bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethnopharmacology, phytochemistry, and biotechnological advances of family Apocynaceae: A review
Authors: Bhadane Bhushan S. , Patil Mohini P. , Maheshwari Vijay L. , Patil Ravindra H.
Published: March 2018

The family Apocynaceae is one of the largest and important families in angiosperm. Several members of this family have medicinal properties and have been in the treatment of various ailments. Most of them are consumed as food by tribal people whereas a few plants are used as source of poison. Members of family Apocynaceae are rich in alkaloids, terpenoids, steroids, flavonoids, glycosides, simple phenols, lactones, and hydrocarbons. Other compounds such as sterols, lignans, sugars, lignans, and lactones have been isolated and systematically studied. Few studies have reported antioxidant, anti‐inflammatory, antimicrobial, and cytotoxic activities of crude extracts as well as single compound(s) isolated from various members of the family Apocynaceae. Holarrhena antidysenterica, Rauvolfia serpentina, Carissa carandas, and Tabernaemontana divaricata are the extensively studied plants in this family. The present review provides a detailed outlook on ethnopharmacology, phytochemistry, and biological activities of selected members of this family. Moreover, it also covers the biotechnological advances used for large‐scale production of bioactive compounds of therapeutic interest along with plant tissue culture‐based approaches for conservation of this medicinally valuable family.
Epilobium spp: Pharmacology and Phytochemistry
Authors: Vitalone Annabella , Allkanjari Olta
Published: March 2018

The Epilobium species and their extracts are very popular in folk medicine, for a wide range of applications. The purpose of this review is the analysis of the pharmacological properties of Epilobium spp, considering whether their effects (e.g., anti‐inflammatory, antioxidant, antitumor, antimicrobial, analgesic, and antiandrogenic) could rationally justify the use of Epilobium as a treatment of numerous diseases. Even if numerous preclinical studies have been reported, randomized controlled clinical trials (for the evaluation of safety and efficacy), and eventually cost‐effectiveness studies (to estimate the long‐term cumulative costs), are still needed to confirm the usefulness of these medicinal plants in human diseases.
Modelling the moistening of the free troposphere during the northwestward progression of Indian monsoon onset
Authors: Menon A. , Turner A. G. , Martin G. M. , MacLachlan C.
Published: March 2018

Understanding and prediction of Indian monsoon onset is of paramount importance for agricultural planning, which affects food production and the gross domestic product of the country. A recent observational study suggests that the progression of the Indian monsoon onset in a northwestward direction, which is perpendicular to the mean flow, is reinforced by the moistening of the free troposphere by pre‐monsoon showers and wetting of the land surface. As the onset progresses, the mid‐tropospheric dry layer is thought to be constantly moistened from below by detrainment from shallow cumulus and congestus clouds from the southeast. The dry layer becomes much shallower towards southeast India, making the profile closer to moist adiabatic, providing favourable conditions for deep cumulus convection. Increased moistening of the free troposphere thereby pushes the northern limit of moist convection northwestwards. Here, we examine the representation of this process in hindcast simulations from the fully coupled atmosphere–ocean seasonal forecast system of the UK Met Office, GloSea5. The model effectively captures the mid‐level dry‐air intrusion from the northwest that suppresses convection over the northwestern parts of India. We also show that detrainment from shallow convection, measured by moisture tendencies around the freezing level, acts to saturate the free troposphere ahead of the monsoon onset, eroding the dry layer from the southeast. This work suggests that initialized coupled models are capable of simulating dynamic and thermodynamic processes inherent in monsoon progression during the onset.
An overview of the TROPICS NASA Earth Venture Mission
Authors: Blackwell W. J. , Braun S. , Bennartz R. , Velden C. , DeMaria M. , Atlas R. , Dunion J. , Marks F. , Rogers R. , Annane B. , Leslie R. V.
Published: March 2018

The Time‐Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA as part of the Earth Venture‐Instrument (EVI‐3) program. The overarching goal for TROPICS is to provide nearly all‐weather observations of 3D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high‐value science investigations of tropical cyclones. TROPICS will provide rapid‐refresh microwave measurements (median refresh rate better than 60 min for the baseline mission) which can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm life cycle. TROPICS comprises six CubeSats in three low‐Earth orbital planes. Each CubeSat will host a high‐performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapour profiles using three channels near the 183 GHz water vapour absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher‐resolution water vapour channels), and a single channel near 205 GHz which is more sensitive to precipitation‐sized ice particles. This observing system offers an unprecedented combination of horizontal and temporal resolution to measure environmental and inner‐core conditions for tropical cyclones on a nearly global scale and is a major leap forward in the temporal resolution of several key parameters needed for assimilation into advanced data assimilation systems capable of utilizing rapid‐update radiance or retrieval data. Launch readiness is currently projected for late 2019.
Attenuation relations for monsoonal rain at the X band from disdrometric measurements: Dependency on temperature, raindrop size distribution and drop shape models
Authors: Narayana Rao T. , Amarjyothi K. , Rao S.V.B.
Published: March 2018

