bluuebunny/crossref_metadata_2025 huggingface dataset:
Validity and responsiveness of pain rating scales in patients with chronic oral mucosal diseases
Authors: Wiriyakijja Paswach , Porter Stephen , Fedele Stefano , Hodgson Tim , McMillan Roddy , Shephard Martina , Riordain Richeal Ni
Published: March 2021

Objectives

To validate the Visual Analog Scale (VAS) and Numerical Rating Scale (NRS) for measuring pain intensity in chronic oral mucosal diseases.

Methods

Secondary analyses of data including the VAS, NRS, demographic, clinical and quality‐of‐life outcomes at baseline and 4‐month follow‐up were retrieved from a clinical study of chronic oral mucosal diseases. Construct and criterion validity and responsiveness of the VAS and NRS were assessed through testing hypotheses based upon strength of Spearman's correlation coefficients.

Results

Data of 500 and 290 patients with chronic oral mucosal diseases were used for the assessment of validity and responsiveness, respectively. Moderate‐to‐high correlations between both pain scores and scores of clinical and quality‐of‐life outcomes were observed, supporting construct validity of the VAS and NRS. Their criterion validity was confirmed by significantly strong association between scores of both scales. Responsiveness of both scales was adequate based on moderate association between their change scores and global rating of change scale.

Conclusion

The present results provide evidence supporting validity and responsiveness of the VAS and NRS for pain intensity assessment in patients with chronic oral mucosal diseases. Future research examining other pain intensity domains and standardizing composite scores for pain intensity in this population is required.
Picrosirius‐Polarization Method for Collagen Fiber Detection in Tendons: A Mini‐Review
Authors: Liu Jie , Xu Ming‐you , Wu Jing , Zhang Hao , Yang Li , Lun Deng‐xing , Hu Yong‐cheng , Liu Bin
Published: March 2021

Although the structure and composition of collagen have been studied by polarized light microscopy since the early 19th century, many studies and reviews have paid little or no attention to the morphological problems of histopathological diagnosis. The morphology of collagen fibers is critical in guiding mechanical and biological properties in both normal and pathological tendons. Highlighting the organization and spatial distribution of tendon‐containing collagen fibers can be very useful for visualizing a tendon's ultrastructure, biochemical and indirect mechanical properties, which benefits other researchers and clinicians. Picrosirius red (PSR) staining, relying on the birefringence of collagen fibers, is one of the best understood histochemical methods that can highly and specifically underline fibers better than other common staining techniques when combined with polarized light microscopy (PLM). Polarized light microscopy provides complementary information about collagen fibers, such as orientation, type and spatial distribution, which is important for a comprehensive assessment of collagen alteration in a tendon. Here, this brief review serves as a simplistic and important primer to research developments in which differential staining of collagen types by the Picrosirius‐polarization method is increasing in diverse studies of the medical field, mainly in the assessment of the morphology, spatial distribution, and content of collagen in tendons.
CO2 fertilization of Sphagnum peat mosses is modulated by water table level and other environmental factors
Authors: Serk Henrik , Nilsson Mats B. , Figueira João , Wieloch Thomas , Schleucher Jürgen
Published: March 2021

Sphagnum mosses account for most accumulated dead organic matter in peatlands. Therefore, understanding their responses to increasing atmospheric CO2 is needed for estimating peatland C balances under climate change. A key process is photorespiration: a major determinant of net photosynthetic C assimilation that depends on the CO2 to O2 ratio. We used climate chambers to investigate photorespiratory responses of Sphagnum fuscum hummocks to recent increases in atmospheric CO2 (from 280 to 400 ppm) under different water table, temperature, and light intensity levels. We tested the photorespiratory variability using a novel method based on deuterium isotopomers (D6S/D6R ratio) of photosynthetic glucose. The effect of elevated CO2 on photorespiration was highly dependent on water table. At low water table (−20 cm), elevated CO2 suppressed photorespiration relative to C assimilation, thus substantially increasing the net primary production potential. In contrast, a high water table (~0 cm) favored photorespiration and abolished this CO2 effect. The response was further tested for Sphagnum majus lawns at typical water table levels (~0 and −7 cm), revealing no effect of CO2 under those conditions. Our results indicate that hummocks, which typically experience low water table levels, benefit from the 20th century's increase in atmospheric CO2.
SARS‐CoV‐2 and pediatric solid organ transplantation: Current knowns and unknowns
Authors: L’Huillier Arnaud G. , Danziger‐Isakov Lara , Chaudhuri Abanti , Green Michael , Michaels Marian G. , M Posfay‐Barbe Klara , van der Linden Dimitri , Verma Anita , McCulloch Mignon , Ardura Monica I.
Published: March 2021

The COVID‐19 pandemic has proven to be a challenge in regard to the clinical presentation, prevention, diagnosis, and management of SARS‐CoV‐2 infection among children who are candidates for and recipients of SOT. By providing scenarios and frequently asked questions encountered in routine clinical practice, this document provides expert opinion and summarizes the available data regarding the prevention, diagnosis, and management of SARS‐CoV‐2 infection among pediatric SOT candidates and recipients and highlights ongoing knowledge gaps requiring further study. Currently available data are still lacking in the pediatric SOT population, but data have emerged in both the adult SOT and general pediatric population regarding the approach to COVID‐19. The document provides expert opinion regarding prevention, diagnosis, and management of SARS‐CoV‐2 infection among pediatric SOT candidates and recipients.
The Impact of a Spill or Pollution Accident on Firm Environmental Activity: An Empirical Investigation
Authors: Hardcopf Rick , Shah Rachna , Dhanorkar Suvrat
Published: March 2021

