bluuebunny/crossref_metadata_2025 huggingface dataset:
OsGCD1 is essential for rice fertility and required for embryo dorsal‐ventral pattern formation and endosperm development
Authors: Huang Xiaorong , Peng Xiongbo , Sun Meng‐Xiang
Published: June 2017

Rice fertility is critical for rice reproduction and is thus a focus of interest. Most studies have addressed male sterility and its relation to rice production. The mechanisms of regulation of embryogenesis and endosperm development are essential for rice reproduction, but remain largely unknown.

Here, we report a functional analysis of the rice gene OsGCD1, which encodes a highly conserved homolog of Arabidopsis GCD1 (GAMETE CELLS DEFECTIVE1). OsGCD1 mutants were generated using the CRISPR/Cas9 system and subjected to functional analysis.

The homozygote mutants cannot be obtained, whereas heterozygotes showed altered phenotypes. In the majority of aborted seeds, the endosperm nucleus divided a limited number of times. The free nuclei were distributed only at the micropylar end of embryo sacs, and their oriented positioning was blocked. In addition, aleurone differentiation was interrupted. The embryo developed slowly, and pattern formation, particularly the dorsal‐ventral pattern and symmetry establishment, of embryos was disturbed. Thus, the embryos showed various morphological and structural dysplasias.

Our findings reveal that OsGCD1 is essential for rice fertility and is required for dorsal‐ventral pattern formation and endosperm free nucleus positioning, suggesting a critical role in sexual reproduction of both monocotyledon and dicotyledon plants.
Role of tree size in moist tropical forest carbon cycling and water deficit responses
Authors: Meakem Victoria , Tepley Alan J. , Gonzalez‐Akre Erika B. , Herrmann Valentine , Muller‐Landau Helene C. , Wright S. Joseph , Hubbell Stephen P. , Condit Richard , Anderson‐Teixeira Kristina J.
Published: June 2017

Drought disproportionately affects larger trees in tropical forests, but implications for forest composition and carbon (C) cycling in relation to dry season intensity remain poorly understood.

In order to characterize how C cycling is shaped by tree size and drought adaptations and how these patterns relate to spatial and temporal variation in water deficit, we analyze data from three forest dynamics plots spanning a moisture gradient in Panama that have experienced El Niño droughts.

At all sites, aboveground C cycle contributions peaked below 50‐cm stem diameter, with stems ≥ 50 cm accounting for on average 59% of live aboveground biomass, 45% of woody productivity and 49% of woody mortality. The dominance of drought‐avoidance strategies increased interactively with stem diameter and dry season intensity. Although size‐related C cycle contributions did not vary systematically across the moisture gradient under nondrought conditions, woody mortality of larger trees was disproportionately elevated under El Niño drought stress.

Thus, large (> 50 cm) stems, which strongly mediate but do not necessarily dominate C cycling, have drought adaptations that compensate for their more challenging hydraulic environment, particularly in drier climates. However, these adaptations do not fully buffer the effects of severe drought, and increased large tree mortality dominates ecosystem‐level drought responses.
Effects of intraoperative liberal fluid therapy on postoperative nausea and vomiting in children—A randomized controlled trial
Authors: Ashok Vighnesh , Bala Indu , Bharti Neerja , Jain Divya , Samujh Ram
Published: June 2017

Background

Postoperative nausea and vomiting (PONV) is one of the most distressing complications following surgery. Supplemental perioperative fluid therapy might be an effective strategy to reduce PONV in children.

Objectives

The study was conducted to evaluate the effects of intraoperative liberal fluid therapy with crystalloids on PONV in children.

Methods

In this randomized trial, a total of 150 children of 3‐7 years undergoing lower abdominal and penile surgery under general anesthesia were randomly assigned into two groups. “Restricted group” received 10 mL kg−1 h−1 and “Liberal group” received 30 mL kg−1 h−1 infusion of Ringer's lactate solution intraoperatively. All patients received a caudal block and intravenous paracetamol for analgesia. No opioids and muscle relaxants were used. All episodes of nausea‐vomiting and the requirement of rescue antiemetic were assessed during 24 hours postoperatively.

Results

The incidence of PONV was significantly less in the liberal group patients as compared to the restricted group; 33 (45.8%) patients in the restricted group had vomiting as compared to 20 (27.4%) patients in the liberal group (RR 0.59, 95% CI: 0.38‐0.93, P=.021). The adjusted odds ratio of PONV for the liberal group vs restricted group was 2.24 (95% CI: 1.12‐4.48, P=.022). The incidence of fluid intake during the first 6 postoperative hours was significantly higher in the restricted group patients; 60 (83%) children in the restricted group complained of thirst as compared to 12 (17%) children in the liberal group (RR 0.19, 95% CI: 0.18‐0.33, P=.0001). The parents of the liberal group were more satisfied as compared to the restricted group (mean difference −0.9, 95% CI: −1.8, −0.1, P=.04). None of the children had any complication attributed to the liberal fluid therapy.

