bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of the Fracture Location by Tensile Tests of Gray Cast Iron Based on the Dimensional Changes of Graphite Flakes
Authors: Tada Naoya , Uemori Takeshi , Sakamoto Junji
Published: August 2020

Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high performance-to-cost ratio. On the other hand, weak graphite flakes present in gray cast iron serve as stress concentrators and adversely affect the material strength. Therefore, it is crucial to examine the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, tensile tests on gray cast iron were carried out using a plate specimen and observed by scanning electron microscopy, and the microscopic deformation was observed on the specimen surface. Particularly, the change in the size of graphite flakes during the tensile tests was examined, and the observed trend was discussed. The experimental results reveal that the dimensional changes in the graphite flakes vary in the observed area and that the final fracture occurs in an area where a large dimensional change is observed, suggesting that the fracture location or critical parts of gray cast iron can be predicted from the dimensional changes of the graphite flakes at an early stage of deformation.
Parametric Investigation of the Flow-Sound Interaction Mechanism for Single Cylinders in Cross-Flow
Authors: Afifi Omar , Mohany Atef
Published: August 2020

Flow-excited acoustic resonance is a design concern in many industrial applications. If not treated, it may lead to excessive vibrational loads, which could subsequently result in premature structural failure of critical equipment. For the case of tube bundles in heat exchangers, several acoustic damping criteria were proposed in the literature to predict the occurrence of resonance excitation. However, these criteria, in some cases, are not reliable in differentiating between the resonant and nonresonant cases. A primary reason for that is the geometrical differences between reduced scale models and full-scale tube bundles, and their effect on the flow-sound interaction mechanism. Therefore, the effect of two geometrical aspects, namely, the duct height and the cylinder diameter, on the self-excited acoustic resonance for single cylinders in cross-flow is experimentally investigated in this work. Changing the duct height changes the natural frequency of the excited acoustic modes and the duct's acoustic damping and radiation losses. Changing the cylinder diameter changes the flow velocity at frequency coincidence, the pressure drop, and Reynolds number. It is found that increasing the duct height decreases the acoustic impedance, which makes the system more susceptible to resonance excitation. This, in turn, changes the magnitude of the acoustic pressure at resonance, even for cases where the dynamic head of the flow is kept constant. The acoustic attenuation due to visco-thermal losses is quantified theoretically using Kirchhoff's acoustical damping model, which takes into account the geometrical aspects of the different ducts. Results from the experiments are compared with the acoustic damping criteria from the literature for similar cases. It is revealed that the height of the duct is an important parameter that should be included in damping criteria proposed for tube bundles of heat exchangers, as it controls the acoustic damping and radiation losses of the system, which have been over-looked in the past.
Preliminary Material Evaluation of Flax Fibers for Prosthetic Socket Fabrication
Authors: Monette Dominic , Dumond Patrick , Chikhaoui Inès , Nichols Paul , Lemaire Edward D.
Published: August 2020

Composite prosthetic sockets are typically made of fiberglass or carbon fiber. These fibers have good mechanical properties, but relatively poor vibration damping. Flax fibers are claimed to have exceptional vibration damping properties, with the added benefit of being a natural renewable resource and a cost-effective alternative to synthetic fibers. Flax fibers could prove beneficial for prosthetic sockets, providing lightweight sockets that reduce vibrations transmitted to the body during movement. This research used impact testing (impulse hammer and custom drop tower) on flat and socket shaped composite samples to evaluate composite layer options. Sample vibration dissipation was measured by a combination of accelerometers, load cells, and a dynamometer. Composite sockets made purely of flax fibers were lighter and more efficient at damping vibrations, reducing the amplification of vibrations by a factor of nearly four times better than sockets made purely of carbon fiber. However, the bending stiffness, elastic moduli, and flexural strength of flax sockets fabricated using the traditional socket manufacturing method were found to be ten times lower than theoretical values of flax composites found in the literature. By increasing fiber volume fraction when using the traditional socket manufacturing method, the composite's mechanical properties, namely, vibration damping, could improve and flax fiber benefits could be explored further.
Heat Transfer Enhancement in Pool Boiling of Distilled Water Using Gridded Metal Surface With Protrusions Over Microporous-Coated Surface
Authors: Chauhan Vidushi , Kumar Manoj , Patil Anil Kumar
Published: August 2020

The nucleate pool is a useful technique of heat dissipation in a variety of thermal applications. This study investigates the effect of the gridded metal surface (GMS) with and without protrusions on the heat transfer from a surface maintained at a temperature above the saturation temperature of water. The experimental data have been collected pertaining to boiling heat transfer at atmospheric pressure by varying the grid size of gridded metal surface with protrusions from 6 mm to 22.5 mm placed over a boiling surface having microporous coating. The mean particle diameter of coating is varied as 11, 24, and 66 μm during the experimentation. It is observed that the increase in the boiling heat transfer coefficient of the aluminum disk with GMS with protrusions of grid size 11.5 mm compared to that of the smooth boiling surface is found to be 10.7%. Furthermore, the effect of GMS having protrusions with coated surface on the heat transfer is studied. The results showed that by using GMS having protrusions and with coated surface, the heat transfer is further enhanced. The boiling heat transfer coefficient obtained in case of GMS with protrusions (grid size = 11.5 mm) and microporous-coated surface (dm = 66 μm) shows the maximum enhancement of 39.93% in comparison to the smooth surface.
Ballistic-Diffusive Heat Conduction in Thin Films by Phonon Monte Carlo Method: Gray Medium Approximation Versus Phonon Dispersion
Authors: Li Han-Ling , Shiomi Junichiro , Cao Bing-Yang
Published: August 2020

