Mukhtar Sabrina , Atta Sarah , Durrani Asad , Perera Chandrashan , Kowalski Regis , Jhanji Vishal
Published: December 2020

Purpose

To determine the degree of microbiological agreement between corneal scrapings and contact lens cultures in cases of contact lens-associated keratitis.

Methods

Electronic medical records of all cases of contact lens-associated keratitis at a single institution from April 2006 to May 2019 were reviewed. Cases where both corneal scrapings and contact lens cultures were obtained were included in the study. Group 1 demonstrated agreement between corneal scrapings and contact lens cultures. Group 2 demonstrated growth on both cultures, but disagreement in isolated organism. Group 3 demonstrated negative corneal cultures but growth on contact lens cultures and the diagnostic yield of contact lens microbiological cultures and agreement between corneal and contact lens cultures.

Results

A total of 80 eyes of 72 patients were included in the study. 135 total incidences of microbiological results were included for data analysis. Group 1 contained nine incidences (6.7%), group 2 contained 60 incidences (44.4%) and group 3 contained 66 incidences (49%). In group 3, 50% of the cases were treated based on contact lens culture data. There was no statistically significant difference between all three groups in terms of baseline characteristics, presenting vision, vision at last follow-up, number of antibiotics used or complications from keratitis. Pseudomonas was the most common microorganism isolated, and in 89% of these cases, there was disagreement between corneal and contact lens cultures.

Conclusions

Although there was a disagreement in the microbiological yield between contact lens and corneal cultures, contact lens cultures were useful in management of patients while achieving similar outcomes.
OCTA versus dye angiography for the diagnosis and evaluation of neovascularisation in punctate inner choroidopathy
Authors: Gan Yuhong , Zhang Xiongze , Su Yongyue , Shen Mei , Peng Yuting , Wen Feng
Published: December 2020

Purpose

To compare the sensitivity and specificity of identifying and evaluating the choroidal neovascularisation (CNV) in punctate inner choroidopathy (PIC) by optical coherence tomography angiography (OCTA) versus dye angiography.

Methods

Consecutive patients diagnosed with PIC were enrolled in this study from June 2016 to December 2019. During the same visit, each patient underwent comprehensive ophthalmological and multimodal imaging examinations. The diagnostic accuracy of different modalities was evaluated.

Results

The study included 160 affected eyes from 123 patients. Ninety-five eyes (59.38%) were identified with secondary CNV by multimodal imaging. The sensitivity and specificity for CNV detection with OCTA alone were 89.47% and 98.46%, respectively. OCTA also provided the morphology of CNV to determine the activity of CNV with a sensitivity of 86.67% and a specificity of 94.29%.

Conclusions

In this study, we investigated the utility of OCTA in the diagnosis and evaluation of patients with CNV secondary to PIC. Compared with dye angiography, OCTA show convincing diagnosis accuracy. Although OCTA has several limitations and is not sufficient to replace dye angiography in clinical practice, it can provide clinicians with a non-invasive way to monitor patients with CNV secondary to PIC and guide treatment decisions.
FIFA Sudden Death Registry (FIFA-SDR): a prospective, observational study of sudden death in worldwide football from 2014 to 2018
Authors: Egger Florian , Scharhag Jürgen , Kästner Andreas , Dvořák Jiří , Bohm Philipp , Meyer Tim
Published: December 2020

Objective

To investigate the underlying causes and regional patterns of sudden death in football (soccer) players worldwide to inform and improve existing screening and prevention measures.

Methods

From 2014 to 2018 cases of sudden cardiac death (SCD), survived sudden cardiac arrest (SCA) and traumatic sudden death were recorded by media monitoring (Meltwater), a confidential web-based data platform and data synchronisation with existing national Sudden Death Registries (n=16). Inclusion criteria were met when sudden death occurred during football-specific activity or up to 1 hour afterwards. Death during other activities was excluded.

