bluuebunny/crossref_metadata_2025 huggingface dataset:
Using a reaction‐diffusion model to estimate day respiration and reassimilation of (photo)respired CO2 in leaves
Authors: Berghuijs Herman N. C. , Yin Xinyou , Ho Q. Tri , Retta Moges A. , Nicolaï Bart M. , Struik Paul C.
Published: April 2019

Methods using gas exchange measurements to estimate respiration in the light (day respiration ) make implicit assumptions about reassimilation of (photo)respired CO2; however, this reassimilation depends on the positions of mitochondria.

We used a reaction‐diffusion model without making these assumptions to analyse datasets on gas exchange, chlorophyll fluorescence and anatomy for tomato leaves. We investigated how values obtained by the Kok and the Yin methods are affected by these assumptions and how those by the Laisk method are affected by the positions of mitochondria.

The Kok method always underestimated . Estimates of by the Yin method and by the reaction‐diffusion model agreed only for nonphotorespiratory conditions. Both the Yin and Kok methods ignore reassimilation of (photo)respired CO2, and thus underestimated for photorespiratory conditions, but this was less so in the Yin than in the Kok method. Estimates by the Laisk method were affected by assumed positions of mitochondria. It did not work if mitochondria were in the cytosol between the plasmamembrane and the chloroplast envelope. However, mitochondria were found to be most likely between the tonoplast and chloroplasts.

Our reaction‐diffusion model effectively estimates , enlightens the dependence of estimates on reassimilation and clarifies (dis)advantages of existing methods.
Meta‐analysis of the role of entomopathogenic and unspecialized fungal endophytes as plant bodyguards
Authors: Gange Alan C. , Koricheva Julia , Currie Amanda F. , Jaber Lara R. , Vidal Stefan
Published: April 2019

Herbaceous plants harbour species‐rich communities of asymptomatic endophytic fungi. Although some of these endophytes are entomopathogenic, many are not, and remarkably little is known about how the presence of these fungi in plant tissues affects phytophagous insects.

Here we show through a meta‐analysis that both entomopathogenic and nonentomopathogenic endophytes have a negative effect on insect herbivores. Growth and performance of polyphagous and sucking insects are reduced by nonentomopathogenic endophytes, but monophages are unaffected, likely because the latter are better adapted to secondary metabolites produced or induced by the fungi.

Furthermore, studies using excised leaves report weaker effects than those with intact plants, likely caused by chemical changes being masked by leaf excision. Most surprisingly, endophyte infection of seeds produces the greatest effect on insect herbivores in subsequent mature plants, even though the usual mode of fungal transmission is infection of leaves by airborne spores.

We conclude that these ubiquitous hidden fungi may be important bodyguards of plants. However, in order to fully understand their roles in plant protection, we must be aware that minor differences in experimental design can lead to contradictory results.
The effect of pediatric patient temperament on postoperative outcomes
Authors: Uhl Kristen , Litvinova Anna , Sriswasdi Patcharee , Zurakowski David , Logan Deirdre , Cravero Joseph P.
Published: April 2019

Background

Research has improved practitioner awareness of the impact of individual characteristics on responses to painful procedures. However, there is little data relating preexisting temperament profiles and postsurgical/anesthesia outcomes in pediatric patients. In particular, it is not clear how best to identify which patients are at risk of poor postsurgical outcomes.

Aim

In this prospective study, we examined relationships between preoperative measures of child temperament and postoperative pain/behavioral outcomes of children undergoing tonsillectomy/adenoidectomy surgeries. We sought to determine which temperament profiles were predictive of poor outcomes.

Methods

After IRB approval and informed consent, validated temperament surveys were administered to the parents of a cohort of children undergoing tonsillectomy/adenoidectomy surgery. These data were combined with preoperative, intraoperative, and postoperative outcome measures collected from the electronic medical record utilizing a large integrated anesthesia outcome database. The dataset was further augmented with surveys addressing remote postoperative behaviors. Analysis of the temperament data yielded four groups (positive, negative, excitable, and inhibitory). The probability of high perioperative pain, agitation, emesis, and postoperative behavior changes based on cluster membership was then assessed.

Results

A total of 260 patients undergoing tonsillectomy and/or adenoidectomy surgeries were enrolled in the study. ANOVA and chi‐squared analyses indicated no statistically significant age, gender, or anesthesia technique differences across the four temperament clusters. Temperament cluster membership was not related to emesis, agitation, or behavioral changes. However, it was found to be predictive of high postoperative pain. Members of the excitable cluster (high positive and negative emotionality) were more likely to report high pain than those in positive cluster (high positive, low negative emotionality) (OR 7.97, 95% CI: 1.62‐39.26; P < 0.05). Comparisons among other clusters were not significant.