The gray medium approximation treating all phonons with an averaged and representative mean-free-path (MFP) is an often used method in analyzing ballistic-diffusive heat conduction at nanoscale. However, whether there exists a reasonable value of the average MFP which effectively represents the entire spectrum of modal MFPs remains unclear. In this paper, phonon Monte Carlo (MC) method is employed to study the effects of the gray medium approximation on ballistic-diffusive heat conduction in silicon films by comparing with dispersion MC simulations. Four typical ways for calculating the average MFP with gray medium approximation are investigated. Three of them are based on the weighted average of the modal MFPs, and the remaining one is based on the weighted average of the reciprocals of the modal MFPs. The first three methods are found to be good at predicting effective thermal conductivity and heat flux distribution, but have difficulties in temperature profile, while the last one performs better for temperature profile than effective thermal conductivity and heat flux distribution. Therefore, none of the average MFPs can accurately characterize all the features of ballistic-diffusive heat conduction for the gray medium approximation. Phonon dispersion has to be considered for the accurate thermal analyses and modeling of ballistic-diffusive heat transport. Our work could be helpful for further understanding of phonon dispersion and more careful use of the gray medium approximation.
Effect of Material Strength on Ductile Failure of Steel in Pressure Vessel Design
Authors: Baghous N. , Barsoum I.
Published: August 2020

Pressure vessels and their components are commonly designed with the ASME Boiler and Pressure Vessel Codes. One of the requirements when pursuing the design by analysis route is to design these equipment against ductile local failure criterion provided in the codes. However, the ductile local failure criterion in the ASME codes only accounts for the stress triaxiality (T) as a stress state measure. Recent work has shown that ductile failure highly depends on the stress state characterized by both T and the Lode parameter L, which is related to the third deviatoric stress invariant. In this study, the effect of stress state characterized by both T and L is investigated for six different steel grades with different material strength levels. To establish the ductile failure loci for the six steel grades with respect to T and L, experiments were conducted on two different specimen geometries. The L parameter is controlled by the specimen configuration, where the round notched bar specimen corresponds to axisymmetric tensile conditions (L = −1) and the flat notched specimen corresponds to plane strain loading conditions (L = 0), whereas T is controlled by introducing a notch at the center of the specimens. A Lode sensitivity parameter (LS) is defined based on the experimental results and revealed that the steel grades with ultimate strength higher than a certain threshold value (450 MPa) exhibit sensitivity to the Lode parameter. The Lode sensitivity was quantified, and the results showed that the LS increases with increase in the ultimate strength of the steel grade. The results were incorporated to enhance the original ASME local failure criterion by accounting for T, L, and LS to accurately assess ductile failure in high-strength steels. The application of the enhanced failure locus in a design analysis of a pressure vessel made of a high-strength steel grade is demonstrated, which showed that the original ASME criterion, as compared to the enhanced criterion in this study, is not capable of predicting ductile failure and hence rendering a rather nonconservative design. It is concluded that the enhanced local failure criterion is recommended to be used for the design of pressure vessels and their components made of steel grades with an ultimate strength higher than the threshold value.
Vacuum outgassing characteristics of unpigmented 3D printed polymers coated with atomic layer deposited alumina
Authors: Bihari Nupur , Heikkinen Ismo T. S. , Marin Giovanni , Ekstrum Craig , Mayville Pierce J. , Oberloier Shane , Savin Hele , Karppinen Maarit , Pearce Joshua M.
Published: August 2020

3D printing offers enormous potential for fabricating custom equipment for space and vacuum systems, but in order to do this at low costs, polymers are necessary. Historically, polymers have not been suitable for these applications because of outgassing, but if coated with a conformal, inorganic film introduced with atomic layer deposition (ALD), then outgassing can be reduced. Previous work on coating ALD layers showed promise with heavily outgassing carbon black containing 3D printed polymers. In this study, ALD aluminum oxide and a commercially available vacuum sealant resin were used to coat clear, acrylonitrile butadiene styrene, polycarbonate, and polypropylene. Characterization of the films included spectroscopic ellipsometry for thickness, microstructure analysis with scanning electron microscopy, chemical analysis with energy-dispersive x-ray spectroscopy, and residual gas analysis to study relative change in outgassing. ALD-coated samples registered lower pressures than the resin-coated ones. The results showed that the ALD coatings could effectively inoculate unpigmented 3D printed plastics, which could be used in contamination-sensitive environments such as semiconductor processing systems and space environments.
Investigation of organic precursors and plasma mixtures allowing control of carbon passivation when etching HgCdTe in hydrocarbon-based inductively coupled plasmas
Authors: Piet Jordan , Faider Wilfrid , Girard Aurélie , Boulard François , Cardinaud Christophe
Published: August 2020