Results

A total of 617 players (mean age 34±16 years, 96% men) with sudden death were reported from 67 countries; 142 players (23%) survived. A diagnosis by autopsy or definite medical reports was established in 211 cases (34%). The leading cause in players >35 years was coronary artery disease (76%) and in players ≤35 years was sudden unexplained death (SUD, 22%). In players ≤35 years the leading cause of SCD varied by region: cardiomyopathy in South America (42%), coronary artery anomaly in North America (33%) and SUD in Europe (26%). Traumatic sudden death including commotio cordis occurred infrequently (6%). Cardiopulmonary resuscitation (CPR) resulted in a survival rate of 85% with the use of an automated external defibrillator (AED) compared with 35% without.

Conclusions

Regional variation in SCD aetiology should be verified by expansion of national registries and uniform autopsy protocols. Immediate access to an AED at training and competition sites, as well as CPR training for players, coaches and staff members, is needed to improve survival from SCA.
Acute glycaemic management before, during and after exercise for cardiac rehabilitation participants with diabetes mellitus: a joint statement of the British and Canadian Associations of Cardiovascular Prevention and Rehabilitation, the International Council for Cardiovascular Prevention and Rehabilitation and the British Association of Sport and Exercise Sciences
Authors: Buckley John P , Riddell Michael , Mellor Duane , Bracken Richard M , Ross Marie-Kristelle , LaGerche Andre , Poirier Paul
Published: December 2020

Type 1 (T1) and type 2 (T2) diabetes mellitus (DM) are significant precursors and comorbidities to cardiovascular disease and prevalence of both types is still rising globally. Currently,~25% of participants (and rising) attending cardiac rehabilitation in Europe, North America and Australia have been reported to have DM (>90% have T2DM). While there is some debate over whether improving glycaemic control in those with heart disease can independently improve future cardiovascular health-related outcomes, for the individual patient whose blood glucose is well controlled, it can aid the exercise programme in being more efficacious. Good glycaemic management not only helps to mitigate the risk of acute glycaemic events during exercising, it also aids in achieving the requisite physiological and psycho-social aims of the exercise component of cardiac rehabilitation (CR). These benefits are strongly associated with effective behaviour change, including increased enjoyment, adherence and self-efficacy. It is known that CR participants with DM have lower uptake and adherence rates compared with those without DM. This expert statement provides CR practitioners with nine recommendations aimed to aid in the participant’s improved blood glucose control before, during and after exercise so as to prevent the risk of glycaemic events that could mitigate their beneficial participation.
Working accuracy of pulse oximetry in COVID-19 patients stepping down from intensive care: a clinical evaluation
Authors: Philip Keir Elmslie James , Bennett Benjamin , Fuller Silas , Lonergan Bradley , McFadyen Charles , Burns Janis , Tidswell Robert , Vlachou Aikaterini
Published: December 2020

Introduction

UK guidelines suggest that pulse oximetry, rather than blood gas sampling, is adequate for monitoring of patients with COVID-19 if CO2retention is not suspected. However, pulse oximetry has impaired accuracy in certain patient groups, and data are lacking on its accuracy in patients with COVID-19 stepping down from intensive care unit (ICU) to non-ICU settings or being transferred to another ICU.

Methods

We assessed the bias, precision and limits of agreement using 90 paired SpO2and SaO2from 30 patients (3 paired samples per patient). To assess the agreement between pulse oximetry (SpO2) and arterial blood gas analysis (SaO2) in patients with COVID-19, deemed clinically stable to step down from an ICU to a non-ICU ward, or be transferred to another ICU. This was done to evaluate whether the guidelines were appropriate for our setting.

Results

Mean difference between SaO2and SpO2(bias) was 0.4%, with an SD of 2.4 (precision). The limits of agreement between SpO2and SaO2were as follows: upper limit of 5.2% (95% CI 6.5% to 4.2%) and lower limit of −4.3% (95% CI −3.4% to −5.7%).