Spill and pollution (SP) accidents cause significant damage to the natural environment. They also result in financial costs and reputational losses for the offending firm. As such, understanding how firms respond to such crises is of significant interest to firm stakeholders, such as investors, customers, regulators, NGOs, employees, and local communities. In this study, we examine whether publicly disclosed SP accidents cause firms to alter their approach to environmental management, as expressed by the adoption of environmental management practices (EMPs). Using a unique panel data from 2002 to 2013, representing over 400 publicly traded US manufacturing firms, we find that in the absence of a SP accident, firms adopt more EMPs each year. However, when firms experience a SP accident they respond in surprising ways: while sustainability leading firms do not alter their existing approach to EMP adoption, regardless of the severity of the accident, all other firms do. Firms which are not sustainability leaders escalate the number of EMPs they adopt after low severity accidents and de‐escalate the number of EMPs they adopt after high severity accidents. We also find that de‐escalation can last for up to 3 years and firms do not seem to recover from de‐escalation in future years. Finally, incurring more accidents or more severe accidents leads to greater de‐escalation. Given that the number of EMPs firms adopt determines a firm's environmental performance, de‐escalation can have significant negative consequences for both the natural environment and firms themselves.
Is it Time to Include Post‐Transplant Survival in Heart Transplantation Allocation Rules?
Authors: Hasankhani Farhad , Khademi Amin
Published: March 2021

Identifying an efficient and fair allocation of limited donated hearts to patients on the waiting list is one of the top priorities in heart transplantation management. The recent heart allocation rule by the United Network for Organ Sharing (UNOS) has emphasized medical urgency to address the heart transplant crisis by further dividing the previous sickest patient group into three subgroups. However, there is a significant debate on optimality and fairness of this policy because although it can help reduce pre‐transplant mortality, it may reduce post‐transplant survival. We undertake a rigorous study to address this debate by measuring the impacts of a variety of perspectives on the waiting list and patients. We show that the optimal policy of our proposed fluid model is a dynamic priority rule, and provide insight on the impact of fairness constraints on such priorities. We quantify the price that the society pays for following a medical urgency approach, which favors the sickest patients, compared to a utilitarian approach, which seeks to maximize total quality‐adjusted life years (QALYs). Our results, produced by a validated simulation model, reveal that the said price is 7.7% of total QALYs and increases to 11% by considering a broader regional sharing aligned with four‐hour heart cold ischemic time. We study other relevant objectives/measures in transplantation and our results show that the utilitarian policy outperforms the medical urgency policy in other measures as well. Our analysis provides novel insights on optimal patient allocation and sheds light on the debate around this challenging problem.
Occurrence of fatal police violence during pregnancy and hazard of preterm birth in California
Authors: Goin Dana E. , Gomez Anu Manchikanti , Farkas Kriszta , Duarte Catherine , Karasek Deborah , Chambers Brittany D. , Jackson Andrea V. , Ahern Jennifer
Published: March 2021

Background

Exposure to fatal police violence may play a role in population‐level inequities in risk for preterm delivery.

Objective

To evaluate whether exposure to fatal police violence during pregnancy affects the hazard of preterm delivery and whether associations differ by race/ethnicity and fetal sex.

Methods

We leveraged temporal variation in incidents of fatal police violence within census tracts to assess whether occurrence of fatal police violence in a person's tract during pregnancy was associated with increased hazard of extremely (20‐27 weeks), early (28‐31 weeks), moderate (32‐33 weeks), and late (32‐36 weeks) preterm delivery in California from 2007 to 2015. We used both death records and the Fatal Encounters database to identify incidents of fatal police violence. We estimated hazard ratios (HR) using time‐varying Cox proportional hazard models stratified by census tract, controlling for age, race/ethnicity, educational attainment, health insurance type, parity, and the year and season of conception. We further stratified by race/ethnicity and infant sex to evaluate whether there were differential effects by these characteristics.

Results

Exposure to an incident of fatal police violence was associated with a small increase in the hazard of late preterm birth using both the death records (N = 376,029; hazard ratio [HR] 1.05, 95% confidence interval [CI] 1.00, 1.10) and the Fatal Encounters data (N = 938,814; HR 1.03, 95% CI 1.00, 1.06). We also observed an association for moderate preterm birth in the Fatal Encounters data (HR 1.06, 95% CI 0.98, 1.15). We did not observe associations for early or extremely preterm birth in either data source. Larger relative hazards of moderate (HR 1.25, 95% CI 0.93, 1.68) and late preterm delivery (HR 1.18, 95% CI 1.05, 1.33) were observed among Black birth parents with female births in the Fatal Encounters data.