Our interest in introducing oxygen and/or nitrogen atoms in CH4/H2/Ar plasma mixtures by means of organic precursors in the place of CH4 or by partly substituting O2 or N2O for H2 and thereby controlling carbon deposition and surface passivation when etching HgCdTe under low substrate bias conditions is investigated in this study. Using in situ ellipsometry, in situ x-ray photoelectron spectroscopy, atomic force microscopy, and secondary electron microscopy (SEM), we show that nitromethane as a precursor and N2O substitution are attractive alternatives for the following: the absence of deposition although no bias is applied, equivalent postetch surface composition, and comparable performances in terms of etch rate and surface roughness for the latter. Such an approach could provide the soft dry etching conditions needed to reduce the pixel pitch of HgCdTe infrared photovoltaic detectors. The mechanisms that allow suppressing carbon deposition upon O2 or N2O substitution in CH4/H2/Ar plasmas are studied by combining plasma diagnostics (optical emission spectroscopy, actinometry, and ion flux measurements) and surface characterizations. First, using Si as a reference substrate, it is shown that deposition is suppressed whenever the O2 and N2O flow rate is half and twice that of CH4, respectively. Moreover, the study reveals that oxygen is the true etch reactant controlling the competition between film growth and etching in both substituted processes, whereas incorporation of nitrogen in the film upon N2O substitution favors its etching kinetics simultaneously. Second, on HgCdTe, deposition of a hydrocarbonitride film is observed at a low N2O/CH4 ratio (∼0.6). SEM and SEM-energy dispersive x-ray spectroscopy imaging suggest that the film nucleates and grows preferentially on regions where the Cd removal mechanisms happen to be less efficient. At a high N2O/CH4 ratio (∼4), oxidation of the HgCdTe surface is observed.
Could Relative Movement Between the Adductor Muscles and the Skin Invalidate Surface Electromyography Measurement?
Authors: Elsais Walaa M. , Preece Stephen J. , Jones Richard K. , Herrington Lee
Published: August 2020

The superficial hip adductor muscles are situated in close proximity to each other. Therefore, relative movement between the overlying skin and the muscle belly could lead to a shift in the position of surface electromyography (EMG) electrodes and contamination of EMG signals with activity from neighboring muscles. The aim of this study was to explore whether hip movements or isometric contraction could lead to relative movement between the overlying skin and 3 adductor muscles: adductor magnus, adductor longus, and adductor gracilis. The authors also sought to investigate isometric torque–EMG relationships for the 3 adductor muscles. Ultrasound measurement showed that EMG electrodes maintained a position which was at least 5 mm within the muscle boundary across a range of hip flexion–extension angles and across different contraction levels. The authors also observed a linear relationship between torque and EMG amplitude. This is the first study to use ultrasound to track the relative motion between skin and muscle and provides new insight into electrode positioning. The findings provide confidence that ultrasound-based positioning of EMG electrodes can be used to derive meaningful information on output from the adductor muscles and constitute a step toward recognized guidelines for surface EMG measurement of the adductors.
An Education for Life: The Process of Learning the Alexander Technique
Authors: Woods Charlotte , Glover Lesley , Woodman Julia
Published: August 2020

The Alexander technique is an educational self-development self-management method with therapeutic benefits. The primary focus of the technique is learning about the self, conceptualized as a mind–body unity. Skills in the technique are gained experientially, including through hands-on and spoken guidance from a certified Alexander teacher, often using everyday movement such as walking and standing. In this article the authors summarize key evidence for the effectiveness of learning the Alexander technique and describe how the method was developed. They attempt to convey a sense of the unique all-encompassing and fundamental nature of the technique by exploring the perspectives of those engaged in teaching and learning it and conclude by bringing together elements of this account with relevant strands of qualitative research to view this lived experience in a broader context.
Potential Mechanisms of the Alexander Technique: Toward a Comprehensive Neurophysiological Model
Authors: Cacciatore Timothy W. , Johnson Patrick M. , Cohen Rajal G.
Published: August 2020

The Alexander technique (AT) has been practiced for over 125 years. Despite evidence of its clinical utility, a clear explanation of how AT works is lacking, as the foundational science needed to test the underlying ideas has only recently become available. The authors propose that the core changes brought about by Alexander training are improvements in the adaptivity and distribution of postural tone, along with changes in body schema, and that these changes underlie many of the reported benefits. They suggest that AT alters tone and body schema via spatial attention and executive processes, which in turn affect low-level motor elements. To engage these pathways, AT strategically engages attention, intention, and inhibition, along with haptic communication. The uniqueness of the approach comes from the way these elements are woven together. Evidence for the contribution of these elements is discussed, drawing on direct studies of AT and other relevant modern scientific literature.
Altered 3D chromatin structure permits inversional recombination at the
IgH
locus
Authors: Qiu Xiang , Ma Fei , Zhao Mingming , Cao Yaqiang , Shipp Lillian , Liu Angela , Dutta Arun , Singh Amit , Braikia Fatima Zohra , De Supriyo , Wood William H. , Becker Kevin G. , Zhou Weiqiang , Ji Hongkai , Zhao Keji , Atchison Michael L. , Sen Ranjan
Published: August 2020