Four years of disdrometric measurements made at Gadanki (13.5°N, 79.18°E), which receives rainfall during both southwest and northeast monsoons, have been used to (a) derive optimal attenuation relations for monsoonal rainfall at the X band, (b) study the impact of seasonal variation in raindrop size distribution (DSD) on attenuation relations and (c) analyze the dependency of these relations on the controlling parameters/models, such as temperature (T) and drop shape model. The results clearly show that the coefficients of these relations vary significantly with DSD (season and rain type), T and drop shape model, and are quite different for monsoonal rain than for those obtained elsewhere. The traditional relations that involve a specific attenuation (AH)‐reflectivity factor at horizontal polarization (ZH) and AH‐rain rate depend heavily on DSD and to some extent on T, while the relations involving a specific differential phase (KDP) and differential attenuation (ADP) show strong dependency on the drop shape model and DSD, but depend weakly on T. A detailed investigation has been carried out to decipher reasons for the observed intriguing seasonal variation in KDP‐based relations and their temperature dependency. The resonance scattering effects that are thought to be negligible at the X band in earlier studies appear to play a dominant role here and are primarily responsible for the observed features.
An improved moist‐convective rotating shallow‐water model and its application to instabilities of hurricane‐like vortices
Authors: Rostami Masoud , Zeitlin Vladimir
Published: March 2018

We show how the two‐layer moist‐convective rotating shallow‐water model (mcRSW), which proved to be a simple and robust tool for studying effects of moist convection for large‐scale atmospheric motions, can be improved. The improvement is achieved by including, in addition to the water vapour, precipitable water, and the effects of vaporization, entrainment, and precipitation, rendering the model cloud‐resolving. It is applied, as an illustration, to model the development of instabilities of tropical cyclone‐like vortices.
CRPS chart: Simultaneously monitoring location and scale under data‐rich environment
Authors: Shi Liangxing , Gong Ling , Lin Dennis K.J.
Published: March 2018

The detection performance of a conventional control chart is usually degraded by a large sample size as in Wang and Tsung. This paper proposes a new control chart under data‐rich environment. The proposed chart is based on the continuous ranked probability score and aims to simultaneously monitor the location and the scale parameters of any continuous process. We simulate different monitoring schemes with various shift patterns to examine the chart performance. Both in‐control and out‐of‐control performances are studied through simulation studies in terms of the mean, the standard deviation, the median, and some percentiles of the average run length distribution. Simulation results show that the proposed chart keeps a high sensitivity to shifts in location and/or scale without any distributional assumptions, and the outperformance improves, as the sample size becomes larger. Examples are given for illustration.
Reliability assessment of complex electromechanical systems: A network perspective
Authors: Lin Shuai , Wang Yanhui , Jia Limin , Zhang Hengrun
Published: March 2018

The network theory is widely applied to improve the reliability of a complex electromechanical system. In this application, system reliability assessment with network theory has been paid a great deal of attention. Because of instrument malfunctions, staff omissions, imperfect inspection strategies, and complex structures, field failure data are often subject to interval censoring, making the holistic reliability assessment becomes a difficult task. Most traditional methods assume reliability of critical components or partial reliability as system reliability, which may cause a large bias in system reliability estimation. This paper proposes a novel method to evaluate and predict the system reliability of a complex electromechanical system subject to the insufficient fault data problem from a network perspective. First, the system modeling based on network theory is developed to describe the topology of a holistic system. Second, interval‐valued intuitionistic hesitant fuzzy number is proposed in order to solve insufficient data for single component. Then, a new measure—comprehensive reliability—that can reflect the reliability of nodes in combination with functional properties and topological properties, which are formulated by failure data and network model, respectively, is constructed for system reliability assessment. Subsequently, an improved system reliability model based on percolation theory is given in terms of comprehensive reliability of nodes. Finally, to verify the effectiveness of the proposed method, a simulation and a real case study for traction system are implemented.
Assessing the impact of requirements review on quality outcomes
Authors: White Timothy E. , Iammartino Ronald , Fossaceca John M.
Published: March 2018

Studies demonstrate that differences in how product development organizations and product realization organizations interpret requirements can lead to poor‐quality outcomes. Other research shows that in comparison to communicating requirements inside an organization, communicating requirements in buyer‐supplier relationships can be more difficult and has been identified as a source of rework, poor quality, and increased costs. The Raytheon Company identified misaligned requirements interpretation between the company and its suppliers as a source of program performance inefficiency and therefore instituted a collaborative requirements review process between the company and its critical suppliers. This study examines the impact of these requirements reviews on quality outcomes and demonstrates that these reviews result in positive quality outcomes. In addition, correlation analysis shows a relationship between conducting the requirements reviews and a reduction in failure modes that are characterized by high detection and remediation effort. Considered broadly, our methodology can be applied to other program performance improvement efforts to test their impact on quality outcomes and to reveal related failure modes.
Halogen in materials design: Fluoroammonium lead triiodide (FNH3PbI3) perovskite as a newly discovered dynamical bandgap semiconductor in 3D
Authors: Varadwaj Arpita , Varadwaj Pradeep R. , Yamashita Koichi
Published: March 2018