Conclusion

Our data indicate that preoperative temperament characteristics may differentially influence pediatric postoperative pain experience in children. Specifically, children with high levels of positive and negative emotionality may exhibit more postsurgical pain behaviors.
CRISPR/Cas9‐mediated functional recovery of the recessive rc allele to develop red rice
Authors: Zhu Yiwang , Lin Yarong , Chen Songbiao , Liu Huaqing , Chen Zaijie , Fan Meiying , Hu Taijiao , Mei Fating , Chen Jianmin , Chen Liang , Wang Feng
Published: April 2019

Red rice contains high levels of proanthocyanidins and anthocyanins, which have been recognized as health‐promoting nutrients. The red coloration of rice grains is controlled by two complementary genes, Rc and Rd. The RcRd genotype produces red pericarp in wild species Oryza rufipogon, whereas most cultivated rice varieties produce white grains resulted from a 14‐bp frame‐shift deletion in the seventh exon of the Rc gene. In the present study, we developed a CRISPR/Cas9‐mediated method to functionally restore the recessive rc allele through reverting the 14‐bp frame‐shift deletion to in‐frame mutations in which the deletions were in multiples of three bases, and successfully converted three elite white pericarp rice varieties into red ones. Rice seeds from T1 in‐frame Rc lines were measured for proanthocyanidins and anthocyanidins, and high accumulation levels of proanthocyanidins and anthocyanidins were observed in red grains from the mutants. Moreover, there was no significant difference between wild‐type and in‐frame Rc mutants in major agronomic traits, indicating that restoration of Rc function had no negative effect on important agronomic traits in rice. Given that most white pericarp rice varieties are resulted from the 14‐bp deletion in Rc, it is conceivable that our method could be applied to most white pericarp rice varieties and would greatly accelerate the breeding of new red rice varieties with elite agronomic traits. In addition, our study demonstrates an effective approach to restore recessive frame‐shift alleles for crop improvement.
A gamma‐thionin protein from apple, MdD1, is required for defence against S‐RNase‐induced inhibition of pollen tube prior to self/non‐self recognition
Authors: Gu Zhaoyu , Li Wei , Doughty James , Meng Dong , Yang Qing , Yuan Hui , Li Yang , Chen Qiuju , Yu Jie , Liu Chun sheng , Li Tianzhong
Published: April 2019

Apple exhibits S‐RNase‐mediated self‐incompatibility. Although the cytotoxic effect of S‐RNase inside the self‐pollen tube has been studied extensively, the underlying defence mechanism in pollen tube in Rosaceae remains unclear. On exposure to stylar S‐RNase, plant defence responses are activated in the pollen tube; however, how these are regulated is currently poorly understood. Here, we show that entry of both self and non‐self S‐RNase into pollen tubes of apple (Malus domestica) stimulates jasmonic acid (JA) production, in turn inducing the accumulation of MdMYC2 transcripts, a transcription factor in the JA signalling pathway widely considered to be involved in plant defence processes. MdMYC2 acts as a positive regulator in the pollen tube activating expression of MdD1, a gene encoding a defence protein. Importantly, MdD1 was shown to bind to the RNase activity sites of S‐RNase leading to inhibition of enzymatic activity. This work provides intriguing insights into an ancient defence mechanism present in apple pollen tubes where MdD1 likely acts as a primary line of defence to inhibit S‐RNase cytotoxicity prior to self/non‐self recognition.
Nitrogen utilisation and metabolism in maize (Zea mays L.) plants under different rates of biochar addition and nitrogen input conditions
Authors: Sun C.X. , Hao L. , Wang D. , Li C. , Zhang C. , Chen X. , Fu J. , Zhang Y.L.
Published: April 2019

Biochar (BC) application could improve plant nitrogen (N) utilisation and potentially reduce N fertiliser requirements. However, the fate of N in crop–soil systems and the metabolic responses of crops under conditions of BC co‐applied with reduced N are not well understood.

The urea‐15N isotope and pot experiments with three BC rates (0%, 5% and 15%; w/w) combined with three N fertiliser levels (100% N, 85% N and 55% N) were conducted for maize. The metabolome, 15N abundance and gene expression in plants were analysed using nuclear magnetic resonance, gas isotope mass spectrometry and quantitative real‐time reverse transcription PCR, respectively.

The results showed that recovery of N by maize ranged from 27.4% to 23.6% and decreased as the N application rate decreased (from 100% to 55%) without BC addition, but ranged from 24.6% to 29.4% when BC was added at a rate of 5% and increased as the N application rate decreased. BC addition had major effects on global metabolic profiles and metabolic networks at the metabolomics level as well as on the expression of related genes (zmGS1and zmAS1) and the content of mineral N (NO3−, NO2− and NH4+) in maize seedlings; moreover, the interaction effects of the BC application rates and N fertiliser levels were evident (P ≤ 0.001).