Different mechanisms govern the first and second steps of
IgH
gene recombination.
Viruses harness YxxØ motif to interact with host AP2M1 for replication: A vulnerable broad-spectrum antiviral target
Authors: Yuan Shuofeng , Chu Hin , Huang Jingjing , Zhao Xiaoyu , Ye Zi-Wei , Lai Pok-Man , Wen Lei , Cai Jian-Piao , Mo Yufei , Cao Jianli , Liang Ronghui , Poon Vincent Kwok-Man , Sze Kong-Hung , Zhou Jie , To Kelvin Kai-Wang , Chen Zhiwei , Chen Honglin , Jin Dong-Yan , Chan Jasper Fuk-Woo , Yuen Kwok-Yung
Published: August 2020

Host AP2M1 protein is exploited by diverse pathogenic viruses via their YxxØ protein motif during viral replication cycle.
Transiently chaotic simulated annealing based on intrinsic nonlinearity of memristors for efficient solution of optimization problems
Authors: Yang Ke , Duan Qingxi , Wang Yanghao , Zhang Teng , Yang Yuchao , Huang Ru
Published: August 2020

This work shows a memristive optimizer based on transient chaos, which is able to solve optimization problems efficiently.
Self-targeting, zwitterionic micellar dispersants enhance antibiotic killing of infectious biofilms—An intravital imaging study in mice
Authors: Tian Shuang , Su Linzhu , Liu Yong , Cao Jingjing , Yang Guang , Ren Yijin , Huang Fan , Liu Jianfeng , An Yingli , van der Mei Henny C. , Busscher Henk J. , Shi Linqi
Published: August 2020

Zwitterionic micelles find their own path through the body to disperse an infectious biofilm and enhance antibiotic efficacy.
Decades-old model of slow adaptation in sensory hair cells is not supported in mammals
Authors: Caprara Giusy A. , Mecca Andrew A. , Peng Anthony W.
Published: August 2020

Decades-old model of slow adaptation in sensory hair cells of the auditory and vestibular systems requires revamp.
3D bioprinting spatiotemporally defined patterns of growth factors to tightly control tissue regeneration
Authors: Freeman Fiona E. , Pitacco Pierluca , van Dommelen Lieke H. A. , Nulty Jessica , Browe David C. , Shin Jung-Youn , Alsberg Eben , Kelly Daniel J.
Published: August 2020

Spatiotemporal delivery of VEGF and BMP-2 from 3D bioprinted implants enhances angiogenesis and subsequent bone regeneration.
Evidence that the ProPerDP method is inadequate for protein persulfidation detection due to lack of specificity
Authors: Fan Kaili , Chen Zhigang , Liu Huaiwei
Published: August 2020

The specificity of ProPerDP method is too low for analysis of protein persulfidation.
Easing the Monte Carlo sign problem
Authors: Hangleiter Dominik , Roth Ingo , Nagaj Daniel , Eisert Jens
Published: August 2020

Systematic easing via efficiently computable measures can make quantum matter with a sign problem amenable to Monte Carlo methods.
A novel mouse model of chronic suppurative otitis media and its use in preclinical antibiotic evaluation
Authors: Khomtchouk Kelly M. , Kouhi Ali , Xia Anping , Bekale Laurent Adonis , Massa Solange M. , Sweere Jolien M. , Pletzer Daniel , Hancock Robert E. , Bollyky Paul L. , Santa Maria Peter L.
Published: August 2020

A novel mouse model of chronic ear infections is used to investigate antibiotic failure in humans.
Tissue Tropisms and Transstadial Transmission of a
Rickettsia
Endosymbiont in the Highland Midge, Culicoides impunctatus (Diptera: Ceratopogonidae)
Authors: Pilgrim Jack , Siozios Stefanos , Baylis Matthew , Hurst Gregory D. D.
Published: August 2020

Microbial symbionts of disease vectors have garnered recent attention due to their ability to alter vectorial capacity. Their consideration as a means of arbovirus control depends on symbiont vertical transmission, which leads to spread of the bacteria through a population. Previous work has identified a
Rickettsia
symbiont present in several species of biting midges (
Culicoides
spp.), which transmit bluetongue and Schmallenberg arboviruses. However, symbiont transmission strategies and host effects remain underexplored. In this study, we describe the presence of
Rickettsia
in the ovarian suspensory ligament of
Culicoides impunctatus
. Infection of this organ suggests the connective tissue surrounding developing eggs is important for ensuring vertical transmission of the symbiont in midges and possibly other insects. Additionally, our results indicate
Rickettsia
localization in the fat body of
Culicoides impunctatus
. As the arboviruses spread by midges often replicate in the fat body, this location implies possible symbiont-virus interactions to be further investigated.
Novel Selective Inhibition of Lactobacillus iners by
Lactobacillus
-Derived Bacteriocins
Authors: Nilsen Trine , Swedek Iwona , Lagenaur Laurel A. , Parks Thomas P.
Published: August 2020