Conclusions

Preventing police use of lethal force may reduce preterm delivery in communities where such violence occurs.
Redox imbalance impedes photosynthetic activity in rice by disrupting cellular membrane integrity and induces programmed cell death under submergence
Authors: Basu Sahana , Kumari Surbhi , Kumar Pankaj , Kumar Gautam , Rajwanshi Ravi
Published: March 2021

Climate change negatively impacts the global hydrological resources leading to detrimental flood events. Submergence impedes the cellular membrane integrity, consequently affecting the membrane fluidity. Different abiotic stresses influence membrane lipid composition. Therefore, the remodeling of membrane lipids plays a major role in stress adaptation. Submergence‐induced membrane lipid peroxidation is well established in plants. However, dynamic changes in lipid composition for regulating submergence tolerance in rice remain so far unexplored. The present study explored the effect of submergence on the lipidomic profile of the Sub1 near‐isogenic lines (NILs) of rice, viz. Swarna, and Swarna Sub1 with contrasting submergence tolerance. The study also examined the association of lipidomic alteration with the membrane integrity and submergence tolerance. Submergence caused increased accumulation of reactive oxygen species (ROS), which was significantly higher in Swarna than Swarna Sub1. The lipid profile was also considerably altered under submergence. Following submergence, Swarna exhibited a significant decrease in phospholipid content accompanied by increased lipid peroxidation and electrolyte leakage. Furthermore, the disintegration of the thylakoid membrane resulted in a significant decrease in the chlorophyll content and photosynthesis rate under submergence. Submergence‐induced hypoxic condition also promoted starch depletion to fulfill the energy requirement. In contrast, submergence acclimation in Swarna Sub1 was associated with the shift to anaerobic respiration mediated by increased alcohol dehydrogenase (ADH) activity. Effective ROS detoxification in Swarna Sub1 facilitated by increased antioxidant enzyme activities contributed to the submergence tolerance by maintaining membrane integrity and photosynthetic activity. The present study established the direct association of lipid remodeling with membrane integrity, cell viability, and photosynthesis and also devised a crop model to reveal the molecular background of submergence tolerance in plants.
The dental plaque biofilm matrix
Authors: Jakubovics Nicholas S. , Goodman Steven D. , Mashburn‐Warren Lauren , Stafford Graham P. , Cieplik Fabian
Published: March 2021

The extracellular matrix is a critical component of microbial biofilms, such as dental plaque, maintaining the spatial arrangement of cells and coordinating cellular functions throughout the structure. The extracellular polymeric substances that comprise the matrix include carbohydrates, nucleic acids, proteins, and lipids, which are frequently organized into macromolecular complexes and/or are associated with the surfaces of microbial cells within the biofilm. Cariogenic dental plaque is rich in glucan and fructan polysaccharides derived from extracellular microbial metabolism of dietary sucrose. By contrast, the matrix of subgingival dental plaque is a complex mixture of macromolecules that is still not well understood. Components of the matrix escape from microbial cells during lysis by active secretion or through the shedding of vesicles and serve to anchor microbial cells to the tooth surface. By maintaining the biofilm in close association with host tissues, the matrix facilitates interactions between microorganisms and the host. The outcome of these interactions may be the maintenance of health or the development of dental disease, such as caries or periodontitis. The matrix affords microbial cells protection against chemical and physical insults and hinders the eradication of pathogenic dental plaque. Therefore, strategies to control the matrix are critical to maintain oral health. This review discusses recent advances in our understanding of the composition, origins, and function of the dental plaque matrix, with a focus on subgingival dental plaque. New strategies to control subgingival dental plaque based on targeting the biofilm matrix are also considered.
Maintaining homeostatic control of periodontal epithelial tissue
Authors: Chang Ana M. , Kantrong Nutthapong , Darveau Richard P.
Published: March 2021

Years of coevolution with resident microbes has made them an essential component of health. Yet, little is known about oral commensal bacteria’s contribution to and role in the maintenance of oral health and homeostasis. Commensal bacteria are speculated to play a host protective role in the maintenance of health. In this review, we describe and provide examples of the coordinate regulation that occurs between oral commensal bacteria and the host innate immune response to modulate and maintain oral homeostasis.
Peri‐implantitis is not periodontitis: Scientific discoveries shed light on microbiome‐biomaterial interactions that may determine disease phenotype
Authors: Kotsakis Georgios A. , Olmedo Daniel G.
Published: March 2021

Peri‐implantitis is an immune‐mediated biological complication that is attributed to bacterial biofilms on the implant surface. As both periodontitis and peri‐implantitis have similar inflammatory phenotypes when assessed cross‐sectionally, treatment protocols for peri‐implantitis were modeled according to those used for periodontitis. However, lack of efficacy of antimicrobial treatments targeting periodontal pathogens coupled with recent discoveries from open‐ended microbial investigation studies create a heightened need to revisit the pathogenesis of peri‐implantitis compared with that of periodontitis. The tale of biofilm formation on intraoral solid surfaces begins with pellicle formation, which supports initial bacterial adhesion. The differences between implant‐ and tooth‐bound biofilms appear as early as bacterial adhesion commences. The electrostatic forces and ionic bonding that drive initial bacterial adhesion are fundamentally different in the presence of titanium dioxide or other implant alloys vs mineralized organic hydroxyapatite, respectively. Moreover, the interaction between metal surfaces and the oral environment leads to the release of implant degradation products into the peri‐implant sulcus, which exposes the microbiota to increased environmental stress and may alter immune responses to bacteria. Clinically, biofilms found in peri‐implantitis are resistant to beta‐lactam antibiotics, which are effective against periodontal communities even as monotherapies and demonstrate a composition different from that of biofilms found in periodontitis; these facts strongly suggest that a new model of peri‐implant infection is required.
Does value‐added tax reform boost firms’ domestic value added in exports? Evidence from China
Authors: Wu Songbo , Lu Yue , Lv Xiaofeng
Published: March 2021