Methylammonium lead triiodide (CH3NH3PbI3) has been recognized as one of the record‐breaking materials for photovoltaics since it can potentially convert light energy into electricity @ 23%. However, it has been suffering from serious stability and environmental issues for which it is not yet put on market. To this end, experimental and theoretical studies are underway to discover versatile halide‐based perovskite compounds. In this article, we report the polymorphic geometries, stabilities, band structures, density of states spectra, and carrier effective asses of a newly identified perovskite semiconductor called fluoroammonium lead triiodide (FNH3PbI3), obtained using compositional engineering combined with periodic density functional theory electronic structure calculations. We show that this compound is stable both in the orthorhombic and pseudocubic phases. We also show that the bandgap for this material oscillates between 1.62 eV (direct) and 1.79 (indirect) for the two polymorphs examined in the pseudocubic phase, with the former and latter values corresponding to the [111] and [110] orientations of the inorganic cationinside the perovskite cage, respectively. Contrariwise, it is direct at Γ‐point for the polymorph examined in the orthorhombic phase. The spin orbit coupling is displayed to have profound effect on the nature and magnitude of the bandgap for this material. This, together with the very small effective masses calculated for the charge carriers comparable with those of CH3NH3PbI3, allows us to propose that FNH3PbI3could be a possible candidate for photovoltaics, as well as for other optoelectronic applications.
Mapping the tandem mass spectrometric characteristics of citrulline‐containing peptides
Authors: Steckel Arnold , Uray Katalin , Turiák Lilla , Gömöry Ágnes , Drahos László , Hudecz Ferenc , Schlosser Gitta
Published: March 2018

Rationale

Protein citrullination (deimination) is a post‐translational modification of proteins converting arginine(s) into citrulline(s). “Overcitrullination” could be associated with severe pathological conditions. Mass spectrometric analysis of modified proteins is hindered by several problems. A comprehensive study of the fragmentation of deiminated peptides is not yet available. In this paper we have made an attempt to describe the characteristics of these processes, based on the studies of epitope model oligopeptides derived from clinically relevant proteins.

Methods

Solutions of purified model peptides containing either one or two citrulline residues as well as their native variants were injected directly into the electrospray source of a high accuracy and resolution quadrupole‐time‐of‐flight instrument and were analysed by tandem mass spectrometry using low‐energy collision‐induced dissociation.

Results

Loss of isocyanic acid from citrulline residues is a preferred fragmentation route for deiminated peptides, which yields ornithine residues in the sequence. However, simultaneous detection of both the isocyanic acid loss and sequence fragments is often compromised. A preferential cleavage site was observed between citrulline and any other following amino acids yielding intensive complementary b‐ and y‐type ions. Also, citrulline positioned at the C‐termini displays a preferential cleavage N‐terminal to this residue yielding characteristic y1 ions. These phenomena are described here for the first time and are referred to as the “citrulline effect”.

Conclusions

We found that the citrulline effect is very pronounced and could be used as a complementary tool for the confirmation of modification sites in addition to losses of isocyanic acids from the protonated molecules or from fragment ions. Low collision energy applied to peptide ions having partially mobile protons reveals the site of modification by generating specific and intensive fragments of the sequence. On the other hand, fragmenting precursor ions with mobile protons usually allows full sequence coverage, although citrulline‐specific fragments may exhibit lower intensities compared to other fragments.
Matrix‐assisted laser desorption/ionization imaging mass spectrometry of intraperitoneally injected danegaptide (ZP1609) for treatment of stroke‐reperfusion injury in mice
Authors: Wang Jasmine S.H. , Freitas‐Andrade Moises , Bechberger John F. , Naus Christian C. , Yeung Ken K.‐C. , Whitehead Shawn N.
Published: March 2018

Rationale

This work focuses on direct matrix‐assisted laser desorption/ionization imaging mass spectrometry (MALDI‐IMS) detection of intraperitoneally (IP)‐injected dipeptide ZP1609 in mouse brain tissue. Direct analysis of drug detection in intact tissue sections provides distribution information that can impact drug development. MALDI‐IMS capabilities of uncovering drug transport across the blood–brain barrier are demonstrated.

Methods

Successful peptide detection using MALDI‐IMS was achieved using a MALDI TOF/TOF system. Upon optimization of sample preparation procedures for dipeptide ZP1609, an additional tissue acidification procedure was found to greatly enhance signal detection. The imaging data acquired was able to determine successful transport of ZP1609 across the blood–brain barrier. Data obtained from MALDI‐IMS can help shape our understanding of biological functions, disease progression, and effects of drug delivery.

Results

Direct detection of ZP1609 throughout the brain tissue sections was observed from MALDI‐MS images. However, in cases where there was induction of stroke, a peak of lower signal intensity was also detected in the target m/z region. Although distinct differences in signal intensity can be seen between control and experimental groups, fragments and adducts of ZP1609 were investigated using MALDI‐IMS to verify detection of the target analyte.