BC addition induced a decrease in the flux toward sugar hydrolysis and maintained homeostasis in the amino acid pool, which was perturbed by reduced N levels; after which the maize plants adapted to the reduced N condition, and the N recovery efficiency ultimately improved with reduced N loss.
The comparison of reproductive hormone receptor expressions of the sheep ovary and hormone concentrations in two Chinese breeds
Authors: Li Liangyuan , Lu Shouliang , Ma Qiman , Wan Pengcheng , Liu Changbin , Yang Hanyulu , Yang Hua , Yang Yonglin , Dai Rong , Shi Guoqing
Published: April 2019

The aim of this research was to investigate the changes in reproductive hormone receptor expressions of the ovary and hormone concentrations between oestrous cycle pattern of two different sheep breeds in China. Ovarian tissues were collected from Chinese Merino (Junken type) and Hu sheep with different reproductive states in spring and autumn. Serum samples were assayed for oestrogen (E2), progesterone (P), luteinizing hormone (LH) and follicle‐stimulating hormone (FSH) concentrations by radioimmunoassay during spring. The ovarian expression of hormone receptors (ERα, ERβ, PR, LHR and FSHR) was analysed using real‐time reverse transcription polymerase chain reaction (RT‐PCR). In Chinese Merino, there was no corpora lutea and ovulation point on the surfaces of ovaries in spring and low basal levels of both LH and P in serum. ERα, ERβ and FSHR were expressed significantly higher in Merino ovaries during anoestrus compared with oestrous or luteal phases of Hu sheep (p < 0.05 or p < 0.01). However, both varieties of sheep exhibited a similar tendency to secrete E2 and FSH. Compared with Hu sheep, FSH levels were slightly higher in Merino serum. In Hu sheep, ERα, ERβ, FSHR, LHR and PR expressed in luteal phase ovaries during spring were significantly lower (p < 0.05, p < 0.01 or p < 0.001) than autumn. Interestingly, LHR and PR expressed in anoestrous ovaries were similar to that in oestrous phase of both sheep breeds. The above results suggest that seasonal reproductive sheep increased the expression of E2 and FSH receptors in ovary during spring may enhance the effects of E2 and FSH on follicular development. It is likely that this enhancement prevents the ovary from progressing to the luteal phase.
Confidence in Risk Assessments
Authors: Rougier Jonathan
Published: April 2019

Risk is assessed with varying degrees of confidence, and the degree of confidence is relevant to the risk manager. The paper proposes an operational framework for representing confidence, based on an expert's current beliefs about how her beliefs might be different in the future. Two modelling simplifications, ‘no unknown unknowns’ and a homogeneous Poisson process, make this framework trivial to apply. This is illustrated for assessing an exceedance probability for a large event, with volcanic risk as a specific example. The paper ends with a discussion about risk and confidence assessments for national scale risk assessment, including several further illustrations.
Heterogeneous macrophages: Supersensors of exogenous inducing factors
Authors: Qian Caiyun , Yun Zehui , Yao Yudi , Cao Minghua , Liu Qiang , Hu Song , Zhang Shuhua , Luo Daya
Published: April 2019

As heterogeneous immune cells, macrophages mount effective responses to various internal and external changes during disease progression. Macrophage polarization, rather than macrophage heterogenization, is often used to describe the functional differences between macrophages. While macrophage polarization partially contributes to heterogeneity, it does not completely explain the concept of macrophage heterogeneity. At the same time, there are abundant and sophisticated endogenous and exogenous substances that can affect macrophage heterogeneity. While the research on endogenous factors has been systematically reviewed, the findings on exogenous factors have not been well summarized. Hence, we reviewed the characteristics and inducing factors of heterogeneous macrophages to reveal their functional plasticity as well as their targeting manoeuvreability. In the process of constructing and analysing a network organized by disease‐related cells and molecules, paying more attention to heterogeneous macrophages as mediators of this network may help to explore a novel entry point for early prevention of and intervention in disease.
Questions of Order in the U.S. Senate: Procedural Uncertainty and the Role of the Parliamentarian*
Authors: Madonna Anthony J. , Lynch Michael S. , Williamson Ryan D.
Published: April 2019

Objectives

Scholarship on the U.S. Senate has demonstrated the pivotal role the presiding officer can play when asked to interpret the chamber's rules and precedents. Therefore, our objective is to broadly evaluate how questions of order are arbitrated in the U.S. Senate.

Methods

Using a multinomial logistic regression, we estimate the effect of partisanship on adjudicating questions of order in the Senate before and after the institutionalization of the parliamentarian.

Results

Our results indicate that while short‐term partisan interests play an important role in determining how presiding officers interpret rules and precedents, the emergence of the Senate parliamentarian in the 1920s served to reduce uncertainty regarding procedural matters in the chamber.

Conclusions

This change has led to fewer instances of partisan rulings on questions of order and raised the costs of executing a drastic change in Senate procedure via unorthodox procedures. However, the introduction of the parliamentarian has not reduced the likelihood a ruling is overturned. As such, more narrow procedural changes have been used to support majorities over time.
Endotipsitis as an indication for pediatric liver transplantation
Authors: Juamperez Javier , Quintero Jesús , Muntaner Antoni , Pérez Mercedes , Len Oscar , Charco Ramón
Published: April 2019