We explore the effect of value‐added tax (VAT) on domestic value added in exports where VAT is incorporated into a theoretical model to analyze its distortion on intra‐firm resource allocation. The VAT pilot reform in the three northeast provinces of China in 2004 provided a natural experiment which generated significant effective VAT rate differences due to deduction policies. We utilize the reform as an exogenous shock to identify its effect on the domestic value added ratio (DVAR) in exports at the firm level. Empirical results show that the reform has significantly increased the firms' DVAR by allowing more deduction of fixed asset purchases that lowers the effective VAT rates of the affected firms, which confirm the findings of our conceptual framework. This effect is greater for large and medium‐sized firms than for small and microscale firms. The VAT reform in 2004 has significant effect on the DVAR of state‐owned enterprises and domestic private firms, but not for foreign invested firms. The reform also has higher effect for firms from higher market concentration sectors.
CMV infection, valganciclovir exposure, and the risk of BK viremia and associated nephropathy after kidney transplantation: Is there a link?
Authors: Rodríguez‐Goncer Isabel , Ruiz‐Ruigómez María , López‐Medrano Francisco , Corbella Laura , Polanco Natalia , González Monte Esther , San Juan Rafael , Ruiz‐Merlo Tamara , Parra Patricia , Folgueira Lola , Andrés Amado , Aguado José María , Fernández‐Ruiz Mario
Published: March 2021

Background

Immunomodulatory effects attributable to cytomegalovirus (CMV) would predispose to BK polyomavirus (BKPyV) infection after kidney transplantation (KT), although available evidence is conflicting. It has been suggested that (val)ganciclovir therapy may increase the risk of BKPyV viremia and BKPyV‐associated nephropathy (BKPyVAN) as a result of drug‐induced T‐cell impairment.

Methods

We investigated whether CMV replication and/or (val)ganciclovir exposure (either as prophylaxis or treatment) were associated with the development of BKPyV viremia or BKPyVAN in a prospective cohort of 399 KT recipients. CMV infection (any level or high‐level viremia and area under the curve of DNAemia) and (val)ganciclovir exposure (any duration of therapy and cumulative days of treatment) during the first post‐transplant year were explored through separate landmark survival analyses.

Results

Cumulative incidence of BKPyV viremia and BKPyVAN after a median follow‐up of 551 days was 23.1% and 2.5%, respectively. One‐year rates of CMV infection and (val)ganciclovir therapy were 47.4% and 54.1%, respectively. No differences were observed in BKPyV viremia‐ or BKPyVAN‐free survival according to previous CMV infection or (val)ganciclovir exposure in any of the landmark analyses. Adjusted Cox models confirmed this lack of association.

Conclusion

Our findings do not confirm the existence of a relevant impact of CMV infection or (val)ganciclovir therapy on the risk of post‐transplant BKPyV events.
The transcriptomic landscapes of rice cultivars with diverse root system architectures grown in upland field conditions
Authors: Kawakatsu Taiji , Teramoto Shota , Takayasu Satoko , Maruyama Natsuko , Nishijima Ryo , Kitomi Yuka , Uga Yusaku
Published: March 2021

Root system architecture affects plant drought resistance and other key agronomic traits such as lodging. However, although phenotypic and genomic variation has been extensively analyzed, few field studies have integrated phenotypic and transcriptomic information, particularly for below‐ground traits such as root system architecture. Here, we report the phenotypic and transcriptomic landscape of 61 rice (Oryza sativa) accessions with highly diverse below‐ground traits grown in an upland field. We found that four principal components explained the phenotypic variation and that accessions could be classified into four subpopulations (indica, aus, japonica and admixed) based on their tiller numbers and crown root diameters. Transcriptome analysis revealed that differentially expressed genes associated with specific subpopulations were enriched with stress response‐related genes, suggesting that subpopulations have distinct stress response mechanisms. Root growth was negatively correlated with auxin‐inducible genes, suggesting an association between auxin signaling and upland field conditions. A negative correlation between crown root diameter and stress response‐related genes suggested that thicker crown root diameter is associated with resistance to mild drought stress. Finally, co‐expression network analysis implemented with DNA affinity purification followed by sequencing analysis identified phytohormone signaling networks and key transcription factors negatively regulating crown root diameter. Our datasets provide a useful resource for understanding the genomic and transcriptomic basis of phenotypic variation under upland field conditions.
Association of Veterinary Hematology and Transfusion Medicine (AVHTM) transfusion reaction small animal consensus statement (TRACS). Part 3: Diagnosis and treatment
Authors: Odunayo Adesola , Nash Katherine J , Davidow Elizabeth B. , Blois Shauna L. , Goy‐Thollot Isabelle , Harris Lauren , Humm Karen , Musulin Sarah , Sharp Claire R. , Spada Eva , Thomason John , Walton Jenny , Jane Wardrop K.
Published: March 2021

Objective

To systematically review available evidence to develop guidelines for diagnosis and treatment of transfusion‐associated reactions in dogs and cats.