Conclusions

In our setting, pulse oximetry showed a level of agreement with SaO2measurement that was slightly suboptimal, although within acceptable levels for Food and Drug Authority approval, in people with COVID-19 judged clinically ready to step down from ICU to a non-ICU ward, or who were being transferred to another hospital’s ICU. In such patients, SpO2should be interpreted with caution. Arterial blood gas assessment of SaO2may still be clinically indicated.
Multicentre, prospective, randomised study comparing the diagnostic yield of colon capsule endoscopy versus CT colonography in a screening population (the TOPAZ study)
Authors: Cash Brooks D , Fleisher Mark R , Fern Steven , Rajan Elizabeth , Haithcock Robyn , Kastenberg David M , Pound David , Papageorgiou Neofytos P , Fernández-Urién Ignacio , Schmelkin Ira J , Rex Douglas K
Published: December 2020

Objective

Colon capsule endoscopy (CCE) has shown promise for colorectal neoplasia detection compared with optical colonoscopy (OC), but has not been compared with other screening tests in average risk screening patients.

Design

Patients 50 to 75 years of age (African Americans, 45–75 years) were randomised to CCE or CT colonography (CTC) and subsequent blinded OC. The primary endpoint was diagnostic yield of polyps ≥6 mm with CCE or CTC. Secondary endpoints included accuracy for size and histology, examination completeness, number/proportion of subjects with polyps and adenomas ≥6 mm and ≥10 mm, subject satisfaction and safety.

Results

From 320 enrolled subjects, data from 286 (89.4%) were evaluable. The proportion of subjects with any polyp ≥6 mm confirmed by OC was 31.6% for CCE versus 8.6% for CTC (pPr non-inferiority and superiority=0.999). The diagnostic yield of polyps ≥10 mm was 13.5% with CCE versus 6.3% with CTC (pPr non-inferiority=0.9954). The sensitivity and specificity of CCE for polyps ≥6 mm was 79.2% and 96.3% while that of CTC was 26.8% and 98.9%. The sensitivity and specificity of CCE for polyps ≥10 mm was 85.7% and 98.2% compared with 50% and 99.1% for CTC. Both tests were well tolerated/safe.

Conclusion

CCE was superior to CTC for detection of polyps ≥6 mm and non-inferior for identification of polyps ≥10 mm. CCE should be considered comparable or superior to CTC as a colorectal neoplasia screening test, although neither test is as effective as OC.

Trial registration number

ClinicalTrials.gov no: NCT02754661.
The different types of clinical audit and how to perform them
Authors: Mosedale Pam
Published: December 2020

Clinical audits should be performed regularly to highlight any areas of improvement needed in a practice. There are different types of audit for measuring different processes/systems, and they should be planned thoroughly to achieve optimal results, with the aim to continuously improve patient care.
Severity of Hypertension as a Predictor of Initiation of Dialysis among Study Participants with and without Diabetes Mellitus
Authors: Osawa Taeko , Fujihara Kazuya , Harada Yamada Mayuko , Yamamoto Masahiko , Kitazawa Masaru , Matsubayashi Yasuhiro , Iwanaga Midori , Yamada Takaho , Seida Hiroyasu , Kodama Satoru , Nakagawa Yoshimi , Shimano Hitoshi , Sone Hirohito
Published: December 2020

To determine associations between severity of hypertension and risk of starting dialysis in the presence or absence of diabetes mellitus (DM). A nationwide database with claims data on 258 874 people with and without DM aged 19-72 years in Japan was used to elucidate the impact of severity of hypertension on starting dialysis. Initiation of dialysis was determined from claims using International Classification of Diseases-10 codes and medical procedures. Using multivariate Cox modeling, we investigated the severity of hypertension to predict the initiation of dialysis with and without DM. Hypertension was significantly associated with the initiation of dialysis regardless of DM. The incidence of starting dialysis in those with systolic blood pressure (SBP) ≤119 mm Hg and DM (DM+) was almost the same as in those with SBP ≥150 mm Hg and absence of DM (DM−). In comparison with SBP ≤119 mm Hg, SBP ≥150 mm Hg significantly increased the risk of the initiation of dialysis about 2.5 times regardless of DM+ or DM−. Compared with DM− and SBP ≤119 mm Hg, the HR for DM+ and SBP ≥150 mm Hg was 6.88 (95% CI 3.66 to 12.9). Although the risks of hypertension differed only slightly regardless of the presence or absence of DM, risks for starting dialysis with DM+ and SBP ≤119 mm Hg were equivalent to DM− and SBP ≥150 mm Hg, indicating more strict blood pressure interventions in DM+ are needed to avoid dialysis. Future studies are required to clarify the cut-off SBP level to avoid initiation of dialysis considering the risks of strict control of blood pressure.
Graft Survival Effect of Hla-A Allele Matching Parathyroid Allotransplantation
Authors: Goncu Beyza , Salepcioglu Kaya Harika , Yucesan Emrah , Ersoy Yeliz Emine , Akcakaya Adem
Published: December 2020