Conclusions

Overall, the data reveals successful penetration of ZP1609 across the blood–brain barrier. The benefits of tissue acidification in the enhancement of detection sensitivity for low‐abundance peptides were demonstrated. MALDI‐IMS has been shown to be a useful technique in the direct detection of drugs within intact brain tissue sections.
On‐line capillary electrophoresis/laser‐induced fluorescence/mass spectrometry analysis of glycans labeled with Teal™ fluorescent dye using an electrokinetic sheath liquid pump‐based nanospray ion source
Authors: Khan Shaheer , Liu Jenkuei , Szabo Zoltan , Kunnummal Baburaj , Han Xiaorui , Ouyang Yilan , Linhardt Robert J. , Xia Qiangwei
Published: March 2018

Rationale

N‐linked glycan analysis of recombinant therapeutic proteins, such as monoclonal antibodies, Fc‐fusion proteins, and antibody‐drug conjugates, provides valuable information regarding protein therapeutics glycosylation profile. Both qualitative identification and quantitative analysis of N‐linked glycans on recombinant therapeutic proteins are critical analytical tasks in the biopharma industry during the development of a biotherapeutic.

Methods

Currently, such analyses are mainly carried out using capillary electrophoresis/laser‐induced fluorescence (CE/LIF), liquid chromatography/fluorescence (LC/FLR), and liquid chromatography/fluorescence/mass spectrometry (LC/FLR/MS) technologies. N‐linked glycans are first released from glycoproteins by enzymatic digestion, then labeled with fluorescence dyes for subsequent CE or LC separation, and LIF or MS detection. Here we present an on‐line CE/LIF/MS N‐glycan analysis workflow that incorporates the fluorescent Teal™ dye and an electrokinetic pump‐based nanospray sheath liquid capillary electrophoresis/mass spectrometry (CE/MS) ion source.

Results

Electrophoresis running buffer systems using ammonium acetate and ammonium hydroxide were developed for the negative ion mode CE/MS analysis of fluorescence‐labeled N‐linked glycans. Results show that on‐line CE/LIF/MS analysis can be readily achieved using this versatile CE/MS ion source on common CE/MS instrument platforms.

Conclusions

This on‐line CE/LIF/MS method using Teal™ fluorescent dye and electrokinetic pump‐based nanospray sheath liquid CE/MS coupling technology holds promise for on‐line quantitation and identification of N‐linked glycans on recombinant therapeutic proteins.
Three‐dimensional Kendrick mass plots as a tool for graphical lipid identification
Authors: Korf Ansgar , Vosse Christian , Schmid Robin , Helmer Patrick O. , Jeck Viola , Hayen Heiko
Published: March 2018

Rationale

The rising field of lipidomics strongly relies on the identification of lipids in complex matrices. Recent technical advances regarding liquid chromatography (LC) and high‐resolution mass spectrometry (HRMS) enable the mapping of the lipidome of an organism with short data acquisition times. However, interpretation and evaluation of resulting multidimensional datasets are challenging and this is still the bottleneck regarding overall analysis times.

Methods

A novel adaption of Kendrick mass plot analysis is presented for a rapid and accurate analysis of lipids in complex matrices. Separation of lipids by their respective head group was achieved via hydrophilic interaction liquid chromatography (HILIC) coupled to HRMS. The resulting LC/HRMS datasets are processed to a list of chromatographically separated features by applying an optimized MZmine 2 workflow. All features are plotted in a three‐dimensional Kendrick mass plot, which allows a fast identification of present lipid classes, based on equidistant features with fitting retention times and the same Kendrick mass defect. Suspected lipid classes are used for exact mass database matching to annotate features. A second three‐dimensional Kendrick mass plot of annotated features of a single lipid class helps to reveal potential database mismatches, resulting in a curated list of identified lipid species.

Results

The use of the novel adaption of the Kendrick mass plot has accelerated the identification of the relevant lipid species in the green alga Chlamydomonas reinhardtii. A total of 106 species were identified within the lipid classes: phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol.

Conclusions

This work shows how the addition of chromatographic information, i.e. the retention time, to a classical two‐dimensional Kendrick mass plot enables rapid and accurate analysis of LC/HRMS datasets, exemplified on a green alga (C. reinhardtii) sample. Three‐dimensional Kendrick mass plots have improved lipid class identification and fast spotting of falsely annotated lipid species.
Influence of room temperature on magnesium isotope measurements by multi‐collector inductively coupled plasma mass spectrometry
Authors: Zhang Xing‐Chao , Zhang An‐Yu , Zhang Zhao‐Feng , Huang Fang , Yu Hui‐Min
Published: March 2018

Rationale

We observed that the accuracy and precision of magnesium (Mg) isotope analyses could be affected if the room temperature oscillated during measurements. To achieve high‐quality Mg isotopic data, it is critical to evaluate how the unstable room temperature affects Mg isotope measurements by multi‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS).