Endotipsitis is a rare but severe complication of transjugular intrahepatic portosystemic shunt (TIPS), a device widely used to treat portal hypertension in adults, but sparsely used in children. We report a case of endotipsitis in a 3‐year‐old child affected of biliary atresia. She underwent a Kasai procedure at 3 months of age but, although the bile flow was restored, she presented upper gastrointestinal bleeding due to portal hypertension 1.5 years later. A TIPS was placed in order to control the hemorrhage. A year after TIPS placement, she started presenting repeated episodes of cholangitis. Blood cultures were positive to Enterobacter cloacae. Even with long antibiotic courses, adjusted to blood cultures, infectious signs were observed after antibiotic withdrawal. Device infection was demonstrated through Positron emission tomography‐Computed tomography scan. The patient was listed for liver transplantation, and intravenous antibiotic treatment was maintained until stent removal during the liver transplant 8 months later. No infectious complications were demonstrated after the surgery. To the best of our knowledge, this is the first case report of endotipsitis described in a pediatric patient.
Diagnostic accuracy of non‐specialist versus specialist health workers in diagnosing hearing loss and ear disease in Malawi
Authors: Bright Tess , Mulwafu Wakisa , Phiri Mwanaisha , Ensink Robbert J. H. , Smith Andrew , Yip Jennifer , Mactaggart Islay , Polack Sarah
Published: April 2019

Objective

To determine whether a non‐specialist health worker can accurately undertake audiometry and otoscopy, the essential clinical examinations in a survey of hearing loss, instead of a highly skilled specialist (i.e. ENT or audiologist).

Methods

A clinic‐based diagnostic accuracy study was conducted in Malawi. Consecutively sampled participants ≥ 18 years had their hearing tested using a validated tablet‐based audiometer (hearTest) by an audiologist (gold standard), an audiology officer, a nurse and a community health worker (CHW). Otoscopy for diagnosis of ear pathologies was conducted by an ENT specialist (gold standard), an ENT clinical officer, a CHW, an ENT nurse and a general nurse. Sensitivity, specificity and kappa (κ) were calculated. 80% sensitivity, 70% specificity and kappa of 0.6 were considered adequate.

Results

Six hundred and seventeen participants were included. High sensitivity (>90%) and specificity (>85%) in detecting bilateral hearing loss was obtained by all non‐specialists. For otoscopy, sensitivity and specificity were >80% for all non‐specialists in diagnosing any pathology except for the ENT nurse. Agreement in diagnoses for the ENT clinical officer was good (κ = 0.7) in both ears. For other assessors, moderate agreement was found (κ = 0.5).

Conclusion

A non‐specialist can be trained to accurately assess hearing using mobile‐based audiometry. However, accurate diagnosis of ear conditions requires at least an ENT clinical officer (or equivalent). Conducting surveys of hearing loss with non‐specialists could lower costs and increase data collection, particularly in low‐ and middle‐income countries, where ENT specialists are scarce.
Membrane lipid polyunsaturation mediated by FATTY ACID DESATURASE 2 (FAD2) is involved in endoplasmic reticulum stress tolerance in Arabidopsis thaliana
Authors: Nguyen Van Cam , Nakamura Yuki , Kanehara Kazue
Published: April 2019

Unsaturation of membrane glycerolipid classes at their hydrophobic fatty acid tails critically affects the physical nature of the lipid molecule. In Arabidopsis thaliana, 7 fatty acid desaturases (FADs) differently desaturate each glycerolipid class in plastids and the endoplasmic reticulum (ER). Here, we showed that polyunsaturation of ER glycerolipids is required for the ER stress response. Through systematic screening of FAD mutants, we found that a mutant of FAD2 resulted in a hypersensitive response to tunicamycin, a chemical inducer of ER stress. FAD2 converts oleic acid to linoleic acid of the fatty acyl groups of ER‐synthesized phospholipids. Our functional in vivo reporter assay revealed the ER localization and distinct tissue‐specific expression patterns of FAD2. Moreover, glycerolipid profiling of both mutants and overexpressors of FAD2 under tunicamycin‐induced ER stress conditions, along with phenotypic screening of the mutants of the FAD family, suggested that the ratio of monounsaturated fatty acids to polyunsaturated fatty acids, particularly 18:1 to 18:2 species, may be an important factor in allowing the ER membrane to cope with ER stress. Therefore, our results suggest that membrane lipid polyunsaturation mediated by FAD2 is involved in ER stress tolerance in Arabidopsis.
Cystathionine beta‐lyase is crucial for embryo patterning and the maintenance of root stem cell niche in Arabidopsis
Authors: Liu Guolan , Yang Weiyuan , Zhang Xiaojing , Peng Tao , Zou Yi , Zhang Tao , Wang Hao , Liu Xuncheng , Tao Li‐Zhen
Published: April 2019