Lactobacillus iners
is a prevalent species of the vaginal microbiome, but unlike other major vaginal
Lactobacillus
species, it is not considered protective against BV and can coexist with BV-associated bacteria.
L. iners
is generally the first
Lactobacillus
species to emerge following the treatment of BV with metronidazole, and mounting evidence suggests that it may contribute to the onset and maintenance of vaginal dysbiosis. The discovery of highly potent bacteriocins that selectively kill
L. iners
while sparing protective vaginal lactobacilli may provide novel pharmacological tools to better understand the roles of this enigmatic bacterium in vaginal ecology and potentially lead to new and improved therapies for dysbiosis-related conditions such as BV.
SMAC Mimetic Plus Triple-Combination Bispecific HIVxCD3 Retargeting Molecules in SHIV.C.CH505-Infected, Antiretroviral Therapy-Suppressed Rhesus Macaques
Authors: Dashti Amir , Waller Chevaughn , Mavigner Maud , Schoof Nils , Bar Katharine J. , Shaw George M. , Vanderford Thomas H. , Liang Shan , Lifson Jeffrey D. , Dunham Richard M. , Ferrari Guido , Tuyishime Marina , Lam Chia-Ying K. , Nordstrom Jeffrey L. , Margolis David M. , Silvestri Guido , Chahroudi Ann
Published: August 2020

The most significant barrier to an HIV-1 cure is the existence of the latently infected viral reservoir that gives rise to rebound viremia upon cessation of ART. Here, we tested a novel combination approach of latency reversal with AZD5582 and clearance with bispecific HIVxCD3 DART molecules in SHIV.C.CH505-infected, ART-suppressed rhesus macaques. We demonstrate that the DART molecules were not capable of clearing infected cells
in vivo
, attributed to the lack of quantifiable latency reversal in this model with low levels of persistent SHIV DNA prior to intervention as well as DART molecule immunogenicity.
Molecular Characterization of Influenza C Viruses from Outbreaks in Hong Kong SAR, China
Authors: Daniels Rodney S. , Tse Herman , Ermetal Burcu , Xiang Zheng , Jackson Deborah J. , Guntoro Jeremy , Nicod Jérôme , Stewart Aengus , Cross Karen J. , Hussain Saira , McCauley John W. , Lo Janice
Published: August 2020

Influenza C virus infection of humans is common, and reinfection can occur throughout life. While symptoms are generally mild, severe disease cases have been reported, but knowledge of the virus is limited, as little systematic surveillance for influenza C virus is conducted and the virus cannot be studied by classical virologic methods because it cannot be readily isolated in laboratories. A combination of systematic surveillance in Hong Kong SAR, China, and new gene sequencing methods has been used in this study to assess influenza C virus evolution and provides evidence for a 2-year cycle of disease outbreaks. The results of studies like that reported here are key to developing an understanding of the impact of influenza C virus infection in humans and how virus evolution might be associated with epidemics.
Mesoproterozoic–Early Cretaceous provenance and paleogeographic evolution of the Northern Rocky Mountains: Insights from the detrital zircon record of the Bridger Range, Montana, USA
Authors: Ronemus Chance B. , Orme Devon A. , Campbell Saré , Black Sophie R. , Cook John
Published: August 2020

The Bridger Range of southwest Montana, USA, preserves one of the most temporally extensive sedimentary sections in North America, with strata ranging from Mesoproterozoic to Cretaceous in age. This study presents new detrital zircon geochronologic data from eight samples collected across this mountain range. Multidimensional scaling and non-negative matrix factorization statistical analyses are used to quantitatively unmix potential sediment sources from these and 54 samples compiled from previous studies on regional correlative strata. We interpret these sources based on reference data from preserved strata with detrital zircon signatures likely representative of ancient sediment sources. We link these sources to their sinks along sediment dispersal pathways interpreted using available paleogeographic constraints. Our results show that Mesoproterozoic strata in southwest Montana contain detritus derived from the nearby craton exposed along the southern margin of the fault-bounded Helena Embayment. Middle Cambrian strata were dominated by the recycling of local sources eroded during the development of the Great Unconformity. In Devonian–Pennsylvanian time, provenance in southwest Montana shifted to more distal sources along the northeastern to southeastern margins of Laurentia, but more western basins received detritus from outboard sources along a tectonically complicated margin. By the Late Jurassic, provenance in the developing retroarc foreland basin system was dominated by Cordilleran magmatic arcs and fold-thrust belt sources to the west. Eastward propagation of the fold-thrust belt caused recycling of Paleozoic and Jurassic detritus into the foreland basin to dominate by the Early Cretaceous.
Ocean acidification during the early Toarcian extinction event: Evidence from boron isotopes in brachiopods
Authors: Müller Tamás , Jurikova Hana , Gutjahr Marcus , Tomašových Adam , Schlögl Jan , Liebetrau Volker , Duarte Luís v. , Milovský Rastislav , Suan Guillaume , Mattioli Emanuela , Pittet Bernard , Eisenhauer Anton
Published: August 2020

The loss of carbonate production during the Toarcian Oceanic Anoxic Event (T-OAE, ca. 183 Ma) is hypothesized to have been at least partly triggered by ocean acidification linked to magmatism from the Karoo-Ferrar large igneous province (southern Africa and Antarctica). However, the dynamics of acidification have never been directly quantified across the T-OAE. Here, we present the first record of temporal evolution of seawater pH spanning the late Pliensbachian and early Toarcian from the Lusitanian Basin (Portugal) reconstructed on the basis of boron isotopic composition (δ11B) of brachiopod shells. δ11B declines by ∼1‰ across the Pliensbachian-Toarcian boundary (Pl-To) and attains the lowest values (∼12.5‰) just prior to and within the T-OAE, followed by fluctuations and a moderately increasing trend afterwards. The decline in δ11B coincides with decreasing bulk CaCO3 content, in parallel with the two-phase decline in carbonate production observed at global scales and with changes in pCO2 derived from stomatal indices. Seawater pH had declined significantly already prior to the T-OAE, probably due to the repeated emissions of volcanogenic CO2. During the earliest phase of the T-OAE, pH increased for a short period, likely due to intensified continental weathering and organic carbon burial, resulting in atmospheric CO2 drawdown. Subsequently, pH dropped again, reaching the minimum in the middle of the T-OAE. The early Toarcian marine extinction and carbonate collapse were thus driven, in part, by ocean acidification, similar to other Phanerozoic events caused by major CO2 emissions and warming.
Precipitation and aridity constraints from paleolakes on early Mars
Authors: Stucky de Quay Gaia , Goudge Timothy A. , Fassett Caleb I.
Published: August 2020