Methods

We measured the Mg isotopes for the reference material DSM‐3 using MC‐ICP‐MS under oscillating room temperatures in spring. For a comparison, we also measured the Mg isotopes under stable room temperatures, which were achieved by the installation of an improved temperature control system in the laboratory.

Results

The δ26Mg values measured under oscillating room temperatures have a larger deviation (δ26Mg from −0.09 to 0.08‰, with average δ26Mg = 0.00 ± 0.08‰) than those measured under a stable room temperature (δ26Mg from −0.03 to 0.03‰, with average δ26Mg = 0.00 ± 0.02‰) using the same MC‐ICP‐MS system.

Conclusions

The room temperature variation can influence the stability of MC‐ICP‐MS. Therefore, it is critical to keep the room temperature stable to acquire high‐precision and accurate isotopic data when using MC‐ICP‐MS, especially when using the sample‐standard bracketing (SSB) correction method.
Rapid oligonucleotide drug impurity determination by direct spectral comparison of ion‐pair reversed‐phase high‐performance liquid chromatography electrospray ionization mass spectrometry data
Authors: Roussis Stilianos G. , Koch Charlie , Capaldi Daniel , Rentel Claus
Published: March 2018

Rationale

Quantitative ion‐pair (IP) high‐performance liquid chromatography/mass spectrometry (HPLC/MS) methods are employed to determine the complex impurity profiles of oligonucleotide therapeutics. While impurities that co‐elute with the main product are routinely monitored, the large number of early and late eluting impurities makes their individual measurements tedious and time‐consuming. An improved method is needed for routine analyses.

Methods

A Combined Ranking (CR) index is developed to provide a composite value for both qualitative and quantitative impurity changes. Positive and Negative Impurity Change (PIC/NIC) indices are developed to determine the degree and direction of change. Optimized experimental conditions are determined for the characterization of trace levels of impurities. Replicate analysis, blank subtraction, and signal processing approaches are used to enhance the signal‐to noise (S/N). Dot‐product and Euclidean distance equations monitor spectral changes.

Results

Spiking experiments with individual and complex impurity mixtures show the method can distinguish among samples differing in impurity content by 0.2% wt. The method has been applied to monitor changes in impurity profiles among different batches of the same oligonucleotide and changes in the same batch over time (stability analysis). The method permits rapid determination of changes in the types and amounts (increases and decreases) of impurities present.

Conclusions

A novel approach for the rapid determination of changes in the impurity profile of oligonucleotide therapeutics has been developed. The straightforward data treatment and the speed and simplicity of the approach make the method easy to implement and use. Possible quality control applications include drug substance and drug product stability studies, and the assessment of batch‐to‐batch variability.
Position‐specific 13C/12C analysis of amino acid carboxyl groups – automated flow‐injection analysis based on reaction with ninhydrin
Authors: Fry Brian , Carter James F. , Yamada Keita , Yoshida Naohiro , Juchelka Dieter
Published: March 2018

Rationale

The fundamental level of stable isotopic knowledge lies at specific atomic positions within molecules but existing methods of analysis require lengthy off‐line preparation to reveal this information. An automated position‐specific isotope analysis (PSIA) method is presented to determine the stable carbon isotopic compositions of the carboxyl groups of amino acids (δ13CCARBOXYL values). This automation makes PSIA measurements easier and routine.

Methods

An existing high‐performance liquid chromatography (HPLC) gas handling interface/stable isotope ratio mass spectrometry system was modified by the addition of a post‐column derivatisation unit between the HPLC system and the interface. The post‐column reaction was optimised to yield CO2 from the carboxyl groups of amino acids by reaction with ninhydrin.

Results

The methodology described produced δ13CCARBOXYL values with typical standard deviations below ±0.1 ‰ and consistent differences (Δ13CCARBOXYL values) between amino acids over a 1‐year period. First estimates are presented for the δ13CCARBOXYL values of a number of internationally available amino acid reference materials.

Conclusions

The PSIA methodology described provides a further dimension to the stable isotopic characterisation of amino acids at a more detailed level than the bulk or averaged whole‐molecule level. When combined with on‐line chromatographic separation or off‐line fraction collection of protein hydrolysates the technique will offer an automated and routine way to study position‐specific carboxyl carbon isotope information for amino acids, enabling more refined isotopic studies of carbon uptake and metabolism.
Three‐dimensional augmented reality surgical navigation with hybrid optical and electromagnetic tracking for distal intramedullary nail interlocking
Authors: Ma Longfei , Zhao Zhe , Zhang Boyu , Jiang Weipeng , Fu Ligong , Zhang Xinran , Liao Hongen
Published: March 2018

Background

Intramedullary nail (IMN) fixation improves functional outcomes for the diaphyseal fractures of long bones. However, locking the distal holes of the IMN is challenging. Although several navigation methods have been proposed, an intuitive, radiation‐free and accurate navigation method that does not suffer from problems of hand–eye coordination has not yet been described.