Design

Standardized and systemic evaluation of the literature (identified through Medline via PubMed and Google Scholar searches) was carried out for identified transfusion reaction types in dogs and cats. The available evidence was evaluated using PICO (Population, Intervention, Comparison, Outcome) questions generated for each reaction type. The evidence was categorized by level of evidence (LOE) and quality (Good, Fair, or Poor). Guidelines, diagnostic, and treatment algorithms were generated based on the evaluation of the evidence. Consensus on the final guidelines was achieved through Delphi‐style surveys. Draft recommendations were disseminated through veterinary specialty listservs for review and comments, which were evaluated and integrated prior to final publication.

Results

Medline via PubMed and Google Scholar databases were searched. There were 14 Population Intervention Comparison Outcome questions identified and corresponding worksheets were developed focusing on the diagnosis and treatment of transfusion‐associated reactions in dogs and cats. Fourteen guidelines and four algorithms were developed with a high degree of consensus.

Conclusions

This systematic evidence evaluation process yielded recommended diagnostic and treatment algorithms for use in practice. However, significant knowledge gaps were identified, demonstrating the need for additional research in veterinary transfusion medicine.
Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS) Part 2: Prevention and monitoring
Authors: Davidow Elizabeth B. , Blois Shauna L. , Goy‐Thollot Isabelle , Harris Lauren , Humm Karen , Musulin Sarah , Nash Katherine J. , Odunayo Adesola , Sharp Claire R. , Spada Eva , Thomason John , Walton Jenny , Wardrop K. Jane
Published: March 2021

Objective

To systematically review available evidence to develop guidelines for the prevention of transfusion reactions and monitoring of transfusion administration in dogs and cats.

Design

Evidence evaluation of the literature (identified through Medline searches through Pubmed and Google Scholar searches) was carried out for identified transfusion reaction types in dogs and cats. Evidence was evaluated using PICO (Population, Intervention, Comparison, Outcome) questions generated for each reaction type. Evidence was categorized by level of evidence (LOE) and quality (Good, Fair, or Poor). Guidelines for prevention and monitoring were generated based on the synthesis of the evidence. Consensus on the final recommendations and a proposed transfusion administration monitoring form was achieved through Delphi‐style surveys. Draft recommendations and the monitoring form were made available through veterinary specialty listservs and comments were incorporated.

Results

Twenty‐nine guidelines and a transfusion administration monitoring form were formulated from the evidence review with a high degree of consensus

Conclusions

This systematic evidence evaluation process yielded recommended prevention and monitoring guidelines and a proposed transfusion administration form. However, significant knowledge gaps were identified, demonstrating the need for additional research in veterinary transfusion medicine.
Construir la paz en condiciones adversas
Authors: Jaramillo Marín Jefferson , Salgado Ruíz Henry , Eslava Rincón Julia Isabel , Vega Romero Román Rafael , Bedoya Calvo Isabel Cristina , Caviedes Pinilla Mauricio , Suelt Cock Vanessa Andrea
Published: March 2021

No siempre las políticas, leyes y planes de ordenamiento en Colombia se ajustan a las necesidades de un gran número de comunidades que se encuentran en situación de vulnerabilidad frente a la salud, la educación y la seguridad. Ante este panorama, varias comunidades han generado respuestas locales que proponen nuevas formas de entender la organización económica, la sostenibilidad ambiental, y el bienestar territorial, ajustadas a las demandas de espacios inmersos en conflictos económicos, sociales y políticos. Construir la paz en condiciones adversas reúne seis capítulos que reflexionan sobre la satisfacción de los derechos civiles, políticos, territoriales, sociales y económicos en algunas regiones colombianas, a partir de procesos organizativos comunitarios que permiten unir la teoría con la práctica. Sus autores y autoras, motivados por un deseo de generar cambios sociales concretos desde la reflexión académica, proponen un mapa de ruta en el que el cuestionamiento de la teoría permite encontrar nuevas propuestas y aproximaciones a los obstáculos que enfrentan un gran número de sociedades rurales en el país.
Estrategias comunicativas para enfrentar las dificultades al hablar en inglés en una universidad pública de Colombia
Authors: Gómez Juan Fernando , Restrepo Jorge Emiro , Parra Fernández Eleonora
Published: March 2021