The ancient climate of Mars remains an enigma despite the abundance of in situ and remote-sensing data revealing hydrological activity in the past. The crux of this debate—informed by geomorphic studies, chemical alteration observations, and numerical climate models—is the amount, distribution, and nature of surface water and precipitation (i.e., rain vs. snow). Here, we combined measurements of 96 open- and closed-basin lakes with simple hydrological balances to constrain catchment-averaged precipitation, PT, integrated over a given runoff episode of indeterminate length during early Mars history. We included 13 systems containing both open- and closed-basin lakes, providing fully bounded precipitation estimates (coupled systems). We show that, on average, PT was ≳4 m and ≲159 m; however, local precipitation was spatially variable and consistent with a complex, planetwide climate. Aridity indexes of open-basin lakes indicate some regions may have been at least as humid as semiarid terrestrial environments. Our results offer widely distributed, quantitative hydro-climate constraints that can be used to test paleoclimate model scenarios, working toward bridging the gap between geological observations and climate theory for early Mars.
Service evaluation of laceration risk using trainer adrenaline auto-injectors
Authors: Pike Louise Charlotte , Tuthill David
Published: August 2020

Objective

Anaphylaxis is a severe, potentially fatal allergic reaction best treated with intramuscular epinephrine via epinephrine auto-injectors (AAIs). Our published concerns over laceration injuries to young children associated with AAIs led to this service evaluation of the two administration methods: swing and jab (S&J) and place and press (P&P), to determine potential laceration risk.

Design

A trainer EpiPen was used with facepaint placed in the needle indentation which would record the length of movement of the AAI. The two different methods ‘administered’ were alternated. Children were asked to move their leg to simulate a withdrawal reaction. Age, whether they moved, and length of paint mark were recorded.

Setting

Outpatients waiting area in Noah’s Ark Children’s Hospital, Cardiff.

Participants

Children aged 5–11 with no prior knowledge of AAI use.

Intervention

No intervention was implemented.

Results

135 children (mean age 8 years; range 5–11 years) were asked to participate; measurements were taken from 100 children. 50 children moved for one or both methods. For those that moved, S&J mean paint length=8.3 mm (SD 17.4, 95% CI 3.4 to 13.3), P&P mean=3.5 mm (SD 11.0, 95% CI 0.4 to 6.6). Mean difference between methods was 4.8 mm (SD 10.1, 95% CI 1.9 to 7.7). Slightly more children moved for S&J (44) compared with 38 for P&P.

Conclusions

S&J produces more movement and longer paint marks than P&P. The risk of laceration when administering an EpiPen to young children may be lower by using the more controlled P&P. We feel it is advisable to teach P&P instead in children below 11 years of age.
The era of artificial intelligence and virtual reality: transforming surgical education in ophthalmology
Authors: Bakshi Shaunak K , Lin Shawn R , Ting Daniel Shu Wei , Chiang Michael F , Chodosh James
Published: August 2020

Training the modern ophthalmic surgeon is a challenging process. Microsurgical education can benefit from innovative methods to practice surgery in low-risk simulations, assess and refine skills in the operating room through video content analytics, and learn at a distance from experienced surgeons. Developments in emerging technologies may allow us to pursue novel forms of instruction and build on current educational models. Artificial intelligence, which has already seen numerous applications in ophthalmology, may be used to facilitate surgical tracking and evaluation. Within immersive technology, growth in the space of virtual reality head-mounted displays has created intriguing possibilities for operating room simulation and observation. Here, we explore the applications of these technologies and comment on their future in ophthalmic surgical education.
Aerobic performance among healthy (non-asthmatic) adults using beta2-agonists: a systematic review and meta-analysis of randomised controlled trials
Authors: Riiser Amund , Stensrud Trine , Stang Julie , Andersen Lars Bo
Published: August 2020

Objective

To examine the effect of beta2-agonists on aerobic performance in healthy, non-asthmatic study participants.

Design

Systematic review and meta-analysis.

Eligibility criteria

We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials published until December 2019. Studies examining the effect of beta2-agonists on maximal physical performance lasting longer than 1 min were included in the meta-analysis. Data are presented as standardised difference in mean (SDM) with 95% CI.

Results

The present meta-analysis includes 47 studies. The studies comprise 607 participants in cross-over trials, including 99 participants in three-way cross-over trials and 27 participants in a four-way cross-over trial. Seventy-three participants were included in parallel trials. Beta2-agonists did not affect aerobic performance compared with placebo (SDM 0.051, 95% CI −0.020 to 0.122). The SDM for the included studies was not heterogeneous (I2=0%, p=0.893), and the effect was not related to type of beta2-agonist, dose, administration route, duration of treatment or performance level of participants. Beta2-agonists had no effect on time trial performance, time to exhaustion or maximal oxygen consumption (p<0.218).