Conclusion

Liberal intraoperative fluid therapy was found to be effective in reducing PONV in children undergoing lower abdominal surgery.
Emotion dysregulation, symptoms, and interpersonal problems as independent predictors of a broad range of personality disorders in an outpatient sample
Authors: Dimaggio Giancarlo , Popolo Raffaele , Montano Antonella , Velotti Patrizia , Perrini Filippo , Buonocore Luisa , Garofalo Carlo , D'Aguanno Mario , Salvatore Giampaolo
Published: June 2017

Emotion dysregulation (ED) is considered a hallmark of borderline personality disorder and is prominent in other personality disorders (PDs). Its presence and contribution to personality pathology need to be explored in the whole range of PDs. In this study, we investigated the association of ED with the whole range of PD traits, symptoms, and interpersonal problems and then investigated whether ED had a unique contribution in predicting the different PDs. A sample of 478 treatment‐seeking outpatients was interviewed with the SCID‐II. The patients were then tested for symptoms (SCL‐90‐R), interpersonal problems (IIP‐32), and ED (DERS). Results: ED correlated with the large majority of PDs and with symptoms and interpersonal problems. Regression showed how ED explained a unique part of the variance for many PDs. ED appears to be a relevant feature of pathology in many PDs; with replication, it can be considered a treatment target in this population.

Practitioner points

Emotion dysregulation is present in many personality disorders.

Emotion dysregulation is not just explained by heightened symptoms and interpersonal problems in personality disorders.

Emotion dysregulation could be considered a treatment target in personality disorders other than borderline.
Adolescent perfectionism: Structural features of the Frost Multidimensional Perfectionism Scale and correlates with attachment and psychopathology
Authors: Taylor Emily P. , Couper Rachel , Butler Carolyn Maeve
Published: June 2017

Objectives

Perfectionism is recognized as a significant risk factor for psychopathology. Emerging research links attachment to perfectionism in adult and college‐age samples. The Frost Multidimensional Perfectionism Scale (FMPS) has been used in adults and adolescents with a variety of factor structures found. This study sought to establish the factor structure in a general adolescent sample prior to testing for associations between perfectionism, attachment, and psychopathology in the same sample.

Design

A cross‐sectional survey design was used. Confirmatory factor analysis, and correlational and regression analyses were employed.

Methods

A total of 290 adolescents, aged 12–18 years, were recruited from a state secondary school. All completed the FMPS along with brief measures of attachment and psychopathology.

Result

Exploratory and confirmatory factor analyses failed to replicate previously published models, and a new six‐item, 1‐factor model representing perfectionism was found instead. This new variable was then used to establish a role for perfectionism and attachment anxiety in predicting internalizing problems. Perfectionism also correlated with conduct problems and hyperactivity.

Conclusion

This study established a novel factor structure for the FMPS, allowing proof of principle of the role of perfectionism in a relationship with attachment and psychopathology, which after replication, may inform new interventions for perfectionism. Caution is noted about the use of extant perfectionism measures that are not properly developmentally informed and which do not capture the dynamic nature of adolescence and adolescent perfectionism.

Practitioner points

Perfectionism is a feature of adolescent psychopathology, including internalizing and externalizing problems.

Perfectionism is associated with attachment anxiety and together contributes to internalizing problems.

Current conceptualizations of perfectionism may not capture the specific developmental and dynamic aspects of adolescence and should not be regarded as a stable personality trait.
Applications of ionizing radiation for the control of postharvest diseases in fresh produce: recent advances
Authors: Jeong M.‐A. , Jeong R.‐D.
Published: June 2017

Postharvest diseases cause considerable losses to harvested fruits and vegetables worldwide. In addition to various treatments to control postharvest losses caused by pathogens, the global trend is shifting toward more ecofriendly alternatives safer to human health. Thus far, the main approach to postharvest disease control has mostly relied on the use of chemicals. However, the intense use of chemical fungicides has caused side effects such as environmental issues and evolution of fungicide‐resistant isolates. With increasing demand for the use of non‐chemicals, ionizing radiation has been investigated for application in many aspects of postharvest treatment, especially as an approach with significant potential for the control of postharvest disease. Recently, a number of more or less technologically advanced methodologies, e.g. irradiation combined with other types of treatments and induced disease‐resistance, have been developed to control postharvest diseases as well as to increase the quality and storage life of fresh commodities. Challenges for future application of irradiation in fresh produce are the cost, lack of irradiation facilities, lack of knowledge about optimal conditions for different commodities, and lack of acceptance of irradiated fresh produce. This review aims to document the advances in understanding of the effects of irradiation on postharvest disease, the possible modes of action, and the perspectives in commercial use.
Antipsychotic prescription and mortality in hospitalized older persons
Authors: Chiesa Deborah , Marengoni Alessandra , Nobili Alessandro , Tettamanti Mauro , Pasina Luca , Franchi Carlotta , Djade Codjo D. , Corrao Salvatore , Salerno Francesco , Marcucci Maura , Romanelli Giuseppe , Mannucci Pier Mannuccio ,   REPOSI Investigators
Published: June 2017

Background

Recent scientific reports have shown that older persons treated with antipsychotics for dementia‐related behavioural symptoms have increased mortality. However, the impact of these drugs prescribed during hospitalization has rarely been assessed. We aimed to investigate whether antipsychotics are associated with an increased risk of mortality during hospitalization and at 3‐month follow‐up in elderly inpatients.