The growth and development of roots in plants depends on the specification and maintenance of the root apical meristem. Here, we report the identification of CBL, a gene required for embryo and root development in Arabidopsis, and encodes cystathionine beta‐lyase (CBL), which catalyzes the penultimate step in methionine (Met) biosynthesis, and which also led to the discovery of a previous unknown, but crucial, metabolic contribution by the Met biosynthesis pathway. CBL is expressed in embryos and shows quiescent center (QC)‐enriched expression pattern in the root. cbl mutant has impaired embryo patterning, defective root stem cell niche, stunted root growth, and reduces accumulation of the root master regulators PLETHORA1 (PLT1) and PLT2. Furthermore, mutation in CBL severely decreases abundance of several PIN‐FORMED (PIN) proteins and impairs auxin‐responsive gene expression in the root tip. cbl seedlings also exhibit global reduction in histone H3 Lys‐4 trimethylation (H3K4me3) and DNA methylation. Importantly, mutation in CBL reduces the abundance of H3K4me3 modification in PLT1/2 genes and downregulates their expression. Overexpression of PLT2 partially rescues cbl root meristem defect, suggesting that CBL acts in part through PLT1/2. Moreover, exogenous supplementation of Met also restores the impaired QC activity and the root growth defects of cbl. Taken together, our results highlight the unique role of CBL to maintain the root stem cell niche by cooperative actions between Met biosynthesis and epigenetic modification of key developmental regulators.
Void
Growth and Coalescence in Porous Plastic Solids With Sigmoidal
Hardening
Authors: Indurkar Padmeya
P. , Joshi Shailendra
P.
Published: April 2019

This paper presents an analysis of void growth and coalescence in isotropic, elastoplastic materials exhibiting sigmoidal hardening using unit cell calculations and micromechanics-based damage modeling. Axisymmetric finite element unit cell calculations are carried out under tensile loading with constant nominal stress triaxiality conditions. These calculations reveal the characteristic role of material hardening in the evolution of the effective response of the porous solid. The local heterogeneous flow hardening around the void plays an important role, which manifests in the stress–strain response, porosity evolution, void aspect ratio evolution, and the coalescence characteristics that are qualitatively different from those of a conventional power-law hardening porous solid. A homogenization-based damage model based on the micromechanics of void growth and coalescence is presented with two simple, heuristic modifications that account for this effect. The model is calibrated to a small number of unit cell results with initially spherical voids, and its efficacy is demonstrated for a range of porosity fractions, hardening characteristics, and void aspect ratios.
Experimental Analysis of Natural Convection and Flow Visualization in an Asymmetrically Heated Open Vertical Channel
Authors: Cherif Yassine , Sassine Emilio , Zalewski Laurent , Souidi Kaies , Lassue Stephane
Published: April 2019

An experimental device was designed to perform the thermal and dynamic study of natural convection airflow in an open vertical channel. The two side walls of the vertical channel are made of Plexiglas allowing the visualization of the flow via the particle image velocimetry (PIV) method. For the two other vertical walls, one is heated at a constant temperature, and the other is insulated with a 9-cm thick polystyrene insulation. The dynamic characterization of convection is carried out by nonintrusive measurements (PIV), and thermal phenomena are analyzed using nonintrusive heat flux instrumentation (simultaneous temperature and velocity measurements have been carried out across the channel at different elevations). Moreover, this study deals with the influence of the Rayleigh number on the measured vertical velocity profiles as well as the thermal flux densities recorded along the heated wall. To do this, different values of the modified Rayleigh numbers were considered in the interval with the channel aspect ratio of A = 5 and A = 12.5. The obtained Nusselt number values have been compared successfully with those of the literature. The impacts of the Rayleigh number and the aspect ratio on the velocity profiles and the convective and radiative heat transfer have been examined.
Discussion of “Magnetohydrodynamic Mixed Convective Flow Due to a Vertical Plate With Induced Magnetic Field” (Nandkeolyar, R., Narayana, M., Motsa, S. S., and Sibanda, P., 2018, ASME J. Therm. Sci. Eng. Appl., 10(6), p. 061005)
Authors: Pantokratoras Asterios
Published: April 2019

The present discussion queries some results included in the above paper.
Conversion System for Grid-to-Vehicle and Vehicle-to-Grid Applications
Authors: Marinho Diogo , Chaves Miguel , Gambôa Paulo , Lopes José
Published: April 2019

The increasing use of electrical vehicles aroused the problem of batteries charging and the consequent interface with the power grid. Commercial charging solutions are mostly based on unidirectional power flow converters; however, bidirectional power flow converters are an interesting solution when considering smart microgrid applications, with benefits in efficient energy use. In this context, the paper presents a bidirectional power flow converter for grid-to-vehicle (G2V) or vehicle-to-grid (V2G) applications. The conversion system is based on a three-phase voltage source inverter (VSI), which assures the grid connection with a unitary power factor. The direct current (DC) bus of the voltage source inverter is connected to a DC/DC converter that controls the battery power flow. This conversion system can operate in G2V mode when charging the battery or in V2G mode when working as an energy storage system and the power flow is from the battery to the power grid. The conversion system model is presented as well as the control strategy proposed. Simulation and experimental results showing voltages and currents in the circuit are also presented.
Influence of Sea Current on Stabilization of Moments and Forces in Risers
Authors: Adamiec-Wójcik Iwona , Brzozowska Lucyna , Wojciech Stanisław
Published: April 2019

One of the important aspects in the design of floating, production, storage, and offloading (FPSO) systems is to ensure a fairly constant load on risers despite the base motion caused by sea waves. The paper presents the authors’ own formulation of the finite segment method for dynamic analysis of risers and its application to the solution of a dynamic optimization problem. This task consists in defining vertical displacements of the top of the riser which compensate horizontal movements of the vessel or platform caused by sea waves. Compensation involves stabilizing the bending moment in the risers or the force in the connection of the riser and the wellhead. The model takes into account the influence of the sea by means of Morison equations. Different sea current profiles are considered. Calculation of vertical displacements of the top of the riser is carried out in order to stabilize the force or the bending moment for a defined function of horizontal displacements of the riser.
Investigation
on Nonlinear Dynamic Characteristics of a New Rigid-Flexible Gear Transmission With
Wear
Authors: Geng Zhibo , Xiao Ke , Wang Jiaxu , Li Junyang
Published: April 2019