Las estrategias comunicativas pueden ser utilizadas para enfrentar los problemas que surgen durante la interacción oral en el aula. El estudio plantea dos objetivos: identificar las estrategias más empleadas por estudiantes universitarios para el manejo las dificultades en la comunicación oral en inglés, y describir las diferencias en la frecuencia de uso de estas estrategias entre ambos niveles y sexos. La investigación corresponde a un enfoque cuantitativo, de tipo descriptivo, con un diseño trasversal, con una población de 542 estudiantes. Las estrategias más utilizadas por esta muestra son las de intento de pensar en inglés y de reducción y alteración del mensaje. Se halló una diferencia entre ambos niveles en las estrategias orientadas hacia la adecuación. Por otro lado, los hombres hacen mayor uso de las estrategias socio afectivas, mientras que las mujeres utilizan más las de abandono del mensaje.
La leche y la sangre, el cuerpo y el espíritu: significaciones de lo corporal en La teta asustada, de Claudia Llosa
Authors: Finol José Enrique , Cabrejo José Carlos
Published: March 2021

En este trabajo presentamos los resultados de una investigación sobre la película La teta asustada (2009), de la directora peruana Claudia Llosa. Se propone una aproximación novedosa al análisis e interpretación del film, de modo que puedan destacarse aspectos escasamente tratados en la bibliografía sobre el tema. Partimos del principio según el cual el cuerpo es el elemento fundamental en la semiotización del mundo, un aspecto que la película desarrolla extensa e intensamente. Se propone una clasificación compuesta por cinco tipos de corporalidades (espacial, temporal, sexual, vegetal y vital), las cuales configuran un sentido específico de la corporeidad, concepto entendido como el conjunto de los imaginarios asociados al cuerpo, en un contexto y momento histórico determinados.
The Theory of Plasticity—An Outline of Work Done in Russia
Authors: Sokolovsky W. W.
Published: March 2021

The theory of plasticity as an important part of the mechanics of continuous materials has occupied the attention of many Russian workers in recent years. In the first paper in this field published in 1935, by S. Sobolev (17) the propagation in time of a plastic zone was investigated around a circular hole in an infinite plate. The plastic zone was assumed to have a polar symmetric shape. Based on the works of L. Prandtl, Th. von Kármán, R. von Mises, H. Hencky, A. Nadai, and others, more recently, a group of young Russian engineers have investigated further the theory of plasticity and added many new developments to it. While the investigations abroad and in Europe, outside of Russia, were being aimed at establishing the validity of the theory of plasticity, most of the papers appearing in the literature in Russia were devoted to the solutions of concrete problems. This review does not attempt to discuss broadly the work done in the theory of plasticity. The author confines himself to certain parts of the theory which have been developed in Russia. Naturally those closest to his own scientific interests have been selected for treatment.
Design of Crankpins for Locomotives
Authors: Horger O. J. , Cantley W. I.
Published: March 2021

This progress report presents the results of a fatigue investigation made on full-size 9 1/2-in-diam crankpins by the Association of American Railroads. The primary object of this study was to develop an improved crankpin-and-wheel assembly which will alleviate crankpin fatigue failures occurring in the wheel-fit portion in service. A total of 50 full-size crankpin-and-wheel assemblies were tested, using four different types of pins. All pins were of plain-carbon steel, normalized and tempered, having a carbon content of 0.52 per cent and manganese of 0.80 per cent. Large double-ended cantilever-type fatigue machines subjected the crankpin-and-wheel assemblies to rotating-hending stresses. The fatigue resistance of the conventional assembly, against the crankpin breaking off in the wheel fit, may be expressed as 100 per cent. The other three types of pins gave values of 136, 146, and over 200 per cent (Table 7). Even with this greatly improved breaking-off strength, shallow fatigue cracks were found to initiate in the wheel-fit portion of all four types of pins at bending stresses much below what was required to propagate the cracks to complete fracture.
Measurements of Friction in a Pipe for Subsonic and Supersonic Flow of Air
Authors: Keenan J. H. , Neumann E. P.
Published: March 2021

The apparent friction coefficient was determined experimentally for the flow of air through smooth pipes at subsonic and supersonic velocities. Values of the Mach number ranged from 0.27 to 3.87, and of Reynolds number from 1 × 105 to 8.7 × 105. In supersonic flow the results were found to be strongly influenced by the presence of oblique shocks formed at the junction of nozzle and pipe. The effect of these shocks on the coefficient of friction was determined. Nozzle forms were devised which eliminated the shocks and their effects. It was found that at distances from the pipe inlet greater than 50 diam the apparent coefficient of friction for compressible flow at Mach numbers greater or less than 1 is approximately equal, for equal Reynolds numbers, to the coefficient of friction for incompressible flow with completely developed boundary layer. Mach numbers greater than 1 are rarely maintained for lengths greater than 50 diam. For attainable lengths, the coefficient of friction is a function of the ratio of length to diameter and the Reynolds number, with the Mach number at entrance determining the maximum attainable length.
General Stress-Strain Laws of Elasticity and Plasticity
Authors: Gleyzal A.
Published: March 2021

The stress-strain laws discussed in this paper apply to problems where the material is elastic in some regions and plastic in others, for example, in a plastic-torsion problem or in a plastic-bending problem. These laws have experimental verification for metals in cases where strains are small and stresses and strains are either monotonically increasing or monotonically decreasing at any one point.
Reconstructing Compressor Non-Uniform Circumferential Flow Field From Spatially Undersampled Data—Part 1: Methodology and Sensitivity Analysis
Authors: Lou Fangyuan , Key Nicole L.
Published: March 2021