Methods

We analyzed data gathered during two waves (2010 and 2012) by the REPOSI (Registro Politerapie Società Italiana Medicina Interna). All new prescriptions of antipsychotic drugs during hospitalization, whether maintained or discontinued at discharge, were collected, and logistic regression models were used to analyze their association with in‐hospital and 3‐month mortality. Covariates were age, sex, the Short Blessed Test (SBT) score, and the Cumulative Illness Rating Scale.

Results

Among 2703 patients included in the study, 135 (5%) received new prescriptions for antipsychotic drugs. The most frequently prescribed antipsychotic during hospitalization and eventually maintained at discharge was haloperidol (38% and 36% of cases, respectively). Patients newly prescribed with antipsychotics were older and had a higher Cumulative Illness Rating Scale comorbidity index both at admission and at discharge compared to those who did not receive a prescription. Of those prescribed antipsychotics, 71% had an SBT score ≥10 (indicative of dementia), 12% had an SBT score of 5–9 (indicative of questionable dementia); and 17% had an SBT score <5 (indicative of normal cognition). In‐hospital mortality was slightly higher in patients prescribed antipsychotic drugs (14.3% vs 9.4%; P = 0.109), but in multivariate analysis only male sex, older age, and higher SBT scores were significantly related to mortality during hospitalization. At 3‐month follow‐up, only male sex, older age, and higher SBT scores were associated with mortality.

Conclusion

We found that the prescription of antipsychotic drugs during hospitalization was not associated with in‐hospital or follow‐up mortality. Short‐term antipsychotic prescriptions (for acutely ill patients) may have a different effect than long‐term, repeated prescriptions.
Investigation of a correlation between taxane‐based chemotherapy and the ultrasonic time‐of‐flight of human fingernails
Authors: Vacarescu R. A. , Slak B. , Maeva A. , Hamm C. , Lewoc N. , Daabous A. T. , Strumban E. , Maev R. G.
Published: June 2017

Background

Medical practitioners have long associated the physical appearance of human fingernails with certain underlying health conditions due to their direct connection to the vascular system. The objective of this study was to demonstrate how human fingernails can potentially be used as a biomarker to determine the severity of a patient's reaction to chemotherapy.

Methods

Quantitative investigation of fingernails in patients undergoing taxane‐based chemotherapy was conducted using a high‐frequency 50 MHz ultrasound device in B‐mode in the form of a pilot study. Time‐of‐Flight (TOF) ultrasonic signal measurements were recorded longitudinally across fingernails over three time intervals; (before treatment, in the middle of treatment, and on the last day of treatment); a neuropathy assessment and photographs were also taken for comparison.

Results

A total of 17 patients were examined in this study with ages ranging from 35‐69 years old with both weekly and biweekly chemotherapy regimens. Onycholysis and fingernail discoloration were observed in 8 of the 17 patients. White transverse lines and white lunula were observed on 4 of the 17 patients. Quantitative assessment revealed a TOF median decrease in fingernails during the first half of chemotherapy treatment; conversely, TOF median was found to have increased during the second half. Median TOF measurements at the end of treatment were found to return to approximately that of the baseline value.

Conclusion

This was a novel application of ultrasound in fingernails as chemotherapy biomarkers and further studies should be considered to verify and expand on the results obtained in this study.
A volatile discourse – reviewing aspects of ammonia emissions, models and atmospheric concentrations in The Netherlands
Authors: Hanekamp J. C. , Briggs W. M. , Crok M.
Published: June 2017

In the Netherlands, there is a vigorous debate on ammonia emissions, atmospheric concentrations and deposition between stakeholders and research institutions. In this article, we scrutinise some aspects of the ammonia discourse. In particular, we want to improve the understanding of the methodology for handling experimentally determined ammonia emissions. We show that uncertainty in published results is substantial. This uncertainty is under‐ or even unreported, and as a result, data in national emission inventories are overconfident by a wide margin. Next, we demonstrate that the statistical handling of data on atmospheric ammonia concentrations to produce national yearly atmospheric averages is oversimplified and consequently atmospheric concentrations are substantially overestimated. Finally, we show that the much‐discussed ‘ammonia gap’ – either the discrepancy between calculated and measured atmospheric ammonia concentrations or the difference observed between estimated NH3 emission levels and those indicated by atmospheric measurements – is an expression of the widespread overconfidence placed in atmospheric modelling.
Genome‐wide analysis of specific alterations in transcript structure and accumulation caused by nutrient deficiencies in Arabidopsis thaliana
Authors: Nishida Sho , Kakei Yusuke , Shimada Yukihisa , Fujiwara Toru
Published: June 2017

The alteration of transcript structure contributes to transcriptome plasticity. In this study, we analyzed the genome‐wide response of exon combination patterns to deficiencies in 12 different nutrients in Arabidopsis thaliana roots. RNA sequencing analysis and bioinformatics using a simulation survey revealed more than 600 genes showing varying exon combinations. The overlap between genes showing differential expression (DE) and genes showing differential exon combination (DC) was notably low. Additionally, gene ontology analysis showed that gene functions were not shared between the DE and DC genes, suggesting that the genes showing DC had different roles than those showing DE. Most of the DC genes were nutrient specific. For example, two homologs of the MYB transcription factor genes MYB48 and MYB59 showed differential alternative splicing only in response to low levels of potassium. Alternative splicing of those MYB genes modulated DNA‐binding motifs, and MYB59 is reportedly involved in the inhibition of root elongation. Therefore, the increased abundance of MYB isoforms with an intact DNA‐binding motif under low potassium may be involved in the active inhibition of root elongation. Overall, we provide global and comprehensive data for DC genes affected by nutritional deficiencies, which contribute to elucidating an unknown mechanism involved in adaptation to nutrient deficiency.
Development and testing of a stepwise thaw and dilute protocol for cryopreserved umbilical cord blood units
Authors: Pasha Roya , Elmoazzen Heidi , Pineault Nicolas
Published: June 2017

BACKGROUND

It is clinically important to maintain high viability and potency of umbilical cord blood units (CBUs) for transplantation during thawing. In the absence of a standard thawing protocol, this study was designed to develop one based on the consensus practice of transplant centers and address the shortage of dextran 40 thawing solution.