Methods

This paper proposes an augmented reality (AR) surgical navigation method with hybrid optical and electromagnetic (EM) tracking for distal IMN interlocking. Model experiments are designed to evaluate the AR‐guided distal interlocking method.

Results

AR‐guided drilling procedures were performed on 5 tibia models and a leg phantom. The accuracy (hit or miss) was evaluated using fluoroscopy. The experimental results demonstrated that all 18 drills successfully hit the distal holes at a rate of 100%.

Conclusions

Our results indicate that the AR‐guided distal interlocking method is feasible and has many potential applications in clinic after further evaluation.
Distributed consensus of second‐order multiagent systems with nonconvex input constraints
Authors: Mo Lipo , Lin Peng
Published: March 2018

This paper addresses the input constrained consensus of second‐order multiagent systems with nonconvex constraints. A new update law is proposed to make the position states of all agents converge to a common point and the velocities converge to zero, while the input of each agent stays in a certain constraint set. The closed‐loop system is first converted to an equivalent system by taking a novel coordinate transformation. Then, it is proved that the input constrained consensus can be achieved if the graphs jointly have directed spanning trees by using the Metzler matrix theory. Finally, simulations are provided to demonstrate the effectiveness of the proposed algorithm.
Practical time‐varying formation tracking for high‐order nonlinear multiagent systems with multiple leaders based on the distributed disturbance observer
Authors: Yu Jianglong , Dong Xiwang , Liang Zixuan , Li Qingdong , Ren Zhang
Published: March 2018

Practical time‐varying formation tracking analysis and design problems for high‐order nonlinear multiagent systems with directed interaction topologies are investigated by using the distributed disturbance observer, where the time‐varying formation tracking error can be controlled within an arbitrarily small bound. Different from the previous work, there exists a predefined time‐varying formation formed by the states of the followers and the formation tracks the convex combination of the states of the leaders with unknown control inputs. Besides, the leaders can be multiple, and the dynamics of each follower has heterogeneous nonlinearity and disturbance. First, a distributed disturbance observer‐based practical time‐varying formation tracking protocol is constructed using neighboring relative information, where only a part of the followers, which are named as well‐informed ones, are required to obtain the information of the multiple leaders. The proposed protocol can process the heterogeneous nonlinearity, the disturbance of each follower, and the unknown control inputs of the leaders simultaneously. Then, an algorithm with 2 steps is presented to design the practical time‐varying formation tracking protocol by solving an algebraic Riccati equation and an algebraic equation, where the time‐varying formation tracking feasibility condition is introduced. Moreover, the stability of the closed‐loop multiagent system under the proposed protocol is proved by using the properties of the Laplacian matrix and the Lyapunov stability theory. Finally, a numerical simulation example is provided to illustrate the effectiveness of the obtained theoretical results.
Time‐varying feedback for stabilization in prescribed finite time
Authors: Song Yongduan , Wang Yujuan , Krstic Miroslav
Published: March 2018

This paper provides a time‐varying feedback alternative to control of finite‐time systems, which is referred to as “prescribed‐time control,” exhibiting several superior features: (i) such time‐varying gain–based prescribed‐time control is built upon regular state feedback rather than fractional‐power state feedback, thus resulting in smooth (Cm) control action everywhere during the entire operation of the system; (ii) the prescribed‐time control is characterized with uniformly prespecifiable convergence time that can be preassigned as needed within the physically allowable range, making it literally different from not only the traditional finite‐time control (where the finite settling time is determined by a system initial condition and a number of design parameters) but also the fixed‐time control (where the settling time is subject to certain constraints and thus can only be specified within the corresponding range); and (iii) the prescribed‐time control relies only on regular Lyapunov differential inequality instead of fractional Lyapunov differential inequality for stability analysis and thus avoids the difficulty in controller design and stability analysis encountered in the traditional finite‐time control for high‐order systems.
Adaptive decentralized fault‐tolerant tracking control for large‐scale nonlinear systems with input quantization
Authors: Wang Cai‐Cheng , Yang Guang‐Hong
Published: March 2018

In this paper, an adaptive decentralized tracking control scheme is designed for large‐scale nonlinear systems with input quantization, actuator faults, and external disturbance. The nonlinearities, time‐varying actuator faults, and disturbance are assumed to exist unknown upper and lower bounds. Then, an adaptive decentralized fault‐tolerant tracking control method is designed without using backstepping technique and neural networks. In the proposed control scheme, adaptive mechanisms are used to compensate the effects of unknown nonlinearities, input quantization, actuator faults, and disturbance. The designed adaptive control strategy can guarantee that all the signals of each subsystem are bounded and the tracking errors of all subsystems converge asymptotically to zero. Finally, simulation results are provided to illustrate the effectiveness of the designed approach.
Robust adaptive quantized DSC of uncertain pure‐feedback nonlinear systems with time‐varying output and state constraints
Authors: Xia Xiaonan , Zhang Tianping
Published: March 2018