Conclusion/implication

The present study shows that beta2-agonists do not affect aerobic performance in non-asthmatic subjects regardless of type, dose, administration route, duration of treatment or performance level of participants. The results of the present study should be of interest to WADA and to anyone who is interested in equal opportunities in competitive sports.

Systematic review registration

PROSPERO CRD42018109223.
Changes in medication administration error rates associated with the introduction of electronic medication systems in hospitals: a multisite controlled before and after study
Authors: Westbrook Johanna I , Sunderland Neroli S , Woods Amanda , Raban Magdalena Z , Gates Peter , Li Ling
Published: August 2020

Background

Electronic medication systems (EMS) have been highly effective in reducing prescribing errors, but little research has investigated their effects on medication administration errors (MAEs).

Objective

To assess changes in MAE rates and types associated with EMS implementation.

Methods

This was a controlled before and after study (three intervention and three control wards) at two adult teaching hospitals. Intervention wards used an EMS with no bar-coding. Independent, trained observers shadowed nurses and recorded medications administered and compliance with 10 safety procedures. Observational data were compared against medication charts to identify errors (eg, wrong dose). Potential error severity was classified on a 5-point scale, with those scoring ≥3 identified as serious. Changes in MAE rates preintervention and postintervention by study group, accounting for differences at baseline, were calculated.

Results

7451 administrations were observed (4176 pre-EMS and 3275 post-EMS). At baseline, 30.2% of administrations contained ≥1 MAE, with wrong intravenous rate, timing, volume and dose the most frequent. Post-EMS, MAEs decreased on intervention wards relative to control wards by 4.2 errors per 100 administrations (95% CI 0.2 to 8.3; p=0.04). Wrong timing errors alone decreased by 3.4 per 100 administrations (95% CI 0.01 to 6.7; p<0.05). EMS use was associated with an absolute decline in potentially serious MAEs by 2.4% (95% CI 0.8 to 3.9; p=0.003), a 56% reduction in the proportion of potentially serious MAEs. At baseline, 74.1% of administrations were non-compliant with ≥1 of 10 procedures and this rate did not significantly improve post-EMS.

Conclusions

Implementation of EMS was associated with a modest, but significant, reduction in overall MAE rate, but halved the proportion of MAEs rated as potentially serious.
‘Sometimes you are forced to play God…’: a qualitative study of healthcare worker experiences of using continuous positive airway pressure in newborn care in Kenya
Authors: Nabwera Helen M , Wright Jemma L , Patil Manasi , Dickinson Fiona , Godia Pamela , Maua Judith , Sammy Mercy K , Naimoi Bridget C , Warfa Osman H , Dewez Juan Emmanuel , Murila Florence , Manu Alexander , Smith Helen , Mathai Matthews
Published: August 2020

​Objective

To explore the experiences of using continuous positive airway pressure (CPAP) in newborn care among healthcare workers in Kenya, and to identify factors that would promote successful scale-up.

​Design and setting

A qualitative study using key informant interviews and focus group discussions, based at secondary and tertiary level hospitals in Kenya.

​Participants

Healthcare workers in the newborn units providing CPAP.

​Primary and secondary outcome measure

Facilitators and barriers of CPAP use in newborn care in Kenya.

​Results

16 key informant interviews and 15 focus group discussions were conducted across 19 hospitals from September 2017 to February 2018. Main barriers reported were: (1) inadequate infrastructure to support the effective delivery of CPAP, (2) shortage of skilled staff rendering it difficult for the available staff to initiate or monitor infants on CPAP and (3) inadequate knowledge and training of staff that inhibited the safe care of infants on CPAP. Key facilitators reported were positive patient outcomes after CPAP use that increased staff confidence and partnership with caregivers in the management of newborns on CPAP. Healthcare workers in private/mission hospitals had more positive experiences of using CPAP in newborn care as the relevant support and infrastructure were available.

​Conclusion

CPAP use in newborn care is valued by healthcare workers in Kenya. However, we identified key challenges that threaten its safe use and sustainability. Further scale-up of CPAP in newborn care should ensure that staff members have ready access to optimal training on CPAP and that there are enough resources and infrastructure to support its use.

Ethics

This study was approved through the appropriate ethics committees in Kenya and the UK (see in text) with written informed consent for each participant.
Health programmes and services addressing the prevention and management of infectious diseases in persons who inject drugs in Canada: a systematic integrative review protocol
Authors: Alvarez Elizabeth , Joshi Siddharth , Lokker Cynthia , Wang Annie , Pavalagantharajah Sureka , Qiu Yun , Sidhu Hargun , Mbuagbaw Lawrence , Qutob Majdi , Henedi Alia , Levine Mitchell , Lennox Robin , Tarride Jean-Eric , Kalina Dale
Published: August 2020

Introduction

Injection drug use (IDU) and intravenous drug use (IVDU) are of concern to the people using drugs, their families and health systems. One of the complications of IDU/IVDU is the risk of infection. Clinical experience has shown that persons who inject drugs (PWID) are hospitalised and re-hospitalised frequently. In Canada there are sparse data about the reasons for which PWID are admitted to hospital and their health trajectories, especially for infectious diseases. There are special concerns regarding PWID with infections who leave the hospital against medical advice and those who leave with a peripherally inserted central catheter line in place for administration of long-term antibiotics or other therapies. Improving our understanding of current programmes and services addressing the prevention and management of infectious diseases and their complications in PWID could lead to focused interventions to enhance care in this population.