STUDY DESIGN AND METHODS

Frozen CBU aliquots were thawed using dextran 40 thawing solution while manipulating temperature and volume of diluent and mode of dilution. The effects of these on CD45+ and CD34+ cell viability were measured through annexin V and SYTOX green staining. The developed protocol was then used to compare dextran 40 and PLASMA‐LYTE A thawing solutions and finally tested on whole CBUs.

RESULTS

Step‐by‐step investigations resulted in the development of a protocol that thaws and dilutes CBUs with room temperature diluent to five times the original volume using two sequential dilutions separated by equilibration times. PLASMA‐LYTE A diluent provided superior viability of CD45+ and CD34+ cells than dextran 40 and recovered more colony‐forming units. However, both diluents were equally effective in maintaining stability of the thawed CBU for 4 hours. Moreover, the stem cell–enriched CD34+CD38– subpopulations appeared more resistant to cryoinjuries than their CD34+CD38+ counterpart.

CONCLUSION

The developed thawing protocol recovers viable CD45+ and CD34+ cells above the standard thresholds and maintains CBU potency. PLASMA‐LYTE A for thawing solution proved to be an efficient alternative to dextran 40. Finally, greater dilution should be avoided to maintain the viability of CD45+ cells and maximize graft cell dose.
Optimal control of the treatment frequency in a stochastic model of tuberculosis
Authors: Yves Sébastien Emvudu Wono , Danhree Bongor , Rodoumta Koïna
Published: June 2017

This paper presents a stochastic model of the Tuberculosis (TB) infection with treatment in a population composed of four individuals compartments: susceptible individuals, latent infected individuals, active infected individuals and recovered individuals after the therapy. The mathematical model of TB infection includes in addition to the deterministic term, a stochastic term that translates the random noise. The random nature of this model is due to the fact that the contraction of the Mycobacterium Tuberculosis, the vector agent of the TB infection and his transmission within the population are done in a random manner according to the variable efficiency of control of the immune system of the individuals. While supposing that only the active infected individuals transmit the infection, their survey in order to observe the rules of hygiene, to adopt a positive behavior with respect to the susceptible individuals (who must also take some precautions) to follow the treatment up to finish, constitute measures of adequate control. A preliminary survey of the model is made before approaching the crucial left of the topic. The main objective of this paper is to control the frequency of treatment in a stochastic model of the TB infection while minimizing the cost of the measures. We formulate an optimal control problem that consists in minimizing the relative cost to the dynamics of the model in order to reduce the prevalence and the mortality due to this infection. The optimal control problem is solved by applying the Projection Stochastic Gradient Method in order to find the optimal numerical solution. Finally, we provide some numerical simulations of the controlled model.
Electron Mobility across Grain Boundaries in Graphene Synthesized using Chemical Vapor Deposition Process
Authors: Long Fei , Kyoung Choi Chang
Published: June 2017

Chemical vapor deposition (CVD) is currently the only method for large-scale synthesis of graphene. However, the CVD process introduces grain boundaries (GBs) when individual grains coalesce with various mismatch angles. These GBs contain atomic dislocations and defects, which are believed to alter graphene's mechanical, electrical, and thermal properties. Specifically, the GBs can act as “potential barriers” when charges move from one grain to neighboring grains. This barrier effect will not only change the electrical conductivity but also the thermal conductivity of graphene. Besides high-resolution, 3-dimensional topography images, Atomic force microscopy (AFM) can also obtain the electrical properties at the nanoscale. In this report, the potential barrier effect of graphene GBs is studied with AFM. During the experiment, the probe is brought into contact with the graphene while positively (or negatively) biased. This process injects net charges into the graphene. The electrostatic potential across the GBs can be measured by AFM as an indication of the potential barrier effect. GBs with lower potential difference correspond to lower potential barrier, and vice versa. The dependency of the barrier effect on the mismatch angles was also measured. Considering the 6 folds’ symmetry of graphene atomic lattice, the mismatch angle is in the range of 0° ∼ 30°, with 30° the maximum mismatch angle. Our results can be well fitted with a sinusoidal function with π/3 period, which supports our hypothesis that higher mismatch angle contains higher density of dislocations and defects that increase the potential barrier of GBs.
Flow Boiling Heat Transfer of Subcooled Water on Sintered Microporous Surfaces
Authors: Kim Yeonghwan , Kim Junsub , M. You Seung , Lee Jungho , Sohn Jeong Lak , Lee Jungho
Published: June 2017