The flow field in a compressor is circumferentially non-uniform due to the wakes from upstream stators, the potential field from both upstream and downstream stators, and blade row interactions. This non-uniform flow impacts stage performance as well as blade forced vibrations. Historically, experimental characterization of the circumferential flow variation is achieved by circumferentially traversing either a probe or the stator rows. This involves the design of complex traverse mechanisms and can be costly. To address this challenge, a novel method is proposed to reconstruct compressor non-uniform circumferential flow field using spatially under-sampled data points from a few probes at fixed circumferential locations. The paper is organized into two parts. In the present part of the paper, details of the multi-wavelet approximation for the reconstruction of circumferential flow and use of the particle swarm optimization algorithm for selection of probe positions are presented. Validation of the method is performed using the total pressure field in a multi-stage compressor representative of small core compressors in aero engines. The circumferential total pressure field is reconstructed from eight spatially distributed data points using a triple-wavelet approximation method. Results show good agreement between the reconstructed and the true total pressure fields. Also, a sensitivity analysis of the method is conducted to investigate the influence of probe spacing on the errors in the reconstructed signal.
Uncertainty Quantification of Spalart–Allmaras Turbulence Model Coefficients for Compressor Stall
Authors: He Xiao , Zhao Fanzhou , Vahdati Mehdi
Published: March 2021

The turbulence model in Reynolds-averaged Navier–Stokes simulations is crucial in the prediction of the compressor stall margin. In this paper, parametric uncertainty of the Spalart–Allmaras turbulence model in predicting two-dimensional airfoil stall and three-dimensional compressor stall has been investigated using a metamodel-based Monte Carlo method. The model coefficients are represented by uniform distributions within physically acceptable ranges. The quantities of interest include characteristic curves, stall limit, blockage size, and turbulence magnitude. Results show that the characteristics can be well predicted in the stable flow range, but the inaccuracy and the uncertainty increase when approaching stall. The stall point of the airfoil can be enveloped by the parametric uncertainty range, but that of the rotor cannot. Sensitivity analyses identified the crucial model coefficients to be source related, where an increase in the predicted turbulence level will delay the onset of stall. Such results imply that implementing new turbulence production terms with respect to the rotor-specific flow features is likely to improve the model accuracy. The findings in this paper not only provide engineering rules of thumb for the model users but also guide the future implementation of a data-driven turbulence model for the model developers.
Numerical and Experimental Study on Rotating Stall in Industrial Centrifugal Compressor
Authors: Miura Toshimasa , Yamashita Hideaki , Takeuchi Ryota , Sakai Naoto
Published: March 2021

Centrifugal compressors employed in the oil and gas industry are operated at high gas pressure conditions and are used in a wide operation range. Accurate prediction of the rotating stall and the destabilizing aerodynamic force is one of the key technologies for these compressors. The aim of this study is to establish a method of accurately predicting the inception of rotating stall and its effect on shaft vibration. To achieve this, numerical investigations are carried out by unsteady flow and rotordynamic simulations. To validate the accuracy, an experiment is carried out at relatively high gas pressure conditions. In the first part of the study, the accuracy of compressor performance prediction is studied by steady computational fluid dynamics (CFD) simulation. It is found that by taking the wall roughness effect into account, the predicted performance shows good agreement with the experimental result. In the second part of the study, the accuracy of predicting the rotating stall is studied. In the experiment, two types of rotating stalls are measured. One is a multiple-cell stall induced in the vaneless diffuser and the other is a one-cell stall induced in the impeller. It is found that the simulation can predict the inception of the rotating stall with relatively high accuracy as the predicted results show good agreement with the experimental results in terms of cell count, rotation speed, pressure fluctuation level, and the effect on shaft vibration. Through this study, the effectiveness of simulation is validated for the stall and vibration prediction.
Application of Scale Adaptive Simulation Model to Studying Cooling Characteristics of a High Pressure Turbine Blade Cutback Trailing Edge With Different Cooling Configurations
Authors: Li Yue-feng , Xu Hua-zhao , Wang Jian-hua , Song Wei , Wang Ming , Liu Tai-qiu , Wang Xu
Published: March 2021