Permanent hypoparathyroidism is an endocrine disease that is mostly associated with the disruption of the parathyroid glands during surgery. Allotransplantation is the most promising approach for treatment particularly for its cost-effective and exact curative potential. Herein our aim was to evaluate human leukocyte antigen (HLA)-A allele matching effect on clinical improvement and graft survival after parathyroid transplantation. We performed parathyroid transplantation between ABO/Rh compatible recipient and an unrelated donor who has chronic kidney disease. Preoperative immunological tests include panel reactive antibody, T-flow cytometry crossmatch, B-flow cytometry crossmatch, autoflow cytometry crossmatch, and complement-dependent cytotoxicity crossmatch tests were performed. After histopathological evaluation, half of the resected parathyroid gland cells were isolated and transplanted to the omentum surface by laparoscopy. The transplantation outcome was followed up throughout 382 days. The recipient discharged 2 days after transplantation without any complication. During follow-up, calcium and vitamin D supplementation reduced to a one-third dose; even the intact PTH levels remained low. However, clinical improvement was observed by serum calcium levels. The recipient still continues with low-dose supplementation after 382 days of post-transplantation. Parathyroid cell transplantation to the omental tissue is the most promising option even with only one allele matching for patients with using lifelong high-dose supplementation. Clinical improvements and long-term effect of HLA-A allele matching should be evaluated with more studies and in larger cohorts as well.
Current Immunotherapy in Gastrointestinal Malignancies a Review
Authors: Singh Dahiya Dushyant , Kichloo Asim , Singh Jagmeet , Albosta Michael , Lekkala Manidhar
Published: December 2020

Immunotherapy is an extremely important breakthrough and an exciting new modality of treatment for a wide spectrum of cancers. It is focused around developing agents to stimulate or suppress the immune system, in a specific manner, to fight off a wide spectrum of diseases, particularly cancers. Traditional therapies available for the treatment of cancers include surgical intervention, chemotherapy, radiation therapy or a combination of these, which tend to be very non-specific. However, immunotherapy shows a stark difference from conventional therapy, in fact, that it has a high level of specificity for the tumor-specific antigens. The recent success of cancer immunotherapies in clinical trials is slowly revolutionizing the landscape for cancer therapy. The US Food and Drug Administration has approved numerous agents, after clinical trials showed promising results, for the treatment of multiple cancers. The role of immunotherapy in gastrointestinal cancers has also been very promising, particularly in patients with advanced metastatic disease or malignancies refractory to initial treatment. In this review of literature, we detail and discuss the immunotherapy agents approved for the treatment of GI cancers and glance at the future of immunotherapy for patients with these cancers.
Anticoagulation and Antiplatelet Therapy in Contact Sports: Is it Career Limiting?
Authors: Kichloo Asim , Amir Rawan , Wani Farah , Randhawa Sukhbir , Rudd Benjamin , Rechlin David
Published: December 2020

Medical conditions requiring treatment with anticoagulation (AC) or antiplatelet therapy have a huge burden on the average patient, but such conditions can have catastrophic effects on the careers of young, rising athletes, in particular those involved in contact sports at a professional level. Contact sports are defined as sports in which body-to-body contact is expected as part of the game such as football, basketball, soccer and hockey. The rates of injuries in these sports are high increasing the likelihood of bleeding event on AC. The main etiologies requiring AC and antiplatelets in athletes are venous thromboembolism and coronary artery disease, respectively. To date, there are no clear medical guidelines on the management of such conditions in athletes. Herein we review the traditional approach to treating such conditions afflicting athletes as well as more recently modified approaches to answer the ultimate question: should anticoagulation or antiplatelet therapy in contact sports be career limiting?