Electronic devices such as battery packs in electric vehicles and LED lights require advanced control in temperature uniformity for their optimum performance and prolonged lifetime. Flow boiling heat transfer of subcooled water (∆Tsub = 20K) in a 300 mm long minichannel with the cross section of 20×10 mm2 was investigated to improve the temperature uniformity over the entire minichannel. The minichannel was uniformity heated from the bottom copper surface. A 10 mm thick Pyrex glass was used for the top plate of the channel to visualize two-phase flow during the experiment. Microporous coating was fabricated by sintering copper particles on the top surface of the copper block. The average particle size was 50 μm, the average coating thickness was 300 μm, and the porosity was 41%, respectively. At the heat flux of 100 kW/m2, more bubbles are shown on the microporous surface compared with plain surface, resulting in better boiling heat transfer performance. These bubbles were large and stationary as liquid is evaporated and condensed to transport the heat as if heat pumps. As heat flux increases, bubble nucleation becomes more intensive, however, the larger stationary bubbles observed at 100 kW/m2 started to decrease. Most of the generated bubbles flowed through the downstream and they shrank quickly upon departure from the wall due to the 20K subcooling. High speed video showed some streaks of these small bubbles, and more streaks were observed as the heat flux increased. As shown in the left graph above, at 50 kW/m2 in subcooled flow boiling, both plain and microporous surfaces show similar local wall temperature because both are placed in the single-phase regime. In contrast, the difference of wall superheat between plain and porous surface is relatively large at higher heat flux of 500 kW/m2. Sintered microporous surface showed smaller increase in wall superheat compared with plain surface at higher wall superheat. [This study was supported by National Research Council of Science and Technology (NST) grant, Korea (Grant No. KIMM-NK203B)].
Mechanics of a Graphene Flake Driven by the Stiffness Jump on a Graphene Substrate
Authors: Gao Hong , Zhang Hongwei , Guo Zhengrong , Chang Tienchong , Chen Li-Qun
Published: June 2017

Intrinsic driving mechanism is of particular significance to nanoscale mass delivery and device design. Stiffness gradient-driven directional motion, i.e., nanodurotaxis, provides an intrinsic driving mechanism, but an in-depth understanding of the driving force is still required. Based on molecular dynamics (MD) simulations, here we investigate the motion behavior of a graphene flake on a graphene substrate with a stiffness jump. The effects of the temperature and the stiffness configuration on the driving force are discussed in detail. We show that the driving force is almost totally contributed by the unbalanced edge force and increases with the temperature and the stiffness difference but decreases with the stiffness level. We demonstrate in particular that the shuttle behavior of the flake between two stiffness jumps on the substrate can be controlled by the working temperature and stiffness configuration of the system, and the shuttle frequency can be well predicted by an analytical model. These findings may have general implications for the design of nanodevices driven by stiffness jumps.
Mixed Finite Elements for Flexoelectric Solids
Authors: Deng Feng , Deng Qian , Yu Wenshan , Shen Shengping
Published: June 2017

Flexoelectricity (FE) refers to the two-way coupling between strain gradients and the electric field in dielectric materials, and is universal compared to piezoelectricity, which is restricted to dielectrics with noncentralsymmetric crystalline structure. Involving strain gradients makes the phenomenon of flexoelectricity size dependent and more important for nanoscale applications. However, strain gradients involve higher order spatial derivate of displacements and bring difficulties to the solution of flexoelectric problems. This dilemma impedes the application of such universal phenomenon in multiple fields, such as sensors, actuators, and nanogenerators. In this study, we develop a mixed finite element method (FEM) for the study of problems with both strain gradient elasticity (SGE) and flexoelectricity being taken into account. To use C0 continuous elements in mixed FEM, the kinematic relationship between displacement field and its gradient is enforced by Lagrangian multipliers. Besides, four types of 2D mixed finite elements are developed to study the flexoelectric effect. Verification as well as validation of the present mixed FEM is performed through comparing numerical results with analytical solutions for an infinite tube problem. Finally, mixed FEM is used to simulate the electromechanical behavior of a 2D block subjected to concentrated force or voltage. This study proves that the present mixed FEM is an effective tool to explore the electromechanical behaviors of materials with the consideration of flexoelectricity.
Numerical and Experimental Studies on a Syngas-Fired Ultra Low NOx Combustor
Authors: Krishna S. , Ravikrishna R. V.
Published: June 2017

Simulations and exhaust measurements of temperature and pollutants in a syngas-fired model trapped vortex combustor for stationary power generation applications are reported. Numerical simulations employing Reynolds-averaged Navier–Stokes (RANS) and large eddy simulations (LES) with presumed probability distribution function (PPDF) model were also carried out. Mixture fraction profiles in the trapped vortex combustor (TVC) cavity for nonreacting conditions show that LES simulations are able to capture the mean mixing field better than the RANS-based approach. This is attributed to the prediction of the jet decay rate and is reflected on the mean velocity magnitude fields, which reinforce this observation at different sections in the cavity. Both RANS and LES simulations show close agreement with the experimentally measured OH concentration; however, the RANS approach does not perform satisfactorily in capturing the trend of velocity magnitude. LES simulations satisfactorily capture the trend observed in exhaust measurements which is primarily attributed to the flame stabilization mechanism. In the exhaust measurements, mixing enhancement struts were employed, and their effect was evaluated. The exhaust temperature pattern factor was found to be poor for baseline cases, but improved with the introduction of struts. NO emissions were steadily below 3 ppm across various flow conditions, whereas CO emissions tended to increase with increasing momentum flux ratios (MFRs) and mainstream fuel addition. Combustion efficiencies ∼96% were observed for all conditions. The performance characteristics were found to be favorable at higher MFRs with low pattern factors and high combustion efficiencies.
L1 Adaptive Control for Aircraft Air Management System Pressure-Regulating Bleed Valve
Authors: Cooper John , Cao Chengyu , Tang Jiong
Published: June 2017