Effective cooling structure design in the trailing edge (TE) of a high pressure turbine (HPT) blade is essential to increase turbine efficiency and maintain structural integrity. To obtain efficient cooling structures and understand clearly cooling mechanism, this paper adopted numerical simulation methods to investigate fluid flow and cooling characteristics in detail downstream of an HPT blade TE cutback region. The effects of typical TE configurations on cutback cooling performance are investigated including three types of internal turbulators (cylindrical pin fins and elliptic pin fins arranged in streamwise and spanwise orientations), the cutback with/without land extensions and three kinds of ejection lip profiles (one straight lip shape marked as “A” and two rounded lip shapes marked as “B” and “C,” respectively). The scale adaptive simulation (SAS) is implemented to study the complex unsteady mixing process downstream of the cutback under operating condition of blowing ratio M = 0.65. The results from the shear stress transport (SST) k–ω model are compared as well. SAS is capable to reproduce the periodical vortex shedding phenomena and resolve the vortices coherent structures. Compared with the experimental data, SAS provides more accurate predictions in terms of laterally averaged adiabatic cooling effectiveness ηaw and discharge coefficient Cd than the SST k–ω model. At the rear part of the cutback surface, large deterioration in ηaw is predicted by SAS for all configurations, but ηaw is considerably overpredicted by the SST k–ω model except for the case of elliptic pin fins with spanwise orientation. The elliptic pin fins with streamwise orientation significantly improve ηaw at the rear part of the cutback surface over the baseline model with cylindrical pin fins and slightly increase Cd. However, the elliptic pin fins with spanwise orientation drastically reduce the ηaw and Cd. Downstream of the cutback, the coherent structures are strongly disturbed and become chaotic compared with the TE with cylindrical and streamwise oriented elliptic pin fins. The application of land extensions only causes an evident change to the coherent structure immediate downstream of the lip and slightly improves ηaw and reduces Cd over the baseline model at the rear part of the cutback surface. Rounded lip shapes B and C also show an obvious increase in ηaw at the rear part of the cutback surface but only a minor increase in Cd compared with the straight lip shape A. The rounded lip helps the coolant diffuse into the TE cutback and reduce the intensity of mixing. Due to larger rounding radius of shape B, the cooling effectiveness predicted by shape B is slightly better than shape C.
Effect of metal contacts on (100) β-Ga2O3 Schottky barriers
Authors: Lyle Luke A. M. , Jiang Kunyao , Favela Elizabeth V. , Das Kalyan , Popp Andreas , Galazka Zbigniew , Wagner Guenter , Porter Lisa M.
Published: March 2021

The Schottky barriers of Ti, Mo, Co, Ni, Pd, and Au on (100) β-Ga2O3 substrates were analyzed using a combination of current-voltage (J-V), capacitance-voltage (C-V), and current-voltage-temperature (J-V-T) measurements. Near-ideal, average ideality factors for Ti, Mo, Co, and Ni were 1.05–1.15, whereas higher ideality factors (∼1.3) were observed for Pd and Au contacts. Barrier heights ranging from 0.60 to 1.20 eV were calculated from J-V measurements for the metals with low ideality factors. C-V measurements of all Schottky metals were conducted and yielded average barrier heights ranging from 0.78 to 1.98 eV. J-V-T measurements of Ti and Co diodes yielded barrier heights of 0.81 and 1.35 eV, respectively. The results reveal a strong positive correlation between the calculated Schottky barrier heights and the metal work functions: the index of interface behavior, S = 0.70, 0.97, and 0.81 for J-V, C-V, and J-V-T data, respectively.
Fundamental frequency range and other acoustic factors that might contribute to the clear-speech benefit
Authors: Han Heekyung J. , Munson Benjamin , Schlauch Robert S.
Published: March 2021

The main goal of the present study was to assess the role of the fundamental frequency (F0) range on the clear-speech benefit. Conversational- and clear-speech sentences were recorded for four male speakers: the speakers' clear-speech productions had slower speaking rates, wider F0 range, more high-frequency energy, expanded vowel space, and higher vocal intensity level relative to their conversational-speech productions. To examine if F0 range contributes to the clear-speech benefit, the F0 range of clear-speech sentences was compressed to match that of the speakers' conversational-speech sentences. Fifteen listeners were presented with conversational, clear, and F0-compressed sentences in sustained speech-shaped noise. All talkers elicited substantial intelligibility benefits (keyword percent correct) from clear and F0-compressed speech when compared with conversational speech. There was no significant difference in performance between clear and F0-compressed speech. These results leave open the possibility that a clear-speech benefit could be a result of its F0 contours rather than its wide F0 range. Intelligibility predictions based on acoustic characteristics of clear speech, specifically high-frequency emphasis and pauses, accounted for either small or negligible amounts of the clear-speech benefit.
Fluid-structure-acoustic interactions in an ex vivo porcine phonation model
Authors: Semmler Marion , Berry David A. , Schützenberger Anne , Döllinger Michael
Published: March 2021

In the clinic, many diagnostic and therapeutic procedures focus on the oscillation patterns of the vocal folds (VF). Dynamic characteristics of the VFs, such as symmetry, periodicity, and full glottal closure, are considered essential features for healthy phonation. However, the relevance of these individual factors in the complex interaction between the airflow, laryngeal structures, and the resulting acoustics has not yet been quantified. Sustained phonation was induced in nine excised porcine larynges without vocal tract (supraglottal structures had been removed above the ventricular folds). The multimodal setup was designed to simultaneously control and monitor key aspects of phonation in the three essential parts of the larynx. More specifically, measurements will comprise (1) the subglottal pressure signal, (2) high-speed recordings in the glottal plane, and (3) the acoustic signal in the supraglottal region. The automated setup regulates glottal airflow, asymmetric arytenoid adduction, and the pre-phonatory glottal gap. Statistical analysis revealed a beneficial influence of VF periodicity and glottal closure on the signal quality of the subglottal pressure and the supraglottal acoustics, whereas VF symmetry only had a negligible influence. Strong correlations were found between the subglottal and supraglottal signal quality, with significant improvement of the acoustic quality for high levels of periodicity and glottal closure.