At present, the mean value of the meshing stiffness and the gear backlash is a fixed value in the nonlinear dynamic model. In this study, wear is considered in the model of the gear backlash and time-varying stiffness. With the increase of the operating time, the meshing stiffness decreases and the gear backlash increases. A six degrees-of-freedom nonlinear dynamic model of a new rigid-flexible gear pair is established with time-varying stiffness and time-varying gear backlash. The dynamic behaviors of the gear transmission system are studied through bifurcation diagrams with the operating time as control parameters. Then, the dynamic characteristics of the gear transmission system are analyzed using excitation frequency as control parameters at four operating time points. The bifurcation diagrams, Poincaré maps, fast Fourier transform (FFT) spectra, phase diagrams, and time series are used to investigate the state of motion. The results can provide a reference for the gear transmission system with wear.
How bright was the Big Bang?
Authors: Andersen Christopher , Rosenstroem Charlotte Amalie , Ruchayskiy Oleg
Published: April 2019

It is generally believed that in the epoch prior to the formation of the first stars, the Universe was completely dark (the period is therefore known as the Dark Ages). Usually, the start of this epoch is placed at photon decoupling. In this work, we investigate the question whether there was enough light during the dark epoch for a human eye to see. We use the black body spectrum of the Universe to find the flux of photon energy for different temperatures and compare them with visual limits of brightness and darkness. We find that the Dark Ages actually began approximately 6 × 106 years later than commonly stated.
Resource Letter RBAI-2: Research-based assessment instruments: Beyond physics topics
Authors: Madsen Adrian , McKagan Sarah B. , Sayre Eleanor C. , Paul Cassandra A.
Published: April 2019

This Resource Letter provides a guide to research-based assessment instruments (RBAIs) that can be used in physics classes to assess attitudes and beliefs about physics, epistemologies and expectations, the nature of physics, problem solving, self-efficacy, reasoning skills, and lab skills. We also discuss RBAIs in physics cognate fields, such as mathematics, and observation protocols for standardized observation of teaching. In this Resource Letter, we present an overview of these assessments and surveys including research validation, instructional level, format, and themes, to help faculty find the assessment that most closely matches their goals. This Resource Letter is a companion to “RBAI-1: Research-based Assessment Instruments in Physics and Astronomy,” which explicitly dealt with physics and astronomy topics. More details about each RBAI discussed in this paper are available at PhysPort: www.physport.org/assessments.
New video resource for calculus-based introductory physics, design and assessment. I. Electricity and magnetism
Authors: Perry Jonathan D. , Erukhimova Tatiana L. , Bassichis William H.
Published: April 2019

A new online video resource named Freshman Physics Classroom (FPC) was developed by a team in the Department of Physics & Astronomy at Texas A&M University to supplement calculus-based introductory physics courses. This article describes the development of this resource and reports the results from the first term of deployment, spring 2017, for student performance on both course examinations and the Brief Electricity & Magnetism Assessment (BEMA). The video modules received a high approval rating (>85%) from students according to anonymous clicker surveys administered twice over the course of the semester during lectures. Data from midterm exams show that students who engaged with the resource tended to outperform students who did not make use of the FPC video modules. Distributions of exam scores indicate that students with partial understanding of a subject from the course (lectures, recitations, and so forth) benefited from engagement with the video modules. Students from the spring semesters of 2015–2017 showed nearly identical levels of conceptual knowledge according to pre-testing conducted using BEMA, where spring 2015 and spring 2016 were used as a control group. Normalized gains were higher on average for those students who made use of the FPC video modules than for those who did not. Overall, the FPC video modules demonstrated a positive influence on student conceptual understanding and problem solving ability.
Polarization in electrostatics and circuits: Computing and visualizing surface charge distributions
Authors: Chabay Ruth , Sherwood Bruce
Published: April 2019

In electrostatic situations and in steady-state circuits, charges on the surface of a conductor contribute significantly to the net electric field inside the conductor. These charges build up quickly due to transient currents that are initiated by the presence of external charged objects or objects such as batteries that maintain a charge separation. We describe an algorithm for computing the detailed surface charge distributions in equilibrium electrostatic situations and in steady-state DC circuits, and discuss the results of our computations of surface charge distributions for several systems. The results show that in simple DC circuit geometries a roughly constant gradient of surface charge plays a dominant role in establishing the net field inside circuit elements. Three-dimensional visualization contributes to new insights into surface charge distributions on circuit elements.
Characterization of inter-speaker articulatory variability: A two-level multi-speaker modelling approach based on MRI data
Authors: Serrurier Antoine , Badin Pierre , Lamalle Laurent , Neuschaefer-Rube Christiane
Published: April 2019