This paper presents an L1 adaptive controller for pressure control using an engine bleed valve in an aircraft air management system (AMS). The air management system is composed of two pressure-regulating bleed valves, a temperature control valve, a flow control valve, and a heat exchanger/precooler. Valve hysteresis due to backlash and dry friction is included in the system model. The nonlinearities involved in the system cause oscillations under linear controllers, which decrease component life. This paper is the unique in the consideration of these uncertainties for control design. This paper presents simulation results using the adaptive controller and compares them to those using a proportional–integral (PI) controller.
Wind Turbine Blade Damage Detection Using Supervised Machine Learning Algorithms
Authors: Regan Taylor , Beale Christopher , Inalpolat Murat
Published: June 2017

Wind turbine blades undergo high operational loads, experience variable environmental conditions, and are susceptible to failure due to defects, fatigue, and weather-induced damage. These large-scale composite structures are fundamentally enclosed acoustic cavities and currently have limited, if any, structural health monitoring (SHM) in place. A novel acoustics-based structural sensing and health monitoring technique is developed, requiring efficient algorithms for operational damage detection of cavity structures. This paper describes the selection of a set of statistical features for acoustics-based damage detection of enclosed cavities, such as wind turbine blades, as well as a systematic approach used in the identification of competent machine learning algorithms. Logistic regression (LR) and support vector machine (SVM) methods are identified and used with optimal feature selection for decision-making via binary classification algorithms. A laboratory-scale wind turbine with hollow composite blades was built for damage detection studies. This test rig allows for testing of stationary or rotating blades, of which time and frequency domain information can be collected to establish baseline characteristics. The test rig can then be used to observe any deviations from the baseline characteristics. An external microphone attached to the tower will be utilized to monitor blade health while blades are internally ensonified by wireless speakers. An initial test campaign with healthy and damaged blade specimens is carried out to arrive at several conclusions on the detectability and feature extraction capabilities required for damage detection.
Reduced-Order Modeling of Bladed Disks With Friction Ring Dampers
Authors: Baek Seunghun , Epureanu Bogdan
Published: June 2017

An efficient methodology to predict the nonlinear response of bladed disks with a dry friction ring damper is proposed. Designing frictional interfaces for bladed-disk systems is an important approach to dissipate vibration energy. One emerging technology uses ring dampers, which are ringlike substructures constrained to move inside a groove at the root of the blades. Such rings are in contact with the bladed disk due to centrifugal forces, and they create nonlinear dissipation by relative motion between the ring and the disk. The analysis of the dynamic response of nonlinear structures is commonly done by numerical integration of the equations of motion, which is computationally inefficient, especially for steady-state responses. To address this issue, reduced-order models (ROMs) are developed to capture the nonlinear behavior due to contact friction. The approach is based on expressing the nonlinear forces as equivalent nonlinear damping and stiffness parameters. The method requires only sector-level calculations and allows precalculation of the response-dependent equivalent terms. These factors contribute to the increase of the computational speed of the iterative solution methods. A model of a bladed disk and damper is used to demonstrate the method. Macro- and micro-slip are used in the friction model to account for realistic behavior of dry friction damping. For validation, responses due to steady-state traveling wave excitations are examined. Results computed by ROMs are compared with results from transient dynamic analysis (TDA) in ansys with the full-order model. It is found that the steady-state responses predicted from the ROMs and the results from ansys are in good agreement, and that the ROMs reduce computation time significantly.
Surface engineering of poly(methylmethacrylate): Effects on fluorescence immunoassay
Authors: Akers Peter W. , Hoai Le Nam Cao , Nelson Andrew R. J. , McKenna Milena , O'Mahony Christy , McGillivray Duncan J. , Gubala Vladimir , Williams David E.
Published: June 2017

The authors present surface engineering modifications through chemistry of poly(methylmethacrylate) (PMMA) that have dramatic effects on the result of surface-bound fluorescence immunoassays, both for specific and nonspecific signals. The authors deduce the most important effect to be clustering of antibodies on the surface leading to significant self-quenching. Secondary effects are attributable to the formation of sparse multilayers of antibody. The authors compare PMMA as an antibody support surface with ultraviolet-ozone oxidized PMMA and also to substrates that were, after the oxidation, surface modified by a four-unit poly(ethyleneglycol) carboxylic acid (PEG4), a branched tricarboxylic acid, and a series of carboxylic acid-terminated dendrimers, from generation 1.5 to 5.5. Fluorescence immunoassay and neutron reflectometry were used to compare the apparent antibody surface loading, antigen binding and nonspecific binding on these various surfaces using anti-human IgG as a model antibody, chemically coupled to the surface by amide formation. Simple physical adsorption of the antibody on PMMA resulted in a thick antibody multilayer with small antigen binding capacity. On the carboxylated surfaces, with chemical coupling, a simple monolayer was formed. The authors deduce that antibody clustering was driven by conformational inflexibility and high carboxylate density. The PEG4-modified surface was the most conformationally flexible. The dendrimer-modified interfaces showed a collapse and densification. In fluorescence immunoassay, the optimal combination of high specific and low nonspecific fluorescence signal was found for the G3.5 dendrimer.
Evaluation of uncertainty for regularized deconvolution: A case study in hydrophone measurements
Authors: Eichstädt S. , Wilkens V.
Published: June 2017