In this paper, the problem of neural adaptive dynamic surface quantized control is studied the first time for a class of pure‐feedback nonlinear systems in the presence of state and output constraint and unmodeled dynamics. The considered system is under the control of a hysteretic quantized input signal. Two types of one‐to‐one nonlinear mapping are adopted to transform the pure‐feedback system with different output and state constraints into an equivalent unconstrained pure‐feedback system. By designing a novel control law based on modified dynamic surface control technique, many assumptions of the quantized system in early literary works are removed. The unmodeled dynamics is estimated by a dynamic signal and approximated based on neural networks. The stability analysis indicates that all the signals in the closed‐loop system are semiglobally uniformly ultimately bounded, and the output and all the states remain in the prescribed time‐varying or constant constraints. Two numerical examples with a coarse quantizer show that the proposed approach is effective for the considered system.
Adaptive asymptotic stabilization of switched parametric strict‐feedback systems with switched control
Authors: Zhai Ding , An Liwei , Zhang Qing‐Ling
Published: March 2018

This paper is concerned with the problem of adaptive stabilization for a class of switched linear‐parametric nonlinear systems under arbitrary switching. The traditional adaptive backstepping control is successfully extended to switched systems from nonswitched ones where the asymptotic regulation of system state is not destroyed due to rapid or abrupt changes of switching parameters. A new switched adaptive controller is designed by exploiting a common high‐order Lyapunov function with a σ‐modification mechanism, which can reflect sufficiently the changes of plant by designing different adaptive laws and control laws for different subsystems. An explicit formula for constructing a continuous and piecewise
virtual control function is given to remove the restriction where some
bound functions have to be constructed blindly by designers in the existing results, which may be somewhat too strict to be applied. A numerical example is provided to validate the proposed approach.
Homogeneous control law design for output synchronization of networked Lur'e‐type systems with disturbances
Authors: Li Ranran , Yang Guang‐Hong
Published: March 2018

In this paper, the homogeneous distributed control law is proposed such that the outputs of the networked Lur'e systems with disturbances are synchronized. A novel adaptive distributed state‐based disturbance compensator technique is utilized such that the disturbances can be offset asymptotically. The design of the distributed compensator is constructive in that some particular functions of the states of the Lur'e systems are included. The functions always exist for the considered Lur'e‐type system. Moreover, a theorem of networked Lur'e systems subject to disturbances is first presented to show the boundedness of the states of the closed‐loop system. Then, the synchronization is shown by the incremental passivity theory and graph theory. Finally, the effectiveness of the current method is illustrated by the networked Van der Pol oscillators with disturbances.
A Simultaneous Analysis of Relations Between L1 and L2 Skills in Reading and Writing
Authors: Pae Tae‐Il
Published: March 2018

This study examines relations between the first language (L1) and second language (L2) in reading and writing for 211 upper middle school Korean students learning English as a foreign language. Results using path analysis suggest that L1 ability is a significant independent predictor of L2 ability in both reading and writing, providing evidence of interdependent relations between L1 and L2 operations in receptive and productive skills. Results also indicate that L1 reading predicted L2 writing, but L1 writing did not predict L2 reading. L2 proficiency was also shown to be important. L2 proficiency made a greater contribution to L2 reading and writing operations than L1 ability did. Also, the relation between L1 and L2 writing skills but not reading skills was significantly moderated by L2 proficiency. The author discusses results in the context of existing theories about L1–L2 relations and highlights important implications for pedagogy and future research.
Addressing the estimation of standard errors in fixed effects meta‐analysis
Authors: Domínguez Islas Clara , Rice Kenneth M.
Published: March 2018

Standard methods for fixed effects meta‐analysis assume that standard errors for study‐specific estimates are known, not estimated. While the impact of this simplifying assumption has been shown in a few special cases, its general impact is not well understood, nor are general‐purpose tools available for inference under more realistic assumptions. In this paper, we aim to elucidate the impact of using estimated standard errors in fixed effects meta‐analysis, showing why it does not go away in large samples and quantifying how badly miscalibrated standard inference will be if it is ignored. We also show the important role of a particular measure of heterogeneity in this miscalibration. These developments lead to confidence intervals for fixed effects meta‐analysis with improved performance for both location and scale parameters.
Subgroup analysis with semiparametric models toward precision medicine
Authors: Yuan Ao , Chen Xiaofei , Zhou Yizhao , Tan Ming T.
Published: March 2018

In analyzing clinical trials, one important objective is to classify the patients into treatment‐favorable and nonfavorable subgroups. Existing parametric methods are not robust, and the commonly used classification rules ignore the fact that the implications of treatment‐favorable and nonfavorable subgroups can be different. To address these issues, we propose a semiparametric model, incorporating both our knowledge and uncertainty about the true model. The Wald statistics is used to test the existence of subgroups, while the Neyman‐Pearson rule to classify each subject. Asymptotic properties are derived, simulation studies are conducted to evaluate the performance of the method, and then method is used to analyze a real‐world trial data.
Outside CEOs and innovation
Authors: Cummings Trey , Knott Anne Marie
Published: March 2018