Speech communication relies on articulatory and acoustic codes shared between speakers and listeners despite inter-individual differences in morphology and idiosyncratic articulatory strategies. This study addresses the long-standing problem of characterizing and modelling speaker-independent articulatory strategies and inter-speaker articulatory variability. It explores a multi-speaker modelling approach based on two levels: statistically-based linear articulatory models, which capture the speaker-specific articulatory variability on the one hand, are in turn controlled by a speaker model, which captures the inter-speaker variability on the other hand. A low dimensionality speaker model is obtained by taking advantage of the inter-speaker correlations between morphology and strategy. To validate this approach, contours of the vocal tract articulators were manually segmented on midsagittal MRI data recorded from 11 French speakers uttering 62 vowels and consonants. Using these contours, multi-speaker models with 14 articulatory components and two morphology and strategy components led to overall variance explanations of 66%–69% and root-mean-square errors of 0.36–0.38 cm obtained in leave-one-out procedure over the speakers. Results suggest that inter-speaker variability is more related to the morphology than to the idiosyncratic strategies and illustrate the adaptation of the articulatory components to the morphology.
Detailed analysis of two detected overlaying transient components within the echolocation beam of a bottlenose dolphin (Tursiops truncatus)
Authors: Starkhammar Josefin , Reinhold Isabella , Moore Patrick W. , Houser Dorian S. , Sandsten Maria
Published: April 2019

Dolphin echolocation clicks measured far off-axis contain two time-separated components. Whether these components overlap and appear as a single signal on axis has received little attention. Here, the scaled reassigned spectrogram analysis was used to examine if bottlenose dolphin (Tursiops truncatus) clicks measured near- or on-axis of the echolocation beam contained overlapping components. Across click trains, the number of overlapping components spatially varied within the echolocation beam. Two overlapping components were found to predominantly occur in the upper portion of the beam, whereas the lower portion of the beam predominantly contained a single component. When components overlapped, the trailing component generally had a higher center frequency and arrived less than 5 μs after the leading component. The spatial relationship of components was consistent with previous findings of two vertically distinct beam lobes with separated frequency content. The two components in the upper portion of the beam possibly result from a single transient click propagating through a geometrically dispersive media; specifically, the slower sound speed of the dolphin melon's core slightly delays the more directional, high frequency energy of the click, whereas the less directional, lower frequency energy propagates through more peripheral but higher sound speed portions of the melon.
Ultrasonic wave propagation predictions for polycrystalline materials using three-dimensional synthetic microstructures: Attenuation
Authors: Norouzian Musa , Turner Joseph A.
Published: April 2019

Ultrasonic attenuation plays a crucial role in inspection for heterogeneous materials such that theoretical models are critical for improved measurements. In this article, several assumptions often used in these models are examined with respect to their influence on attenuation. Here, dream.3d software is used to generate 10 ensembles with different volumes, each containing 50 realizations of equiaxed grains with cubic single-crystal symmetry, from which attenuations are calculated. Comparisons are then made with attenuation values derived from classical theories. These theories often decouple the spatial and tensorial components of the microstructure, assume statistical isotropy, and use a spatial correlation function that has a specific exponential form. The validity of these assumptions is examined by calculation of the spatial statistics to obtain the attenuations in their most general form. The results of Voigt-averaged results for nickel at 15 MHz show that the longitudinal and transverse attenuations are about one-third and one-fourth of those obtained from the theory, respectively. Such a difference is attributed to the relevant spatial correlation functions. The results also show a slight anisotropy in the attenuation. Finally, for microstructures with narrow grain size distributions and weak texture, the decoupling assumption is shown to be valid.
Energy renormalization for coarse-graining polymers having different segmental structures
Authors: Xia Wenjie , Hansoge Nitin K. , Xu Wen-Sheng , Phelan Frederick R. , Keten Sinan , Douglas Jack F.
Published: April 2019

We provide a computational test of the energy renormalization method to coarse-grain polymers with different segmental structures.
Complex signal processing in synthetic gene circuits using cooperative regulatory assemblies
Authors: Bashor Caleb J. , Patel Nikit , Choubey Sandeep , Beyzavi Ali , Kondev Jané , Collins James J. , Khalil Ahmad S.
Published: April 2019

Cooperativity in synthetic gene circuits

Synthetic biologists would like to be able to make gene regulatory circuits that mimic key properties of eukaryotic gene regulation. Taking a cue from multimeric transcription factor complexes, Bashor
et al.
developed synthetic transcriptional circuits that produce nonlinear behavior from cooperativity (see the Perspective by Ng and El-Samad). Their system uses clamp proteins with multiple protein-interaction domains. Circuit behavior can be tuned by altering the number or affinities of the interactions according to a mathematical model. The authors created synthetic circuits with desired functions common in biology, for example, switch-like behavior or Boolean decision functions.