An estimation of the measurand in dynamic metrology usually requires a deconvolution based on a dynamic calibration of the measuring system. Since deconvolution is, mathematically speaking, an ill-posed inverse problem, some kind of regularization is required to render the problem stable and obtain usable results. Many approaches to regularized deconvolution exist in the literature, but the corresponding evaluation of measurement uncertainties is, in general, an unsolved issue. In particular, the uncertainty contribution of the regularization itself is a topic of great importance, because it has a significant impact on the estimation result. Here, a versatile approach is proposed to express prior knowledge about the measurand based on a flexible, low-dimensional modeling of an upper bound on the magnitude spectrum of the measurand. This upper bound allows the derivation of an uncertainty associated with the regularization method in line with the guidelines in metrology. As a case study for the proposed method, hydrophone measurements in medical ultrasound with an acoustic working frequency of up to 7.5 MHz are considered, but the approach is applicable for all kinds of estimation methods in dynamic metrology, where regularization is required and which can be expressed as a multiplication in the frequency domain.
Detection of an undersea acoustic communications network by an energy detector
Authors: Shockley Richard C. , Gendron Paul J. , Stevenson J. Mark
Published: June 2017

A theory is presented for the upper bound on the mean time τ to the detection of an undersea acoustic communications network by an energy detector whose initial position and heading are uniformly distributed random variables. The network is an infinite square grid of omnidirectional transmit-receive nodes on a flat bottom. Each node transmits to one nearest neighbor at a bit-rate R equal to Shannon's capacity, maximizing τ. The network sets a signaling bandwidth W and node-spacing D. The detector sets a false-alarm rate, integration time, height above the bottom, and speed. For W = 5 kHz and D = 1 km, τ is computed as a function of R in 200 -m water with propagation varying from spherical to cylindrical spreading, volume absorption of 2 dB per km (corresponding approximately to 15 kHz), and illustrative values for other parameters.
Peptide Inhibitors Targeting the Neisseria gonorrhoeae Pivotal Anaerobic Respiration Factor AniA
Authors: Sikora Aleksandra E. , Mills Robert H. , Weber Jacob V. , Hamza Adel , Passow Bryan W. , Romaine Andrew , Williamson Zachary A. , Reed Robert W. , Zielke Ryszard A. , Korotkov Konstantin V.
Published: June 2017

Neisseria gonorrhoeae
causes the sexually transmitted infection gonorrhea, which is highly prevalent worldwide and has a major impact on reproductive and neonatal health. The superbug status of
N. gonorrhoeae
necessitates the development of drugs with different mechanisms of action. Here, we focused on targeting the nitrite reductase AniA, which is a pivotal component of
N. gonorrhoeae
anaerobic respiration and biofilm formation. Our studies showed that gonococci expressing AniA containing the altered catalytic residues D137A and H280A failed to grow under anaerobic conditions, demonstrating that the nitrite reductase function is essential. To facilitate the pharmacological targeting of AniA, new crystal structures of AniA were refined to 1.90-Å and 2.35-Å resolutions, and a phage display approach with libraries expressing randomized linear dodecameric peptides or heptameric peptides flanked by a pair of cysteine residues was utilized. Biopanning experiments led to the identification of 29 unique peptides, with 1 of them, C7-3, being identified multiple times. Evaluation of their ability to interact with AniA using enzyme-linked immunosorbent assay and computational docking studies revealed that C7-3 was the most promising inhibitor, binding near the type 2 copper site of the enzyme, which is responsible for interaction with nitrite. Subsequent enzymatic assays and biolayer interferometry with a synthetic C7-3 and its derivatives, C7-3m1 and C7-3m2, demonstrated potent inhibition of AniA. Finally, the MIC
50
value of C7-3 and C7-3m2 against anaerobically grown
N. gonorrhoeae
was 0.6 mM. We present the first peptide inhibitors of AniA, an enzyme that should be further exploited for antigonococcal drug development.
Role of AxyZ Transcriptional Regulator in Overproduction of AxyXY-OprZ Multidrug Efflux System in Achromobacter Species Mutants Selected by Tobramycin
Authors: Bador Julien , Neuwirth Catherine , Grangier Nadège , Muniz Marie , Germé Leslie , Bonnet Jérémy , Pillay Vignesh-Guru , Llanes Catherine , de Curraize Claire , Amoureux Lucie
Published: June 2017