Research Summary: Innovation is the principle driver of firm and economic growth. Thus, one disturbing trend that may explain stagnant growth is a 65% decline in firms’ R&D productivity. We propose that the rise of outside Chief Executive Officers (CEOs) may be partially responsible for the decline because those CEOs are more likely to lack technological domain expertise necessary to manage R&D effectively. While this proposition was motivated by interviews with Chief Technology Officers (CTOs), we test it at large scale. We find that firm R&D productivity decays during the tenure of outside CEOs relative to that of inside CEOs. We further find this effect is more pronounced for firms with high R&D intensity and for firms employing outside CEOs with more remote experience, lending circumstantial support for the underlying assumption regarding lack of expertise. Note that this is not a call for boards to avoid outside CEOs, rather it is recommendation to consider the implications for innovation.

Managerial Summary: While outside CEOs offer advantages over internal candidates, we argue one unintended consequence is weaker innovation. This argument was prompted by two coincident trends: a 65% decline in companies’ R&D productivity and a doubling of outside Chief Executive Officers (CEOs). The argument was reinforced by interviews with Chief Technology Officers (CTOs), who recounted shifts in orientation from R&D as an investment to R&D as an expense that occurred shortly in response to a new CEO. We felt this shift was more likely with outside CEOs because they may lack technological domain expertise necessary to effectively manage R&D. Our results are consistent with the argument—company R&D productivity decreases under outside CEOs. Note, however, that we don’t advocate avoiding outside CEOs, rather we recommend R&D firms consider technological domain expertise during CEO hiring.
Quantitative Analysis of Multiple Proteins of Different Invasive Tumor Cell Lines at the Same Single‐Cell Level
Authors: Zhang Xiangchun , Liu Ru , Shu Qingming , Yuan Qing , Xing Gengmei , Gao Xueyun
Published: March 2018

Tumor cell invasion is pivotal to the development, metastasis, and prognosis of tumors. It is reported that the invasive ability of tumor cells is mainly dependent on the expression levels of membrane type‐1 matrix metalloproteinase (MT1‐MMP) and integrin αVβ3 proteins on cell membranes. To precisely distinguish between tumor cells with different invasive abilities, it is important to establish a highly sensitive and precise quantification method to differentiate the expression levels of MT1‐MMP and integrin αVβ3 in the same single tumor cell at the same time. Herein, two functional peptides to construct red‐emissive Au26 clusters and green‐emissive Ag12 clusters are reported. Moreover, the Au26 clusters and Ag12 clusters have the ability to specifically target MT1‐MMP and integrin αVβ3, respectively, in the same single cell at the same time. By utilizing the fluorescent properties and metallic compositions of metal clusters, the MT1‐MMP and integrin αVβ3 levels of the more invasive SiHa cells or the less invasive HeLa cells are simultaneously and quantitatively differentiated via laser ablation inductively coupled plasma mass spectrometry. This method of quantitatively detecting multiple invasive proteins on the same cell is of great value for accurately diagnosing aggressive tumors and monitoring the invasiveness of these tumors.
Electrochemical Biosensor Composed of Silver Ion‐Mediated dsDNA on Au‐Encapsulated Bi2Se3 Nanoparticles for the Detection of H2O2 Released from Breast Cancer Cells
Authors: Mohammadniaei Mohsen , Yoon Jinho , Lee Taek , Bharate Bapurao G. , Jo Jinhee , Lee Donghyun , Choi Jeong‐Woo
Published: March 2018

A newly developed electrochemical biosensor composed of a topological insulator (TI) and metallic DNA (mDNA) is fabricated. The bismuth selenide nanoparticle (Bi2Se3 NP) is synthesized and sandwiched between the gold electrode and another Au‐deposited thin layer (Bi2Se3@Au). Then, eight‐silver‐ion mediated double‐stranded DNA (mDNA) is immobilized onto the substrate (Bi2Se3@Au‐mDNA) for the further detection of hydrogen peroxide. The Bi2Se3 NP acts as the electrochemical‐signal booster, while unprecedentedly its encapsulation by the Au thin layer keeps the TI surface states protected, improves its electrochemical‐signal stability and provides an excellent platform for the subsequent covalent immobilization of the mDNA through Au–thiol interaction. Electrochemical results show that the fabricated biosensor represents much higher Ag+ redox current (≈10 times) than those electrodes prepared without Bi2Se3@Au. The characterization of the Bi2Se3@Au‐mDNA film is confirmed by atomic force microscopy, scanning tunneling microscopy, and cyclic voltammetry. The proposed biosensor shows a dynamic range of 00.10 × 10−6m to 27.30 × 10−6m, very low detection limit (10 × 10−9m), unique current response (1.6 s), sound H2O2 recovery in serum, and substantial capability to classify two breast cancer subtypes (MCF‐7 and MDA‐MB‐231) based on their difference in the H2O2 generation, offering potential applications in the biomedicine and pharmacology fields.