Methods and analysis

An integrative systematic review allows for inclusion of a variety of methodologies to understand a health issue from different viewpoints. PubMed, CINAHL, Web of Science Databases and websites of the Public Health Agency of Canada, Canadian Institute for Substance Use Research, and Canadian Centre on Substance Use and Addiction will be searched using terms for infectious diseases, drug use and geography (Canada) and limited to the last 10 years (2009–2019). The Quality Appraisal Tool in Studies with Diverse Designs will be used to appraise the quality of identified studies and documents. Quantitative, qualitative or mixed methods data synthesis will be used as needed.

Ethics and dissemination

This study is a secondary analysis of publicly available documents; therefore, no ethics approval is required. This information will inform a research agenda to further investigate interventions that aim to address these issues.

PROSPERO registration number

CRD42020142947.
Impact of incremental versus conventional initiation of haemodialysis on residual kidney function: study protocol for a multicentre feasibility randomised controlled trial
Authors: Kaja Kamal Raja Mohammed , Farrington Ken , Wellsted David , Sridharan Sivakumar , Alchi Bassam , Burton James , Davenport Andrew , Vilar Enric
Published: August 2020

Introduction

Preserving residual kidney function (RKF) may be beneficial to patients on haemodialysis (HD) and it has been proposed that commencing dialysis incrementally rather than three times a week may preserve RKF. In Incremental HD, target dose includes a contribution from RKF, which is added to HD dose, allowing individualisation of the HD prescription. We will conduct a feasibility randomised controlled trial (RCT) comparing incremental HD and conventional three times weekly treatments in incident HD patients. The study is designed also to provide pilot data to allow determination of effect size to power a definitive study.

Methods and analysis

After screening to ensure native renal urea clearance >3 mL/min/1.73 m2, the study will randomise 54 patients within 3 months of HD initiation to conventional in-centre thrice weekly dialysis or incremental in-centre HD commencing 2 days a week. Subjects will be followed up for 12 months. The study will be carried out across four UK renal centres.

The primary outcome is to evaluate the feasibility of conducting a definitive RCT and to estimate the difference in rate of decline of RKF between the two groups at 6 and 12 months time points. Secondary outcomes will include the impact of dialysis intensity on vascular access events, major adverse cardiac events and survival. Impact of dialysis intensity on patient-reported outcomes measures, cognition and frailty will be assessed using EQ-5D-5L, PHQ-9, Illness Intrusiveness Rating Score, Montreal Cognitive assessment and Clinical Frailty Score. Safety outcomes include hospitalisation, fluid overload episodes, hyperkalaemia events and vascular access events.

This study will inform the design of a definitive study, adequately powered to determine whether RKF is better preserved after incremental HD initiation compared with conventional initiation.

Ethics and dissemination

Ethics approval has been granted by Cambridge South Research Ethics Committee, United Kingdom(REC17/EE/0311). Results will be disseminated via peer-reviewed publication.

Trial registration number

NCT03418181
How do aggression source, employee characteristics and organisational response impact the relationship between workplace aggression and work and health outcomes in healthcare employees? A cross-sectional analysis of the National Health Service staff survey in England
Authors: Cheng Shannon , Dawson Jeremy , Thamby Julie , Liaw Winston R , King Eden B
Published: August 2020

Objectives

To examine the prevalence of aggression in healthcare and its association with employees’ turnover intentions, health and engagement, as well as how these effects differ based on aggression source (patients vs colleagues), employee characteristics (race, gender and occupation) and organisational response to the aggression.

Design

Multilevel moderated regression analysis of 2010 National Health Service (NHS) survey.

Setting

147 acute NHS trusts in England.

Participants

36 850 participants across three occupational groups (14% medical/dental, 61% nursing/midwifery, 25% allied health professionals or scientific and technical staff).

Main outcome measures

Employee turnover intentions, health and work engagement.

Results

Both forms of aggression (from patients and colleagues) have significant and substantial effects on turnover intentions, health and work engagement; however, for all three outcome variables, the effect of aggression from colleagues is more than twice the size of the effect of aggression from patients. Organisational response was found to buffer the negative effects of aggression from patients for turnover intentions and the negative effects of aggression from patients and colleagues for employee health. The results also demonstrated that nurses/midwives, women and Black employees are more likely to experience aggression; however, no clear patterns emerged on how aggression differentially impacts employees of different races, genders and occupations with respect to the outcome variables.

Conclusions

Although aggression from patients and colleagues both have negative effects on healthcare employees’ turnover intentions, health and work engagement, these negative effects are worse when it is aggression from colleagues. Having an effective organisational response can help ameliorate the negative effects of aggression on employees’ health; however, it may not always buffer negative effects on turnover intentions and work engagement. Future research should examine other approaches, as well as how organisational responses and resources may need to differ based on aggression source.