AxyXY-OprZ is an RND-type efflux system that confers innate aminoglycoside resistance to
Achromobacter
spp. We investigated here a putative TetR family transcriptional regulator encoded by the
axyZ
gene located upstream of
axyXY-oprZ
. An in-frame
axyZ
gene deletion assay led to increased MICs of antibiotic substrates of the efflux system, including aminoglycosides, cefepime, fluoroquinolones, tetracyclines, and erythromycin, indicating that the product of
axyZ
negatively regulates expression of
axyXY-oprZ
. Moreover, we identified an amino acid substitution at position 29 of AxyZ (V29G) in a clinical
Achromobacter
strain that occurred during the course of chronic respiratory tract colonization in a cystic fibrosis (CF) patient. This substitution, also detected in three other strains exposed
in vitro
to tobramycin, led to an increase in the
axyY
transcription level (5- to 17-fold) together with an increase in antibiotic resistance level. This overproduction of AxyXY-OprZ is the first description of antibiotic resistance acquisition due to modification of a chromosomally encoded mechanism in
Achromobacter
and might have an impact on the management of infected CF patients. Indeed, tobramycin is widely used for aerosol therapy within this population, and we have demonstrated that it easily selects mutants with increased MICs of not only aminoglycosides but also fluoroquinolones, cefepime, and tetracyclines.
Multimechanistic Monoclonal Antibodies (MAbs) Targeting Staphylococcus aureus Alpha-Toxin and Clumping Factor A: Activity and Efficacy Comparisons of a MAb Combination and an Engineered Bispecific Antibody Approach
Authors: Tkaczyk C. , Kasturirangan S. , Minola A. , Jones-Nelson O. , Gunter V. , Shi Y. Y. , Rosenthal K. , Aleti V. , Semenova E. , Warrener P. , Tabor D. , Stover C. K. , Corti D. , Rainey G. , Sellman B. R.
Published: June 2017

Secreted alpha-toxin and surface-localized clumping factor A (ClfA) are key virulence determinants in
Staphylococcus aureus
bloodstream infections. We previously demonstrated that prophylaxis with a multimechanistic monoclonal antibody (MAb) combination against alpha-toxin (MEDI4893*) and ClfA (11H10) provided greater strain coverage and improved efficacy in an
S. aureus
lethal bacteremia model. Subsequently, 11H10 was found to exhibit reduced affinity and impaired inhibition of fibrinogen binding to ClfA002 expressed by members of a predominant hospital-associated methicillin-resistant
S. aureus
(MRSA) clone, ST5. Consequently, we identified another anti-ClfA MAb (SAR114) from human tonsillar B cells with >100-fold increased affinity for three prominent ClfA variants, including ClfA002, and potent inhibition of bacterial agglutination by 112 diverse clinical isolates. We next constructed bispecific Abs (BiSAbs) comprised of 11H10 or SAR114 as IgG scaffolds and grafted anti-alpha-toxin (MEDI4893*) single-chain variable fragment to the amino or carboxy terminus of the anti-ClfA heavy chains. Although the BiSAbs exhibited
in vitro
potencies similar to those of the parental MAbs, only 11H10-BiSAb, but not SAR114-BiSAb, showed protective activity in murine infection models comparable to the respective MAb combination.
In vivo
activity with SAR114-BiSAb was observed in infection models with
S. aureus
lacking ClfA. Our data suggest that high-affinity binding to ClfA sequesters the SAR114-BiSAb to the bacterial surface, thereby reducing both alpha-toxin neutralization and protection
in vivo
. These results indicate that a MAb combination targeting ClfA and alpha-toxin is more promising for future development than the corresponding BiSAb.
Linezolid Dose That Maximizes Sterilizing Effect While Minimizing Toxicity and Resistance Emergence for Tuberculosis
Authors: Srivastava Shashikant , Magombedze Gesham , Koeuth Thearith , Sherman Carleton , Pasipanodya Jotam G. , Raj Prithvi , Wakeland Edward , Deshpande Devyani , Gumbo Tawanda
Published: June 2017

Linezolid has an excellent sterilizing effect in tuberculosis patients but high adverse event rates. The dose that would maximize efficacy and minimize toxicity is unknown. We performed linezolid dose-effect and dose-scheduling studies in the hollow fiber system model of tuberculosis (HFS-TB) for sterilizing effect. HFS-TB units were treated with several doses to mimic human-like linezolid intrapulmonary pharmacokinetics and repetitively sampled for drug concentration, total bacterial burden, linezolid-resistant subpopulations, and RNA sequencing over 2 months. Linezolid-resistant isolates underwent whole-genome sequencing. The expression of genes encoding efflux pumps in the first 1 to 2 weeks revealed the same exposure-response patterns as the linezolid-resistant subpopulation. Linezolid-resistant isolates from the 2nd month of therapy revealed mutations in several efflux pump/transporter genes and a LuxR-family transcriptional regulator. Linezolid sterilizing effect was linked to the ratio of unbound 0- to 24-h area under the concentration-time curve (AUC
0–24
) to MIC. Optimal microbial kill was achieved at an AUC
0–24
/MIC ratio of 119. The optimal sterilizing effect dose for clinical use was identified using Monte Carlo simulations. Clinical doses of 300 and 600 mg/day (or double the dose every other day) achieved this target in 87% and >99% of 10,000 patients, respectively. The susceptibility breakpoint identified was 2 mg/liter. The simulations identified that a 300-mg/day dose did not achieve AUC
0–24
s associated with linezolid toxicity, while 600 mg/day achieved those AUC
0–24
s in <20% of subjects. The linezolid dose of 300 mg/day performed well and should be compared to 600 mg/day or 1,200 mg every other day in clinical trials.