Science
, this issue p.
593
; see also p.
531
Restriction of PD-1 function by
cis
-PD-L1/CD80 interactions is required for optimal T cell responses
Authors: Sugiura Daisuke , Maruhashi Takumi , Okazaki Il-mi , Shimizu Kenji , Maeda Takeo K. , Takemoto Tatsuya , Okazaki Taku
Published: April 2019

Sparing T cells from inhibition

Programmed cell death 1 (PD-1) is an inhibitory receptor that normally keeps T cell immune responses in check. Immunotherapy targeting PD-1 has proven successful for certain types of cancer, but it remains unclear how PD-1 is regulated. Sugiura
et al.
found that a costimulatory molecule, CD80, can restrict PD-1 function during the activation of T lymphocytes. Binding of CD80 to the PD-1 ligand PD-L1 in cis on primary activated dendritic cells interfered with the ability of PD-L1 to access PD-1 on T cells, which would otherwise have inhibited T cell activation. Functional insights into PD-L1–CD80 interactions may explain the outcomes of anti–PD-1 and anti–PD-L1 cancer therapy.

Science
, this issue p.
558
Carrier lifetimes of >1 μs in Sn-Pb perovskites enable efficient all-perovskite tandem solar cells
Authors: Tong Jinhui , Song Zhaoning , Kim Dong Hoe , Chen Xihan , Chen Cong , Palmstrom Axel F. , Ndione Paul F. , Reese Matthew O. , Dunfield Sean P. , Reid Obadiah G. , Liu Jun , Zhang Fei , Harvey Steven P. , Li Zhen , Christensen Steven T. , Teeter Glenn , Zhao Dewei , Al-Jassim Mowafak M. , van Hest Maikel F. A. M. , Beard Matthew C. , Shaheen Sean E. , Berry Joseph J. , Yan Yanfa , Zhu Kai
Published: April 2019

Efficient all-perovskite tandem cells

Organic-inorganic perovskite films can boost the output of conventional silicon solar cells in tandem geometries by utilizing more of the light at the blue end of the solar spectrum. Tandem cells that use only perovskite films have been less successful because of the lack of a suitable material with a low bandgap that can replace silicon. Tong
et al.
report that a mixed tin-lead organic-inorganic material containing a small fraction of guanidinium thiocyanate has a low bandgap, long charge-carrier lifetime, and efficiencies around 25%.

Science
, this issue p.
475
‘They do not care how much you know until they know how much you care’: a qualitative meta-synthesis of patient experience in the emergency department
Authors: Graham Blair , Endacott Ruth , Smith Jason E , Latour Jos M
Published: April 2019

Background

Patient experience is positively associated with both clinical effectiveness and patient safety and should be a priority for emergency care providers. While both quantitative and qualitative approaches can be used to evaluate patient experience in the emergency department (ED), the latter is well aligned to develop a detailed understanding of features influencing the lived experience of ED patients. This study aimed to systematically review the literature of qualitative studies to identify determinants of adult patient experience in the ED.

Methods

A Preferred Reporting Items for Systematic review and Meta-Analysis compliant systematic review was conducted using PubMed, CINAHL, EMBASE, BNI and bibliography searches to identify qualitative studies exploring patient experiences in ED published in English between 1997 and 2018. Quality assessment was conducted using the Critical Appraisal Skills Programme checklist. Descriptive text and quotations relating to patient experience were extracted from included studies and a meta-synthesis conducted using thematic analysis.

Results

A total of 625 records were screened from which 40 studies underwent full review and 22 were included. Results were coded by two researchers (BG and JML). Meta-synthesis identified 198 discrete units of analysis which were clustered around five analytical themes. These were based on the perceived ‘needs’ of patients visiting the ED and were defined as communication, emotional, competent care, physical/environmental and waiting needs. Findings were translated into a conceptual model for optimising patient experience in the ED.

Conclusion

This meta-synthesis provides a framework for understanding the determinants of patient experience in the ED. The resulting conceptual model and recommendations may have the potential to directly inform practice and improve the patient experience.
We need to talk about Epizelus: ‘PTSD’ and the ancient world
Authors: Rees Owen
Published: April 2019

In the pursuit to offer validity and lineage to the modern diagnosis of post-traumatic stress disorder (PTSD), non-historical scholars often remove ancient episodes from their social context and retrospectively diagnose them based on our modern diagnostic criteria. This approach reinforces our pre-existing ideas, and form a confirmation bias that does not help to grow our understanding of these injuries. As this article argues, the use of ancient precedents would offer greater benefit to the psychological and medical profession when used to ask new questions rather than reiterate old answers. This article addresses the use of ancient history in the psychological disciplines, especially concerning the topic of post-traumatic stress, and its earlier categorisation as shell shock. Before assessing the non-historical scholarship for the use of ancient precedents, this article sets out the historical debate around the topic and the methodological issues involved in using PTSD as a model with which to examine the ancient world. After which, the use of ancient history by psychological and medical researchers examining PTSD will be assessed. In turn, it will be shown how the removal of historical context has allowed misunderstandings of the original texts and for historical errors to permeate. The story of Epizelus, a man who went blind in battle without incurring any injury, will be used as a case study to show how ancient history has been misused, and vital parts of his life story have been ignored because they do not fit the modern diagnostic model. In particular this article will show how ancient episodes have been used to justify modern ideas and modern understanding, and propose new therapies, without the necessary historical due diligence.